Towards payment.

15 files changed, 1131 insertions, 446 deletions

diff --git a/extension/background/db.js b/extension/background/db.js
index b52ee457a..f6d81d9ac 100644
--- a/extension/background/db.js
+++ b/extension/background/db.js
@@ -1,5 +1,34 @@
+"use strict";
+const DB_NAME = "taler";
+const DB_VERSION = 1;
 /**
- * Declarations and helpers for
- * things that are stored in the wallet's
- * database.
+ * Return a promise that resolves
+ * to the taler wallet db.
  */
+function openTalerDb() {
+    return new Promise((resolve, reject) => {
+        let req = indexedDB.open(DB_NAME, DB_VERSION);
+        req.onerror = (e) => {
+            reject(e);
+        };
+        req.onsuccess = (e) => {
+            resolve(req.result);
+        };
+        req.onupgradeneeded = (e) => {
+            let db = req.result;
+            console.log("DB: upgrade needed: oldVersion = " + e.oldVersion);
+            switch (e.oldVersion) {
+                case 0:
+                    let mints = db.createObjectStore("mints", { keyPath: "baseUrl" });
+                    mints.createIndex("pubKey", "keys.master_public_key");
+                    db.createObjectStore("reserves", { keyPath: "reserve_pub" });
+                    db.createObjectStore("denoms", { keyPath: "denomPub" });
+                    let coins = db.createObjectStore("coins", { keyPath: "coinPub" });
+                    coins.createIndex("mintBaseUrl", "mintBaseUrl");
+                    db.createObjectStore("transactions", { keyPath: "contractHash" });
+                    db.createObjectStore("precoins", { keyPath: "coinPub", autoIncrement: true });
+                    break;
+            }
+        };
+    });
+}
diff --git a/extension/background/db.ts b/extension/background/db.ts
new file mode 100644
index 000000000..12d944a83
--- /dev/null
+++ b/extension/background/db.ts
@@ -0,0 +1,89 @@
+"use strict";
+/**
+ * Declarations and helpers for
+ * things that are stored in the wallet's
+ * database.
+ */
+
+
+
+namespace Db {
+  export interface Mint {
+    baseUrl: string;
+    keys: Keys
+  }
+
+  export interface CoinWithDenom {
+    coin: Coin;
+    denom: Denomination;
+  }
+
+  export interface Keys {
+    denoms: { [key: string]: Denomination };
+  }
+
+  export interface Denomination {
+    value: AmountJson;
+    denom_pub: string;
+    fee_withdraw: AmountJson;
+    fee_deposit: AmountJson;
+  }
+
+  export interface PreCoin {
+    coinPub: string;
+    coinPriv: string;
+    reservePub: string;
+    denomPub: string;
+    blindingKey: string;
+    withdrawSig: string;
+    coinEv: string;
+    mintBaseUrl: string;
+    coinValue: AmountJson;
+  }
+  
+  export interface Coin {
+    coinPub: string;
+    coinPriv: string;
+    denomPub: string;
+    denomSig: string;
+    currentAmount: AmountJson;
+  }
+
+
+}
+
+
+const DB_NAME = "taler";
+const DB_VERSION = 1;
+
+/**
+ * Return a promise that resolves
+ * to the taler wallet db.
+ */
+function openTalerDb(): Promise<IDBDatabase> {
+  return new Promise((resolve, reject) => {
+    let req = indexedDB.open(DB_NAME, DB_VERSION);
+    req.onerror = (e) => {
+      reject(e);
+    };
+    req.onsuccess = (e) => {
+      resolve(req.result);
+    };
+    req.onupgradeneeded = (e) => {
+      let db = req.result;
+      console.log ("DB: upgrade needed: oldVersion = " + e.oldVersion);
+      switch (e.oldVersion) {
+        case 0: // DB does not exist yet
+          let mints = db.createObjectStore("mints", { keyPath: "baseUrl" });
+          mints.createIndex("pubKey", "keys.master_public_key");
+          db.createObjectStore("reserves", { keyPath: "reserve_pub"});
+          db.createObjectStore("denoms", { keyPath: "denomPub" });
+          let coins = db.createObjectStore("coins", { keyPath: "coinPub" });
+          coins.createIndex("mintBaseUrl", "mintBaseUrl");
+          db.createObjectStore("transactions", { keyPath: "contractHash" });
+          db.createObjectStore("precoins", { keyPath: "coinPub", autoIncrement: true });
+          break;
+      }
+    };
+  });
+}
diff --git a/extension/background/emscriptif.js b/extension/background/emscriptif.js
index 81580fbed..15eef7a3a 100644
--- a/extension/background/emscriptif.js
+++ b/extension/background/emscriptif.js
@@ -1,19 +1,19 @@
 /*
 
-  This file is part of TALER
-  Copyright (C) 2014, 2015 Christian Grothoff (and other contributing authors)
+ This file is part of TALER
+ Copyright (C) 2014, 2015 Christian Grothoff (and other contributing authors)
 
-  TALER is free software; you can redistribute it and/or modify it under the
-  terms of the GNU General Public License as published by the Free Software
-  Foundation; either version 3, or (at your option) any later version.
+ TALER is free software; you can redistribute it and/or modify it under the
+ terms of the GNU General Public License as published by the Free Software
+ Foundation; either version 3, or (at your option) any later version.
 
-  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
-  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
-  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
 
-  You should have received a copy of the GNU General Public License along with
-  TALER; see the file COPYING. If not, see <http://www.gnu.org/licenses/>
-*/
+ You should have received a copy of the GNU General Public License along with
+ TALER; see the file COPYING. If not, see <http://www.gnu.org/licenses/>
+ */
 "use strict";
 // Size of a native pointer.
 const PTR_SIZE = 4;
@@ -30,6 +30,7 @@ var emsc = {
     amount_add: getEmsc('TALER_amount_add', 'number', ['number', 'number', 'number']),
     amount_subtract: getEmsc('TALER_amount_subtract', 'number', ['number', 'number', 'number']),
     amount_normalize: getEmsc('TALER_amount_normalize', 'void', ['number']),
+    amount_get_zero: getEmsc('TALER_amount_get_zero', 'number', ['string', 'number']),
     amount_cmp: getEmsc('TALER_amount_cmp', 'number', ['number', 'number']),
     amount_hton: getEmsc('TALER_amount_hton', 'void', ['number', 'number']),
     amount_ntoh: getEmsc('TALER_amount_ntoh', 'void', ['number', 'number']),
@@ -62,6 +63,7 @@ var emscAlloc = {
 var SignaturePurpose;
 (function (SignaturePurpose) {
     SignaturePurpose[SignaturePurpose["RESERVE_WITHDRAW"] = 1200] = "RESERVE_WITHDRAW";
+    SignaturePurpose[SignaturePurpose["WALLET_COIN_DEPOSIT"] = 1201] = "WALLET_COIN_DEPOSIT";
 })(SignaturePurpose || (SignaturePurpose = {}));
 var RandomQuality;
 (function (RandomQuality) {
@@ -138,7 +140,7 @@ class SyncArena extends DefaultArena {
         super();
         let me = this;
         this.timer = new Worker('background/timerThread.js');
-        this.timer.onmessage = (e) => {
+        this.timer.onmessage = () => {
             this.destroy();
         };
         //this.timer.postMessage({interval: 50});
@@ -164,6 +166,14 @@ class Amount extends ArenaObject {
             emsc.free(this.nativePtr);
         }
     }
+    static getZero(currency, a) {
+        let am = new Amount(null, a);
+        let r = emsc.amount_get_zero(currency, am.getNative());
+        if (r != GNUNET_OK) {
+            throw Error("invalid currency");
+        }
+        return am;
+    }
     toNbo(a) {
         let x = new AmountNbo(a);
         x.alloc();
@@ -260,7 +270,9 @@ class PackedArenaObject extends ArenaObject {
     }
 }
 class AmountNbo extends PackedArenaObject {
-    size() { return 24; }
+    size() {
+        return 24;
+    }
 }
 class EddsaPrivateKey extends PackedArenaObject {
     static create(a) {
@@ -268,30 +280,60 @@ class EddsaPrivateKey extends PackedArenaObject {
         obj.nativePtr = emscAlloc.eddsa_key_create();
         return obj;
     }
-    size() { return 32; }
+    size() {
+        return 32;
+    }
     getPublicKey(a) {
         let obj = new EddsaPublicKey(a);
         obj.nativePtr = emscAlloc.eddsa_public_key_from_private(this.nativePtr);
         return obj;
     }
 }
-class EddsaPublicKey extends PackedArenaObject {
-    size() { return 32; }
+mixinStatic(EddsaPrivateKey, fromCrock);
+function fromCrock(s) {
+    let x = new this();
+    x.alloc();
+    x.loadCrock(s);
+    return x;
 }
-class RsaBlindingKey extends ArenaObject {
-    static create(len, a) {
-        let o = new RsaBlindingKey(a);
-        o.nativePtr = emscAlloc.rsa_blinding_key_create(len);
-        return o;
+function mixin(obj, method, name) {
+    if (!name) {
+        name = method.name;
     }
-    static fromCrock(s, a) {
+    if (!name) {
+        throw Error("Mixin needs a name.");
+    }
+    console.log("mixing in", name, "into", obj.name);
+    obj.prototype[method.name] = method;
+}
+function mixinStatic(obj, method, name) {
+    if (!name) {
+        name = method.name;
+    }
+    if (!name) {
+        throw Error("Mixin needs a name.");
+    }
+    console.log("mixing in", name, "into", obj.name);
+    obj[method.name] = method;
+}
+class EddsaPublicKey extends PackedArenaObject {
+    size() {
+        return 32;
+    }
+}
+mixinStatic(EddsaPublicKey, fromCrock);
+function makeFromCrock(decodeFn) {
+    function fromCrock(s, a) {
         let obj = new this(a);
         let buf = ByteArray.fromCrock(s);
-        obj.setNative(emscAlloc.rsa_blinding_key_decode(buf.getNative(), buf.size()));
+        obj.setNative(decodeFn(buf.getNative(), buf.size()));
         buf.destroy();
         return obj;
     }
-    toCrock() {
+    return fromCrock;
+}
+function makeToCrock(encodeFn) {
+    function toCrock() {
         let ptr = emscAlloc.malloc(PTR_SIZE);
         let size = emscAlloc.rsa_blinding_key_encode(this.nativePtr, ptr);
         let res = new ByteArray(size, Module.getValue(ptr, '*'));
@@ -300,12 +342,27 @@ class RsaBlindingKey extends ArenaObject {
         res.destroy();
         return s;
     }
+    return toCrock;
+}
+class RsaBlindingKey extends ArenaObject {
+    constructor(...args) {
+        super(...args);
+        this.toCrock = makeToCrock(emscAlloc.rsa_blinding_key_encode);
+    }
+    static create(len, a) {
+        let o = new RsaBlindingKey(a);
+        o.nativePtr = emscAlloc.rsa_blinding_key_create(len);
+        return o;
+    }
     destroy() {
         // TODO
     }
 }
+mixinStatic(RsaBlindingKey, makeFromCrock(emscAlloc.rsa_blinding_key_decode));
 class HashCode extends PackedArenaObject {
-    size() { return 64; }
+    size() {
+        return 64;
+    }
     random(qualStr) {
         let qual;
         switch (qualStr) {
@@ -328,6 +385,7 @@ class HashCode extends PackedArenaObject {
         emsc.hash_create_random(qual, this.nativePtr);
     }
 }
+mixinStatic(HashCode, fromCrock);
 class ByteArray extends PackedArenaObject {
     constructor(desiredSize, init, a) {
         super(a);
@@ -339,7 +397,9 @@ class ByteArray extends PackedArenaObject {
         }
         this.allocatedSize = desiredSize;
     }
-    size() { return this.allocatedSize; }
+    size() {
+        return this.allocatedSize;
+    }
     static fromString(s, a) {
         let hstr = emscAlloc.malloc(s.length + 1);
         Module.writeStringToMemory(s, hstr);
@@ -364,7 +424,9 @@ class EccSignaturePurpose extends PackedArenaObject {
         this.nativePtr = emscAlloc.purpose_create(purpose, payload.nativePtr, payload.size());
         this.payloadSize = payload.size();
     }
-    size() { return this.payloadSize + 8; }
+    size() {
+        return this.payloadSize + 8;
+    }
 }
 class SignatureStruct {
     constructor(x) {
@@ -393,8 +455,7 @@ class SignatureStruct {
             ptr += size;
         }
         let ba = new ByteArray(totalSize, buf, a);
-        let x = new EccSignaturePurpose(this.purpose(), ba);
-        return x;
+        return new EccSignaturePurpose(this.purpose(), ba);
     }
     set(name, value) {
         let typemap = {};
@@ -414,32 +475,68 @@ class WithdrawRequestPS extends SignatureStruct {
     constructor(w) {
         super(w);
     }
-    purpose() { return SignaturePurpose.RESERVE_WITHDRAW; }
+    purpose() {
+        return SignaturePurpose.RESERVE_WITHDRAW;
+    }
     fieldTypes() {
         return [
             ["reserve_pub", EddsaPublicKey],
             ["amount_with_fee", AmountNbo],
             ["withdraw_fee", AmountNbo],
             ["h_denomination_pub", HashCode],
-            ["h_coin_envelope", HashCode]];
+            ["h_coin_envelope", HashCode]
+        ];
     }
 }
-function encodeWith(obj, fn, arena) {
-    let ptr = emscAlloc.malloc(PTR_SIZE);
-    let len = fn(obj.getNative(), ptr);
-    let res = new ByteArray(len, null, arena);
-    res.setNative(Module.getValue(ptr, '*'));
-    emsc.free(ptr);
-    return res;
+class AbsoluteTimeNbo extends PackedArenaObject {
+    static fromTalerString(s) {
+        throw Error();
+    }
+    size() {
+        return 8;
+    }
 }
-class RsaPublicKey extends ArenaObject {
-    static fromCrock(s, a) {
-        let obj = new RsaPublicKey(a);
-        let buf = ByteArray.fromCrock(s);
-        obj.nativePtr = emscAlloc.rsa_public_key_decode(buf.nativePtr, buf.size());
-        buf.destroy();
-        return obj;
+class UInt64 extends PackedArenaObject {
+    static fromNumber(n) {
+        throw Error();
+    }
+    size() {
+        return 8;
+    }
+}
+class DepositRequestPS extends SignatureStruct {
+    constructor(w) {
+        super(w);
+    }
+    purpose() {
+        return SignaturePurpose.WALLET_COIN_DEPOSIT;
+    }
+    fieldTypes() {
+        return [
+            ["h_contract", HashCode],
+            ["h_wire", HashCode],
+            ["timestamp", AbsoluteTimeNbo],
+            ["refund_deadline", AbsoluteTimeNbo],
+            ["transaction_id", UInt64],
+            ["amount_with_fee", AmountNbo],
+            ["deposit_fee", AmountNbo],
+            ["merchant", EddsaPublicKey],
+            ["coin_pub", EddsaPublicKey],
+        ];
+    }
+}
+function makeEncode(encodeFn) {
+    function encode(arena) {
+        let ptr = emscAlloc.malloc(PTR_SIZE);
+        let len = encodeFn(this.getNative(), ptr);
+        let res = new ByteArray(len, null, arena);
+        res.setNative(Module.getValue(ptr, '*'));
+        emsc.free(ptr);
+        return res;
     }
+    return encode;
+}
+class RsaPublicKey extends ArenaObject {
     toCrock() {
         return this.encode().toCrock();
     }
@@ -447,38 +544,26 @@ class RsaPublicKey extends ArenaObject {
         emsc.rsa_public_key_free(this.nativePtr);
         this.nativePtr = 0;
     }
-    encode(arena) {
-        let ptr = emscAlloc.malloc(PTR_SIZE);
-        let len = emscAlloc.rsa_public_key_encode(this.nativePtr, ptr);
-        let res = new ByteArray(len, Module.getValue(ptr, '*'), arena);
-        emsc.free(ptr);
-        return res;
-    }
 }
+mixinStatic(RsaPublicKey, makeFromCrock(emscAlloc.rsa_public_key_decode));
+mixin(RsaPublicKey, makeEncode(emscAlloc.rsa_public_key_encode));
 class EddsaSignature extends PackedArenaObject {
-    size() { return 64; }
+    size() {
+        return 64;
+    }
 }
 class RsaSignature extends ArenaObject {
-    static fromCrock(s, a) {
-        let obj = new this(a);
-        let buf = ByteArray.fromCrock(s);
-        obj.setNative(emscAlloc.rsa_signature_decode(buf.getNative(), buf.size()));
-        buf.destroy();
-        return obj;
-    }
-    encode(arena) {
-        return encodeWith(this, emscAlloc.rsa_signature_encode);
-    }
     destroy() {
         emsc.rsa_signature_free(this.getNative());
         this.setNative(0);
     }
 }
+mixinStatic(RsaSignature, makeFromCrock(emscAlloc.rsa_signature_decode));
+mixin(RsaSignature, makeEncode(emscAlloc.rsa_signature_encode));
 function rsaBlind(hashCode, blindingKey, pkey, arena) {
     let ptr = emscAlloc.malloc(PTR_SIZE);
     let s = emscAlloc.rsa_blind(hashCode.nativePtr, blindingKey.nativePtr, pkey.nativePtr, ptr);
-    let res = new ByteArray(s, Module.getValue(ptr, '*'), arena);
-    return res;
+    return new ByteArray(s, Module.getValue(ptr, '*'), arena);
 }
 function eddsaSign(purpose, priv, a) {
     let sig = new EddsaSignature(a);
diff --git a/extension/background/emscriptif.ts b/extension/background/emscriptif.ts
index f21e60db4..ce6f351c0 100644
--- a/extension/background/emscriptif.ts
+++ b/extension/background/emscriptif.ts
@@ -1,23 +1,23 @@
 /*
 
-  This file is part of TALER
-  Copyright (C) 2014, 2015 Christian Grothoff (and other contributing authors)
+ This file is part of TALER
+ Copyright (C) 2014, 2015 Christian Grothoff (and other contributing authors)
 
-  TALER is free software; you can redistribute it and/or modify it under the
-  terms of the GNU General Public License as published by the Free Software
-  Foundation; either version 3, or (at your option) any later version.
+ TALER is free software; you can redistribute it and/or modify it under the
+ terms of the GNU General Public License as published by the Free Software
+ Foundation; either version 3, or (at your option) any later version.
 
-  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
-  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
-  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+ TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
 
-  You should have received a copy of the GNU General Public License along with
-  TALER; see the file COPYING. If not, see <http://www.gnu.org/licenses/>
-*/
+ You should have received a copy of the GNU General Public License along with
+ TALER; see the file COPYING. If not, see <http://www.gnu.org/licenses/>
+ */
 
 "use strict";
 
-declare var Module : any;
+declare var Module: any;
 
 
 // Size of a native pointer.
@@ -30,10 +30,18 @@ const GNUNET_SYSERR = -1;
 
 
 interface EmscFunGen {
-  (name: string, ret: string, args: string[]): ((...x: (number|string)[]) => any);
-  (name: string, ret: 'number', args: string[]): ((...x: (number|string)[]) => number);
-  (name: string, ret: 'void', args: string[]): ((...x: (number|string)[]) => void);
-  (name: string, ret: 'string', args: string[]): ((...x: (number|string)[]) => string);
+  (name: string,
+   ret: string,
+   args: string[]): ((...x: (number|string)[]) => any);
+  (name: string,
+   ret: 'number',
+   args: string[]): ((...x: (number|string)[]) => number);
+  (name: string,
+   ret: 'void',
+   args: string[]): ((...x: (number|string)[]) => void);
+  (name: string,
+   ret: 'string',
+   args: string[]): ((...x: (number|string)[]) => string);
 }
 
 let getEmsc: EmscFunGen = (...args) => Module.cwrap.apply(null, args);
@@ -58,15 +66,18 @@ var emsc = {
   amount_normalize: getEmsc('TALER_amount_normalize',
                             'void',
                             ['number']),
+  amount_get_zero: getEmsc('TALER_amount_get_zero',
+                           'number',
+                           ['string', 'number']),
   amount_cmp: getEmsc('TALER_amount_cmp',
                       'number',
                       ['number', 'number']),
   amount_hton: getEmsc('TALER_amount_hton',
-                      'void',
-                      ['number', 'number']),
+                       'void',
+                       ['number', 'number']),
   amount_ntoh: getEmsc('TALER_amount_ntoh',
-                      'void',
-                      ['number', 'number']),
+                       'void',
+                       ['number', 'number']),
   hash: getEmsc('GNUNET_CRYPTO_hash',
                 'void',
                 ['number', 'number', 'number']),
@@ -77,8 +88,8 @@ var emsc = {
                                'void',
                                ['number']),
   rsa_signature_free: getEmsc('GNUNET_CRYPTO_rsa_signature_free',
-                               'void',
-                               ['number']),
+                              'void',
+                              ['number']),
   string_to_data: getEmsc('GNUNET_STRINGS_string_to_data',
                           'number',
                           ['number', 'number', 'number', 'number']),
@@ -89,8 +100,8 @@ var emsc = {
                               'void',
                               ['number', 'number']),
   rsa_blinding_key_destroy: getEmsc('GNUNET_CRYPTO_rsa_blinding_key_free',
-                              'void',
-                              ['number']),
+                                    'void',
+                                    ['number']),
 };
 
 var emscAlloc = {
@@ -99,9 +110,10 @@ var emscAlloc = {
                       ['number', 'number', 'number', 'string']),
   eddsa_key_create: getEmsc('GNUNET_CRYPTO_eddsa_key_create',
                             'number', []),
-  eddsa_public_key_from_private: getEmsc('TALER_WRALL_eddsa_public_key_from_private',
-                                         'number',
-                                         ['number']),
+  eddsa_public_key_from_private: getEmsc(
+    'TALER_WRALL_eddsa_public_key_from_private',
+    'number',
+    ['number']),
   data_to_string_alloc: getEmsc('GNUNET_STRINGS_data_to_string_alloc',
                                 'number',
                                 ['number', 'number']),
@@ -112,35 +124,36 @@ var emscAlloc = {
                      'number',
                      ['number', 'number', 'number', 'number']),
   rsa_blinding_key_create: getEmsc('GNUNET_CRYPTO_rsa_blinding_key_create',
-                               'number',
-                               ['number']),
+                                   'number',
+                                   ['number']),
   rsa_blinding_key_encode: getEmsc('GNUNET_CRYPTO_rsa_blinding_key_encode',
-                               'number',
-                               ['number', 'number']),
+                                   'number',
+                                   ['number', 'number']),
   rsa_signature_encode: getEmsc('GNUNET_CRYPTO_rsa_signature_encode',
-                               'number',
-                               ['number', 'number']),
+                                'number',
+                                ['number', 'number']),
   rsa_blinding_key_decode: getEmsc('GNUNET_CRYPTO_rsa_blinding_key_decode',
-                               'number',
-                               ['number', 'number']),
+                                   'number',
+                                   ['number', 'number']),
   rsa_public_key_decode: getEmsc('GNUNET_CRYPTO_rsa_public_key_decode',
-                               'number',
-                               ['number', 'number']),
+                                 'number',
+                                 ['number', 'number']),
   rsa_signature_decode: getEmsc('GNUNET_CRYPTO_rsa_signature_decode',
-                               'number',
-                               ['number', 'number']),
+                                'number',
+                                ['number', 'number']),
   rsa_public_key_encode: getEmsc('GNUNET_CRYPTO_rsa_public_key_encode',
-                               'number',
-                               ['number', 'number']),
+                                 'number',
+                                 ['number', 'number']),
   rsa_unblind: getEmsc('GNUNET_CRYPTO_rsa_unblind',
-                               'number',
-                               ['number', 'number', 'number']),
+                       'number',
+                       ['number', 'number', 'number']),
   malloc: (size: number) => Module._malloc(size),
 };
 
 
 enum SignaturePurpose {
-  RESERVE_WITHDRAW = 1200
+  RESERVE_WITHDRAW = 1200,
+  WALLET_COIN_DEPOSIT = 1201,
 }
 
 enum RandomQuality {
@@ -153,6 +166,7 @@ enum RandomQuality {
 abstract class ArenaObject {
   private _nativePtr: number;
   arena: Arena;
+
   abstract destroy(): void;
 
   constructor(arena?: Arena) {
@@ -172,7 +186,7 @@ abstract class ArenaObject {
     // of native wrappers, but we never want to
     // pass 'undefined' to emscripten.
     if (this._nativePtr === undefined) {
-     throw Error("Native pointer not initialized");
+      throw Error("Native pointer not initialized");
     }
     return this._nativePtr;
   }
@@ -198,11 +212,11 @@ abstract class ArenaObject {
     this._nativePtr = n;
   }
 
-  set nativePtr (v) {
+  set nativePtr(v) {
     this.setNative(v);
   }
 
-  get nativePtr () {
+  get nativePtr() {
     return this.getNative();
   }
 
@@ -215,6 +229,7 @@ interface Arena {
 
 class DefaultArena implements Arena {
   heap: Array<ArenaObject>;
+
   constructor() {
     this.heap = [];
   }
@@ -238,31 +253,35 @@ class DefaultArena implements Arena {
  */
 class SyncArena extends DefaultArena {
   timer: Worker;
+
   constructor() {
     super();
     let me = this;
     this.timer = new Worker('background/timerThread.js');
-    this.timer.onmessage = (e) => {
+    this.timer.onmessage = () => {
       this.destroy();
     };
     //this.timer.postMessage({interval: 50});
   }
+
   destroy() {
     super.destroy();
   }
 }
 
 
-
 let arenaStack: Arena[] = [];
 arenaStack.push(new SyncArena());
 
 
 class Amount extends ArenaObject {
-  constructor(args?: any, arena?: Arena) {
+  constructor(args?: AmountJson, arena?: Arena) {
     super(arena);
     if (args) {
-      this.nativePtr = emscAlloc.get_amount(args.value, 0, args.fraction, args.currency);
+      this.nativePtr = emscAlloc.get_amount(args.value,
+                                            0,
+                                            args.fraction,
+                                            args.currency);
     } else {
       this.nativePtr = emscAlloc.get_amount(0, 0, 0, "");
     }
@@ -274,6 +293,17 @@ class Amount extends ArenaObject {
     }
   }
 
+
+  static getZero(currency: string, a?: Arena) {
+    let am = new Amount(null, a);
+    let r = emsc.amount_get_zero(currency, am.getNative());
+    if (r != GNUNET_OK) {
+      throw Error("invalid currency");
+    }
+    return am;
+  }
+
+
   toNbo(a?: Arena): AmountNbo {
     let x = new AmountNbo(a);
     x.alloc();
@@ -362,7 +392,10 @@ abstract class PackedArenaObject extends ArenaObject {
     // We need to get the javascript string
     // to the emscripten heap first.
     let buf = ByteArray.fromString(s);
-    let res = emsc.string_to_data(buf.nativePtr, s.length, this.nativePtr, this.size());
+    let res = emsc.string_to_data(buf.nativePtr,
+                                  s.length,
+                                  this.nativePtr,
+                                  this.size());
     buf.destroy();
     if (res < 1) {
       throw {error: "wrong encoding"};
@@ -390,7 +423,9 @@ abstract class PackedArenaObject extends ArenaObject {
 
 
 class AmountNbo extends PackedArenaObject {
-  size() { return 24; }
+  size() {
+    return 24;
+  }
 }
 
 
@@ -401,37 +436,76 @@ class EddsaPrivateKey extends PackedArenaObject {
     return obj;
   }
 
-  size() { return 32; }
+  size() {
+    return 32;
+  }
 
   getPublicKey(a?: Arena): EddsaPublicKey {
     let obj = new EddsaPublicKey(a);
     obj.nativePtr = emscAlloc.eddsa_public_key_from_private(this.nativePtr);
     return obj;
   }
+
+  static fromCrock: (string) => EddsaPrivateKey;
 }
+mixinStatic(EddsaPrivateKey, fromCrock);
 
 
-class EddsaPublicKey extends PackedArenaObject {
-  size() { return 32; }
+function fromCrock(s: string) {
+  let x = new this();
+  x.alloc();
+  x.loadCrock(s);
+  return x;
+}
+
+
+function mixin(obj, method, name?: string) {
+  if (!name) {
+    name = method.name;
+  }
+  if (!name) {
+    throw Error("Mixin needs a name.");
+  }
+  console.log("mixing in", name, "into", obj.name);
+  obj.prototype[method.name] = method;
 }
 
 
+function mixinStatic(obj, method, name?: string) {
+  if (!name) {
+    name = method.name;
+  }
+  if (!name) {
+    throw Error("Mixin needs a name.");
+  }
+  console.log("mixing in", name, "into", obj.name);
+  obj[method.name] = method;
+}
 
-class RsaBlindingKey extends ArenaObject {
-  static create(len: number, a?: Arena) {
-    let o = new RsaBlindingKey(a);
-    o.nativePtr = emscAlloc.rsa_blinding_key_create(len);
-    return o;
+
+class EddsaPublicKey extends PackedArenaObject {
+  size() {
+    return 32;
   }
-  static fromCrock(s: string, a?: Arena): RsaBlindingKey {
+  static fromCrock: (s: string) => EddsaPublicKey;
+}
+mixinStatic(EddsaPublicKey, fromCrock);
+
+function makeFromCrock(decodeFn: (p: number, s: number) => number) {
+  function fromCrock(s: string, a?: Arena) {
     let obj = new this(a);
     let buf = ByteArray.fromCrock(s);
-    obj.setNative(emscAlloc.rsa_blinding_key_decode(buf.getNative(), buf.size()));
+    obj.setNative(decodeFn(buf.getNative(),
+                           buf.size()));
     buf.destroy();
     return obj;
   }
 
-  toCrock(): string {
+  return fromCrock;
+}
+
+function makeToCrock(encodeFn: (po: number, ps: number) => number): () => string {
+  function toCrock() {
     let ptr = emscAlloc.malloc(PTR_SIZE);
     let size = emscAlloc.rsa_blinding_key_encode(this.nativePtr, ptr);
     let res = new ByteArray(size, Module.getValue(ptr, '*'));
@@ -440,15 +514,32 @@ class RsaBlindingKey extends ArenaObject {
     res.destroy();
     return s;
   }
+  return toCrock;
+}
+
+class RsaBlindingKey extends ArenaObject {
+  static create(len: number, a?: Arena) {
+    let o = new RsaBlindingKey(a);
+    o.nativePtr = emscAlloc.rsa_blinding_key_create(len);
+    return o;
+  }
+
+  static fromCrock: (s: string, a?: Arena) => RsaBlindingKey;
+  toCrock = makeToCrock(emscAlloc.rsa_blinding_key_encode);
 
   destroy() {
     // TODO
   }
 }
+mixinStatic(RsaBlindingKey, makeFromCrock(emscAlloc.rsa_blinding_key_decode));
 
 
 class HashCode extends PackedArenaObject {
-  size() { return 64; }
+  size() {
+    return 64;
+  }
+
+  static fromCrock: (s: string) => HashCode;
 
   random(qualStr: string) {
     let qual: RandomQuality;
@@ -472,11 +563,15 @@ class HashCode extends PackedArenaObject {
     emsc.hash_create_random(qual, this.nativePtr);
   }
 }
+mixinStatic(HashCode, fromCrock);
 
 
 class ByteArray extends PackedArenaObject {
   private allocatedSize: number;
-  size() { return this.allocatedSize; }
+
+  size() {
+    return this.allocatedSize;
+  }
 
   constructor(desiredSize: number, init: number, a?: Arena) {
     super(a);
@@ -510,11 +605,19 @@ class ByteArray extends PackedArenaObject {
 
 
 class EccSignaturePurpose extends PackedArenaObject {
-  size() { return this.payloadSize + 8; }
+  size() {
+    return this.payloadSize + 8;
+  }
+
   payloadSize: number;
-  constructor(purpose: SignaturePurpose, payload: PackedArenaObject, a?: Arena) {
+
+  constructor(purpose: SignaturePurpose,
+              payload: PackedArenaObject,
+              a?: Arena) {
     super(a);
-    this.nativePtr = emscAlloc.purpose_create(purpose, payload.nativePtr, payload.size());
+    this.nativePtr = emscAlloc.purpose_create(purpose,
+                                              payload.nativePtr,
+                                              payload.size());
     this.payloadSize = payload.size();
   }
 }
@@ -522,7 +625,9 @@ class EccSignaturePurpose extends PackedArenaObject {
 
 abstract class SignatureStruct {
   abstract fieldTypes(): Array<any>;
+
   abstract purpose(): SignaturePurpose;
+
   private members: any = {};
 
   constructor(x: { [name: string]: any }) {
@@ -552,12 +657,11 @@ abstract class SignatureStruct {
       ptr += size;
     }
     let ba = new ByteArray(totalSize, buf, a);
-    let x = new EccSignaturePurpose(this.purpose(), ba);
-    return x;
+    return new EccSignaturePurpose(this.purpose(), ba);
   }
 
   protected set(name: string, value: PackedArenaObject) {
-    let typemap: any = {}
+    let typemap: any = {};
     for (let f of this.fieldTypes()) {
       typemap[f[0]] = f[1];
     }
@@ -586,98 +690,156 @@ class WithdrawRequestPS extends SignatureStruct {
   constructor(w: WithdrawRequestPS_Args) {
     super(w);
   }
-  purpose() { return SignaturePurpose.RESERVE_WITHDRAW; }
+
+  purpose() {
+    return SignaturePurpose.RESERVE_WITHDRAW;
+  }
+
   fieldTypes() {
     return [
-       ["reserve_pub", EddsaPublicKey],
-       ["amount_with_fee", AmountNbo],
-       ["withdraw_fee", AmountNbo],
-       ["h_denomination_pub", HashCode],
-       ["h_coin_envelope", HashCode]];
+      ["reserve_pub", EddsaPublicKey],
+      ["amount_with_fee", AmountNbo],
+      ["withdraw_fee", AmountNbo],
+      ["h_denomination_pub", HashCode],
+      ["h_coin_envelope", HashCode]
+    ];
   }
 }
 
 
+class AbsoluteTimeNbo extends PackedArenaObject {
+  static fromTalerString(s: string): AbsoluteTimeNbo {
+    throw Error();
+  }
 
-function encodeWith(obj, fn, arena?: Arena) {
-  let ptr = emscAlloc.malloc(PTR_SIZE);
-  let len = fn(obj.getNative(), ptr);
-  let res = new ByteArray(len, null, arena);
-  res.setNative(Module.getValue(ptr, '*'));
-  emsc.free(ptr);
-  return res;
+  size() {
+    return 8;
+  }
 }
 
 
-class RsaPublicKey extends ArenaObject {
-  static fromCrock(s: string, a?: Arena): RsaPublicKey {
-    let obj = new RsaPublicKey(a);
-    let buf = ByteArray.fromCrock(s);
-    obj.nativePtr = emscAlloc.rsa_public_key_decode(buf.nativePtr, buf.size());
-    buf.destroy();
-    return obj;
+class UInt64 extends PackedArenaObject {
+  static fromNumber(n: number): UInt64 {
+    throw Error();
   }
 
-  toCrock() {
-    return this.encode().toCrock();
+  size() {
+    return 8;
   }
+}
 
-  destroy() {
-    emsc.rsa_public_key_free(this.nativePtr);
-    this.nativePtr = 0;
+
+// It's redundant, but more type safe.
+interface DepositRequestPS_Args {
+  h_contract: HashCode;
+  h_wire: HashCode;
+  timestamp: AbsoluteTimeNbo;
+  refund_deadline: AbsoluteTimeNbo;
+  transaction_id: UInt64;
+  amount_with_fee: AmountNbo;
+  deposit_fee: AmountNbo;
+  merchant: EddsaPublicKey;
+  coin_pub: EddsaPublicKey;
+}
+
+
+class DepositRequestPS extends SignatureStruct {
+  constructor(w: DepositRequestPS_Args) {
+    super(w);
+  }
+
+  purpose() {
+    return SignaturePurpose.WALLET_COIN_DEPOSIT;
   }
 
-  encode(arena?: Arena): ByteArray {
+  fieldTypes() {
+    return [
+      ["h_contract", HashCode],
+      ["h_wire", HashCode],
+      ["timestamp", AbsoluteTimeNbo],
+      ["refund_deadline", AbsoluteTimeNbo],
+      ["transaction_id", UInt64],
+      ["amount_with_fee", AmountNbo],
+      ["deposit_fee", AmountNbo],
+      ["merchant", EddsaPublicKey],
+      ["coin_pub", EddsaPublicKey],
+    ];
+  }
+}
+
+
+interface Encodeable {
+  encode(arena?: Arena): ByteArray;
+}
+
+function makeEncode(encodeFn) {
+  function encode(arena?: Arena) {
     let ptr = emscAlloc.malloc(PTR_SIZE);
-    let len = emscAlloc.rsa_public_key_encode(this.nativePtr, ptr);
-    let res = new ByteArray(len, Module.getValue(ptr, '*'), arena);
+    let len = encodeFn(this.getNative(), ptr);
+    let res = new ByteArray(len, null, arena);
+    res.setNative(Module.getValue(ptr, '*'));
     emsc.free(ptr);
     return res;
   }
+  return encode;
+}
+
+
+class RsaPublicKey extends ArenaObject implements Encodeable {
+  static fromCrock: (s: string, a?: Arena) => RsaPublicKey;
+
+  toCrock() {
+    return this.encode().toCrock();
+  }
 
+  destroy() {
+    emsc.rsa_public_key_free(this.nativePtr);
+    this.nativePtr = 0;
+  }
+
+  encode: (arena?: Arena) => ByteArray;
 }
+mixinStatic(RsaPublicKey, makeFromCrock(emscAlloc.rsa_public_key_decode));
+mixin(RsaPublicKey, makeEncode(emscAlloc.rsa_public_key_encode));
 
 
 class EddsaSignature extends PackedArenaObject {
-  size() { return 64; }
+  size() {
+    return 64;
+  }
 }
 
 
-class RsaSignature extends ArenaObject {
-  static fromCrock(s: string, a?: Arena): RsaSignature {
-    let obj = new this(a);
-    let buf = ByteArray.fromCrock(s);
-    obj.setNative(emscAlloc.rsa_signature_decode(buf.getNative(), buf.size()));
-    buf.destroy();
-    return obj;
-  }
+class RsaSignature extends ArenaObject implements Encodeable{
+  static fromCrock: (s: string, a?: Arena) => RsaSignature;
 
-  encode(arena?: Arena): ByteArray {
-    return encodeWith(this, emscAlloc.rsa_signature_encode);
-  }
+  encode: (arena?: Arena) => ByteArray;
 
   destroy() {
     emsc.rsa_signature_free(this.getNative());
     this.setNative(0);
   }
 }
+mixinStatic(RsaSignature, makeFromCrock(emscAlloc.rsa_signature_decode));
+mixin(RsaSignature, makeEncode(emscAlloc.rsa_signature_encode));
+
 
 function rsaBlind(hashCode: HashCode,
-                  blindingKey: RsaBlindingKey, 
+                  blindingKey: RsaBlindingKey,
                   pkey: RsaPublicKey,
-                  arena?: Arena): ByteArray
-{
+                  arena?: Arena): ByteArray {
   let ptr = emscAlloc.malloc(PTR_SIZE);
-  let s = emscAlloc.rsa_blind(hashCode.nativePtr, blindingKey.nativePtr, pkey.nativePtr, ptr);
-  let res = new ByteArray(s, Module.getValue(ptr, '*'), arena);
-  return res;
+  let s = emscAlloc.rsa_blind(hashCode.nativePtr,
+                              blindingKey.nativePtr,
+                              pkey.nativePtr,
+                              ptr);
+  return new ByteArray(s, Module.getValue(ptr, '*'), arena);
 }
 
 
 function eddsaSign(purpose: EccSignaturePurpose,
                    priv: EddsaPrivateKey,
-                   a?: Arena): EddsaSignature
-{
+                   a?: Arena): EddsaSignature {
   let sig = new EddsaSignature(a);
   sig.alloc();
   let res = emsc.eddsa_sign(priv.nativePtr, purpose.nativePtr, sig.nativePtr);
@@ -687,13 +849,14 @@ function eddsaSign(purpose: EccSignaturePurpose,
   return sig;
 }
 
+
 function rsaUnblind(sig: RsaSignature,
                     bk: RsaBlindingKey,
                     pk: RsaPublicKey,
                     a?: Arena): RsaSignature {
   let x = new RsaSignature(a);
-  x.nativePtr = emscAlloc.rsa_unblind(sig.nativePtr, bk.nativePtr, pk.nativePtr);
+  x.nativePtr = emscAlloc.rsa_unblind(sig.nativePtr,
+                                      bk.nativePtr,
+                                      pk.nativePtr);
   return x;
 }
-
-
diff --git a/extension/background/libwrapper.js b/extension/background/libwrapper.js
index 46d198372..791359a25 100644
--- a/extension/background/libwrapper.js
+++ b/extension/background/libwrapper.js
@@ -8890,85 +8890,73 @@ function _TALER_WR_multiply_amount($a,$factor) {
 function _TALER_WR_multiply_amounts($a,$b) {
  $a = $a|0;
  $b = $b|0;
- var $0 = 0.0, $1 = 0, $10 = 0, $11 = 0, $12 = 0, $13 = 0.0, $14 = 0.0, $15 = 0, $16 = 0, $17 = 0, $18 = 0, $19 = 0, $2 = 0, $20 = 0, $21 = 0, $22 = 0.0, $23 = 0.0, $24 = 0.0, $25 = 0, $26 = 0;
- var $27 = 0, $28 = 0, $29 = 0, $3 = 0, $30 = 0, $31 = 0, $32 = 0.0, $33 = 0.0, $34 = 0.0, $35 = 0.0, $36 = 0.0, $37 = 0.0, $38 = 0.0, $39 = 0, $4 = 0, $40 = 0.0, $41 = 0, $42 = 0.0, $43 = 0.0, $44 = 0.0;
- var $45 = 0, $46 = 0.0, $47 = 0.0, $48 = 0.0, $49 = 0, $5 = 0, $50 = 0.0, $51 = 0.0, $6 = 0, $7 = 0, $8 = 0.0, $9 = 0.0, $ad = 0.0, $bd = 0.0, $or$cond = 0, $ret = 0.0, label = 0, sp = 0;
+ var $0 = 0.0, $1 = 0, $10 = 0, $11 = 0, $12 = 0.0, $13 = 0.0, $14 = 0, $15 = 0, $16 = 0, $17 = 0.0, $18 = 0.0, $19 = 0, $2 = 0, $20 = 0, $21 = 0, $22 = 0, $23 = 0, $24 = 0, $25 = 0, $26 = 0.0;
+ var $27 = 0.0, $28 = 0.0, $29 = 0, $3 = 0, $30 = 0, $31 = 0, $32 = 0, $33 = 0, $34 = 0, $35 = 0, $36 = 0.0, $37 = 0.0, $38 = 0.0, $39 = 0.0, $4 = 0, $40 = 0.0, $41 = 0.0, $42 = 0.0, $43 = 0.0, $5 = 0;
+ var $6 = 0, $7 = 0, $8 = 0, $9 = 0, $ad = 0.0, $bd = 0.0, $ret = 0.0, label = 0, sp = 0;
  sp = STACKTOP;
  STACKTOP = STACKTOP + 48|0; if ((STACKTOP|0) >= (STACK_MAX|0)) abort();
  $1 = $a;
  $2 = $b;
  $3 = $1;
- (_TALER_amount_normalize($3)|0);
- $4 = $2;
- (_TALER_amount_normalize($4)|0);
- $5 = $1;
- $6 = ((($5)) + 8|0);
- $7 = HEAP32[$6>>2]|0;
- $8 = (+($7>>>0));
- $9 = $8 / 1.0E+6;
- $ad = $9;
- $10 = $2;
- $11 = ((($10)) + 8|0);
- $12 = HEAP32[$11>>2]|0;
- $13 = (+($12>>>0));
- $14 = $13 / 1.0E+6;
- $bd = $14;
- $15 = $1;
- $16 = $15;
- $17 = $16;
- $18 = HEAP32[$17>>2]|0;
- $19 = (($16) + 4)|0;
- $20 = $19;
- $21 = HEAP32[$20>>2]|0;
- $22 = (+($18>>>0)) + (4294967296.0*(+($21>>>0)));
- $23 = $ad;
- $24 = $23 + $22;
- $ad = $24;
- $25 = $2;
- $26 = $25;
- $27 = $26;
- $28 = HEAP32[$27>>2]|0;
- $29 = (($26) + 4)|0;
- $30 = $29;
- $31 = HEAP32[$30>>2]|0;
- $32 = (+($28>>>0)) + (4294967296.0*(+($31>>>0)));
- $33 = $bd;
- $34 = $33 + $32;
- $bd = $34;
- $35 = $ad;
- $36 = $bd;
- $37 = $35 * $36;
- $ret = $37;
- $38 = $ad;
- $39 = $38 < 1.0;
- $40 = $bd;
- $41 = $40 < 1.0;
- $or$cond = $39 | $41;
- $42 = $ret;
- $43 = $ad;
- $44 = $bd;
- $45 = $43 > $44;
- $46 = $ad;
- $47 = $bd;
- $48 = $45 ? $46 : $47;
- $49 = $42 < $48;
- if ($or$cond) {
-  if (!($49)) {
-   $0 = -1.0;
-   $51 = $0;
-   STACKTOP = sp;return (+$51);
-  }
+ $4 = (_TALER_amount_normalize($3)|0);
+ $5 = (-1)==($4|0);
+ if ($5) {
+  $0 = -1.0;
+  $43 = $0;
+  STACKTOP = sp;return (+$43);
+ }
+ $6 = $2;
+ $7 = (_TALER_amount_normalize($6)|0);
+ $8 = (-1)==($7|0);
+ if ($8) {
+  $0 = -1.0;
+  $43 = $0;
+  STACKTOP = sp;return (+$43);
  } else {
-  if ($49) {
-   $0 = -1.0;
-   $51 = $0;
-   STACKTOP = sp;return (+$51);
-  }
+  $9 = $1;
+  $10 = ((($9)) + 8|0);
+  $11 = HEAP32[$10>>2]|0;
+  $12 = (+($11>>>0));
+  $13 = $12 / 1.0E+6;
+  $ad = $13;
+  $14 = $2;
+  $15 = ((($14)) + 8|0);
+  $16 = HEAP32[$15>>2]|0;
+  $17 = (+($16>>>0));
+  $18 = $17 / 1.0E+6;
+  $bd = $18;
+  $19 = $1;
+  $20 = $19;
+  $21 = $20;
+  $22 = HEAP32[$21>>2]|0;
+  $23 = (($20) + 4)|0;
+  $24 = $23;
+  $25 = HEAP32[$24>>2]|0;
+  $26 = (+($22>>>0)) + (4294967296.0*(+($25>>>0)));
+  $27 = $ad;
+  $28 = $27 + $26;
+  $ad = $28;
+  $29 = $2;
+  $30 = $29;
+  $31 = $30;
+  $32 = HEAP32[$31>>2]|0;
+  $33 = (($30) + 4)|0;
+  $34 = $33;
+  $35 = HEAP32[$34>>2]|0;
+  $36 = (+($32>>>0)) + (4294967296.0*(+($35>>>0)));
+  $37 = $bd;
+  $38 = $37 + $36;
+  $bd = $38;
+  $39 = $ad;
+  $40 = $bd;
+  $41 = $39 * $40;
+  $ret = $41;
+  $42 = $ret;
+  $0 = $42;
+  $43 = $0;
+  STACKTOP = sp;return (+$43);
  }
- $50 = $ret;
- $0 = $50;
- $51 = $0;
- STACKTOP = sp;return (+$51);
+ return +(0.0);
 }
 function _GNUNET_xmalloc_($size,$filename,$linenumber) {
  $size = $size|0;
@@ -145293,7 +145281,7 @@ var FUNCTION_TABLE_viiii = [b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,
 ,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,b10,_reporter,b10,b10
 ,b10,b10,b10,b10,b10];
 
-  return { _WRALL_make_purpose: _WRALL_make_purpose, _GNUNET_CRYPTO_rsa_blinding_key_encode: _GNUNET_CRYPTO_rsa_blinding_key_encode, _bitshift64Lshr: _bitshift64Lshr, _bitshift64Ashr: _bitshift64Ashr, _GNUNET_CRYPTO_eddsa_key_create: _GNUNET_CRYPTO_eddsa_key_create, _memcpy: _memcpy, _TALER_WR_GNUNET_free: _TALER_WR_GNUNET_free, _TALER_WRALL_amount_add: _TALER_WRALL_amount_add, _GNUNET_CRYPTO_rsa_private_key_decode: _GNUNET_CRYPTO_rsa_private_key_decode, _TALER_WR_multiply_amount: _TALER_WR_multiply_amount, _GNUNET_CRYPTO_rsa_blinding_key_decode: _GNUNET_CRYPTO_rsa_blinding_key_decode, _GNUNET_CRYPTO_ecc_ecdh: _GNUNET_CRYPTO_ecc_ecdh, _TALER_amount_hton: _TALER_amount_hton, _TALER_WR_verify_sign_key_enc: _TALER_WR_verify_sign_key_enc, _free: _free, _TALER_WRALL_sign_deposit_permission: _TALER_WRALL_sign_deposit_permission, _TALER_WR_verify_denoms: _TALER_WR_verify_denoms, _GNUNET_CRYPTO_rsa_blinding_key_create: _GNUNET_CRYPTO_rsa_blinding_key_create, _TALER_WR_verify_sign_key: _TALER_WR_verify_sign_key, _TALER_WRALL_rsa_public_key_hash: _TALER_WRALL_rsa_public_key_hash, _TALER_WRALL_gen_key_from_blob: _TALER_WRALL_gen_key_from_blob, _GNUNET_CRYPTO_rsa_private_key_get_public: _GNUNET_CRYPTO_rsa_private_key_get_public, _TALER_WRALL_rsa_public_key_decode_from_string: _TALER_WRALL_rsa_public_key_decode_from_string, _GNUNET_CRYPTO_symmetric_encrypt: _GNUNET_CRYPTO_symmetric_encrypt, _TALER_WR_get_fraction: _TALER_WR_get_fraction, _TALER_WR_verify_denoms_enc: _TALER_WR_verify_denoms_enc, _TALER_amount_cmp: _TALER_amount_cmp, _TALER_WRALL_ecdhe_public_key_from_private_key: _TALER_WRALL_ecdhe_public_key_from_private_key, _llvm_cttz_i32: _llvm_cttz_i32, _TALER_WRALL_eddsa_private_key_from_string: _TALER_WRALL_eddsa_private_key_from_string, _TALER_WRALL_gen_init_vector: _TALER_WRALL_gen_init_vector, _TALER_amount_ntoh: _TALER_amount_ntoh, _WR_verify_test: _WR_verify_test, _GNUNET_CRYPTO_rsa_public_key_free: _GNUNET_CRYPTO_rsa_public_key_free, _GNUNET_CRYPTO_hkdf: _GNUNET_CRYPTO_hkdf, _GNUNET_CRYPTO_eddsa_key_get_public: _GNUNET_CRYPTO_eddsa_key_get_public, _llvm_bswap_i32: _llvm_bswap_i32, _GNUNET_CRYPTO_rsa_private_key_create: _GNUNET_CRYPTO_rsa_private_key_create, _GNUNET_STRINGS_data_to_string_alloc: _GNUNET_STRINGS_data_to_string_alloc, _TALER_WRALL_sign_test: _TALER_WRALL_sign_test, _TALER_WR_verify_confirmation: _TALER_WR_verify_confirmation, _GNUNET_CRYPTO_rsa_public_key_decode: _GNUNET_CRYPTO_rsa_public_key_decode, _GNUNET_CRYPTO_rsa_blinding_key_free: _GNUNET_CRYPTO_rsa_blinding_key_free, _GNUNET_CRYPTO_rsa_signature_encode: _GNUNET_CRYPTO_rsa_signature_encode, _GNUNET_CRYPTO_rsa_verify: _GNUNET_CRYPTO_rsa_verify, _TALER_WR_eddsa_verify: _TALER_WR_eddsa_verify, _GNUNET_STRINGS_string_to_data: _GNUNET_STRINGS_string_to_data, _TALER_WRALL_gen_symmetric_key: _TALER_WRALL_gen_symmetric_key, _TALER_WRALL_ecc_ecdh: _TALER_WRALL_ecc_ecdh, _memset: _memset, _GNUNET_CRYPTO_rsa_unblind: _GNUNET_CRYPTO_rsa_unblind, _TALER_WR_get_currency: _TALER_WR_get_currency, _DEBUG_WR_get_purpose: _DEBUG_WR_get_purpose, _TALER_WRALL_get_amount: _TALER_WRALL_get_amount, _GNUNET_CRYPTO_rsa_private_key_encode: _GNUNET_CRYPTO_rsa_private_key_encode, _GNUNET_CRYPTO_symmetric_decrypt: _GNUNET_CRYPTO_symmetric_decrypt, _i64Subtract: _i64Subtract, _TALER_WR_get_value: _TALER_WR_get_value, _GNUNET_CRYPTO_rsa_signature_free: _GNUNET_CRYPTO_rsa_signature_free, _TALER_WRALL_eddsa_public_key_from_priv_string: _TALER_WRALL_eddsa_public_key_from_priv_string, _GNUNET_CRYPTO_rsa_blind: _GNUNET_CRYPTO_rsa_blind, _TALER_WR_verify_denom_enc: _TALER_WR_verify_denom_enc, _malloc: _malloc, _TALER_WR_hello_world: _TALER_WR_hello_world, _TALER_WRALL_make_withdraw_bundle: _TALER_WRALL_make_withdraw_bundle, _GNUNET_CRYPTO_rsa_signature_decode: _GNUNET_CRYPTO_rsa_signature_decode, _GNUNET_CRYPTO_rsa_sign: _GNUNET_CRYPTO_rsa_sign, _GNUNET_CRYPTO_ecdhe_key_create: _GNUNET_CRYPTO_ecdhe_key_create, _TALER_WRALL_get_encoding_from_rsa_signature: _TALER_WRALL_get_encoding_from_rsa_signature, _TALER_WRALL_hash: _TALER_WRALL_hash, _TALER_amount_normalize: _TALER_amount_normalize, _TALER_WRALL_sign_contract: _TALER_WRALL_sign_contract, _bitshift64Shl: _bitshift64Shl, _GNUNET_CRYPTO_rsa_private_key_free: _GNUNET_CRYPTO_rsa_private_key_free, _fflush: _fflush, _GNUNET_CRYPTO_hash_create_random: _GNUNET_CRYPTO_hash_create_random, _TALER_WRALL_eddsa_public_key_from_private: _TALER_WRALL_eddsa_public_key_from_private, _TALER_WR_multiply_amounts: _TALER_WR_multiply_amounts, _TALER_amount_add: _TALER_amount_add, _GNUNET_CRYPTO_ecdhe_key_get_public: _GNUNET_CRYPTO_ecdhe_key_get_public, _TALER_amount_subtract: _TALER_amount_subtract, _i64Add: _i64Add, _TALER_WRALL_purpose_create: _TALER_WRALL_purpose_create, _GNUNET_CRYPTO_eddsa_sign: _GNUNET_CRYPTO_eddsa_sign, _TALER_WR_verify_denom: _TALER_WR_verify_denom, _TALER_WRALL_get_current_time: _TALER_WRALL_get_current_time, ___errno_location: ___errno_location, _TALER_WR_get_fancy_time: _TALER_WR_get_fancy_time, _TALER_WRALL_make_eddsa_signature: _TALER_WRALL_make_eddsa_signature, _memmove: _memmove, _DEBUG_WR_dump_amount: _DEBUG_WR_dump_amount, _GNUNET_CRYPTO_rsa_public_key_encode: _GNUNET_CRYPTO_rsa_public_key_encode, _GNUNET_CRYPTO_hash: _GNUNET_CRYPTO_hash, _GNUNET_util_cl_init: _GNUNET_util_cl_init, _GNUNET_CRYPTO_random_init: _GNUNET_CRYPTO_random_init, _gpg_err_init: _gpg_err_init, runPostSets: runPostSets, stackAlloc: stackAlloc, stackSave: stackSave, stackRestore: stackRestore, establishStackSpace: establishStackSpace, setThrew: setThrew, setTempRet0: setTempRet0, getTempRet0: getTempRet0, dynCall_iiii: dynCall_iiii, dynCall_viiiii: dynCall_viiiii, dynCall_vi: dynCall_vi, dynCall_vii: dynCall_vii, dynCall_ii: dynCall_ii, dynCall_viii: dynCall_viii, dynCall_v: dynCall_v, dynCall_iiiii: dynCall_iiiii, dynCall_viiiiii: dynCall_viiiiii, dynCall_iii: dynCall_iii, dynCall_viiii: dynCall_viiii };
+  return { _WRALL_make_purpose: _WRALL_make_purpose, _GNUNET_CRYPTO_rsa_blinding_key_encode: _GNUNET_CRYPTO_rsa_blinding_key_encode, _bitshift64Lshr: _bitshift64Lshr, _bitshift64Ashr: _bitshift64Ashr, _GNUNET_CRYPTO_eddsa_key_create: _GNUNET_CRYPTO_eddsa_key_create, _memcpy: _memcpy, _TALER_WR_GNUNET_free: _TALER_WR_GNUNET_free, _TALER_WRALL_amount_add: _TALER_WRALL_amount_add, _GNUNET_CRYPTO_rsa_private_key_decode: _GNUNET_CRYPTO_rsa_private_key_decode, _TALER_WR_multiply_amount: _TALER_WR_multiply_amount, _GNUNET_CRYPTO_rsa_blinding_key_decode: _GNUNET_CRYPTO_rsa_blinding_key_decode, _GNUNET_CRYPTO_ecc_ecdh: _GNUNET_CRYPTO_ecc_ecdh, _TALER_amount_hton: _TALER_amount_hton, _TALER_WR_verify_sign_key_enc: _TALER_WR_verify_sign_key_enc, _free: _free, _TALER_WRALL_sign_deposit_permission: _TALER_WRALL_sign_deposit_permission, _TALER_WR_verify_denoms: _TALER_WR_verify_denoms, _GNUNET_CRYPTO_rsa_blinding_key_create: _GNUNET_CRYPTO_rsa_blinding_key_create, _TALER_WR_verify_sign_key: _TALER_WR_verify_sign_key, _TALER_WRALL_rsa_public_key_hash: _TALER_WRALL_rsa_public_key_hash, _TALER_WRALL_gen_key_from_blob: _TALER_WRALL_gen_key_from_blob, _GNUNET_CRYPTO_rsa_private_key_get_public: _GNUNET_CRYPTO_rsa_private_key_get_public, _TALER_WRALL_rsa_public_key_decode_from_string: _TALER_WRALL_rsa_public_key_decode_from_string, _GNUNET_CRYPTO_symmetric_encrypt: _GNUNET_CRYPTO_symmetric_encrypt, _TALER_WR_get_fraction: _TALER_WR_get_fraction, _TALER_WR_verify_denoms_enc: _TALER_WR_verify_denoms_enc, _TALER_amount_cmp: _TALER_amount_cmp, _TALER_WRALL_ecdhe_public_key_from_private_key: _TALER_WRALL_ecdhe_public_key_from_private_key, _llvm_cttz_i32: _llvm_cttz_i32, _TALER_WRALL_eddsa_private_key_from_string: _TALER_WRALL_eddsa_private_key_from_string, _TALER_WRALL_gen_init_vector: _TALER_WRALL_gen_init_vector, _TALER_amount_ntoh: _TALER_amount_ntoh, _WR_verify_test: _WR_verify_test, _GNUNET_CRYPTO_rsa_public_key_free: _GNUNET_CRYPTO_rsa_public_key_free, _GNUNET_CRYPTO_hkdf: _GNUNET_CRYPTO_hkdf, _GNUNET_CRYPTO_eddsa_key_get_public: _GNUNET_CRYPTO_eddsa_key_get_public, _llvm_bswap_i32: _llvm_bswap_i32, _GNUNET_CRYPTO_rsa_private_key_create: _GNUNET_CRYPTO_rsa_private_key_create, _GNUNET_STRINGS_data_to_string_alloc: _GNUNET_STRINGS_data_to_string_alloc, _TALER_WRALL_sign_test: _TALER_WRALL_sign_test, _TALER_WR_verify_confirmation: _TALER_WR_verify_confirmation, _GNUNET_CRYPTO_rsa_public_key_decode: _GNUNET_CRYPTO_rsa_public_key_decode, _GNUNET_CRYPTO_rsa_blinding_key_free: _GNUNET_CRYPTO_rsa_blinding_key_free, _GNUNET_CRYPTO_rsa_signature_encode: _GNUNET_CRYPTO_rsa_signature_encode, _GNUNET_CRYPTO_rsa_verify: _GNUNET_CRYPTO_rsa_verify, _TALER_WR_eddsa_verify: _TALER_WR_eddsa_verify, _GNUNET_STRINGS_string_to_data: _GNUNET_STRINGS_string_to_data, _TALER_WRALL_gen_symmetric_key: _TALER_WRALL_gen_symmetric_key, _TALER_WRALL_ecc_ecdh: _TALER_WRALL_ecc_ecdh, _memset: _memset, _GNUNET_CRYPTO_rsa_unblind: _GNUNET_CRYPTO_rsa_unblind, _TALER_WR_get_currency: _TALER_WR_get_currency, _DEBUG_WR_get_purpose: _DEBUG_WR_get_purpose, _TALER_WRALL_get_amount: _TALER_WRALL_get_amount, _GNUNET_CRYPTO_rsa_private_key_encode: _GNUNET_CRYPTO_rsa_private_key_encode, _GNUNET_CRYPTO_symmetric_decrypt: _GNUNET_CRYPTO_symmetric_decrypt, _i64Subtract: _i64Subtract, _TALER_WR_get_value: _TALER_WR_get_value, _GNUNET_CRYPTO_rsa_signature_free: _GNUNET_CRYPTO_rsa_signature_free, _TALER_WRALL_eddsa_public_key_from_priv_string: _TALER_WRALL_eddsa_public_key_from_priv_string, _GNUNET_CRYPTO_rsa_blind: _GNUNET_CRYPTO_rsa_blind, _TALER_WR_verify_denom_enc: _TALER_WR_verify_denom_enc, _malloc: _malloc, _TALER_WR_hello_world: _TALER_WR_hello_world, _TALER_WRALL_make_withdraw_bundle: _TALER_WRALL_make_withdraw_bundle, _GNUNET_CRYPTO_rsa_signature_decode: _GNUNET_CRYPTO_rsa_signature_decode, _GNUNET_CRYPTO_rsa_sign: _GNUNET_CRYPTO_rsa_sign, _GNUNET_CRYPTO_ecdhe_key_create: _GNUNET_CRYPTO_ecdhe_key_create, _TALER_WRALL_get_encoding_from_rsa_signature: _TALER_WRALL_get_encoding_from_rsa_signature, _TALER_WRALL_hash: _TALER_WRALL_hash, _TALER_amount_normalize: _TALER_amount_normalize, _TALER_WRALL_sign_contract: _TALER_WRALL_sign_contract, _bitshift64Shl: _bitshift64Shl, _GNUNET_CRYPTO_rsa_private_key_free: _GNUNET_CRYPTO_rsa_private_key_free, _fflush: _fflush, _GNUNET_CRYPTO_hash_create_random: _GNUNET_CRYPTO_hash_create_random, _TALER_WRALL_eddsa_public_key_from_private: _TALER_WRALL_eddsa_public_key_from_private, _TALER_WR_multiply_amounts: _TALER_WR_multiply_amounts, _TALER_amount_add: _TALER_amount_add, _GNUNET_CRYPTO_ecdhe_key_get_public: _GNUNET_CRYPTO_ecdhe_key_get_public, _TALER_amount_subtract: _TALER_amount_subtract, _i64Add: _i64Add, _TALER_WRALL_purpose_create: _TALER_WRALL_purpose_create, _GNUNET_CRYPTO_eddsa_sign: _GNUNET_CRYPTO_eddsa_sign, _TALER_WR_verify_denom: _TALER_WR_verify_denom, _TALER_WRALL_get_current_time: _TALER_WRALL_get_current_time, ___errno_location: ___errno_location, _TALER_WR_get_fancy_time: _TALER_WR_get_fancy_time, _TALER_WRALL_make_eddsa_signature: _TALER_WRALL_make_eddsa_signature, _memmove: _memmove, _TALER_amount_get_zero: _TALER_amount_get_zero, _DEBUG_WR_dump_amount: _DEBUG_WR_dump_amount, _GNUNET_CRYPTO_rsa_public_key_encode: _GNUNET_CRYPTO_rsa_public_key_encode, _GNUNET_CRYPTO_hash: _GNUNET_CRYPTO_hash, _GNUNET_util_cl_init: _GNUNET_util_cl_init, _GNUNET_CRYPTO_random_init: _GNUNET_CRYPTO_random_init, _gpg_err_init: _gpg_err_init, runPostSets: runPostSets, stackAlloc: stackAlloc, stackSave: stackSave, stackRestore: stackRestore, establishStackSpace: establishStackSpace, setThrew: setThrew, setTempRet0: setTempRet0, getTempRet0: getTempRet0, dynCall_iiii: dynCall_iiii, dynCall_viiiii: dynCall_viiiii, dynCall_vi: dynCall_vi, dynCall_vii: dynCall_vii, dynCall_ii: dynCall_ii, dynCall_viii: dynCall_viii, dynCall_v: dynCall_v, dynCall_iiiii: dynCall_iiiii, dynCall_viiiiii: dynCall_viiiiii, dynCall_iii: dynCall_iii, dynCall_viiii: dynCall_viiii };
 })
 // EMSCRIPTEN_END_ASM
 (Module.asmGlobalArg, Module.asmLibraryArg, buffer);
@@ -145843,6 +145831,12 @@ assert(!runtimeExited, 'the runtime was exited (use NO_EXIT_RUNTIME to keep it a
 return real__GNUNET_CRYPTO_random_init.apply(null, arguments);
 };
 
+var real__TALER_amount_get_zero = asm["_TALER_amount_get_zero"]; asm["_TALER_amount_get_zero"] = function() {
+assert(runtimeInitialized, 'you need to wait for the runtime to be ready (e.g. wait for main() to be called)');
+assert(!runtimeExited, 'the runtime was exited (use NO_EXIT_RUNTIME to keep it alive after main() exits)');
+return real__TALER_amount_get_zero.apply(null, arguments);
+};
+
 var real__DEBUG_WR_dump_amount = asm["_DEBUG_WR_dump_amount"]; asm["_DEBUG_WR_dump_amount"] = function() {
 assert(runtimeInitialized, 'you need to wait for the runtime to be ready (e.g. wait for main() to be called)');
 assert(!runtimeExited, 'the runtime was exited (use NO_EXIT_RUNTIME to keep it alive after main() exits)');
@@ -145954,6 +145948,7 @@ var _TALER_WR_get_fancy_time = Module["_TALER_WR_get_fancy_time"] = asm["_TALER_
 var _TALER_WRALL_make_eddsa_signature = Module["_TALER_WRALL_make_eddsa_signature"] = asm["_TALER_WRALL_make_eddsa_signature"];
 var _memmove = Module["_memmove"] = asm["_memmove"];
 var _GNUNET_CRYPTO_random_init = Module["_GNUNET_CRYPTO_random_init"] = asm["_GNUNET_CRYPTO_random_init"];
+var _TALER_amount_get_zero = Module["_TALER_amount_get_zero"] = asm["_TALER_amount_get_zero"];
 var _DEBUG_WR_dump_amount = Module["_DEBUG_WR_dump_amount"] = asm["_DEBUG_WR_dump_amount"];
 var _GNUNET_CRYPTO_rsa_public_key_encode = Module["_GNUNET_CRYPTO_rsa_public_key_encode"] = asm["_GNUNET_CRYPTO_rsa_public_key_encode"];
 var _TALER_WRALL_get_current_time = Module["_TALER_WRALL_get_current_time"] = asm["_TALER_WRALL_get_current_time"];
diff --git a/extension/background/wallet.js b/extension/background/wallet.js
index 3bcbde91b..f915187ab 100644
--- a/extension/background/wallet.js
+++ b/extension/background/wallet.js
@@ -1,38 +1,6 @@
 /// <reference path="../decl/urijs/URIjs.d.ts" />
 /// <reference path="../decl/chrome/chrome.d.ts" />
 'use strict';
-const DB_NAME = "taler";
-const DB_VERSION = 1;
-/**
- * Return a promise that resolves
- * to the taler wallet db.
- */
-function openTalerDb() {
-    return new Promise((resolve, reject) => {
-        let req = indexedDB.open(DB_NAME, DB_VERSION);
-        req.onerror = (e) => {
-            reject(e);
-        };
-        req.onsuccess = (e) => {
-            resolve(req.result);
-        };
-        req.onupgradeneeded = (e) => {
-            let db = req.result;
-            console.log("DB: upgrade needed: oldVersion = " + e.oldVersion);
-            switch (e.oldVersion) {
-                case 0:
-                    db.createObjectStore("mints", { keyPath: "baseUrl" });
-                    db.createObjectStore("reserves", { keyPath: "reserve_pub" });
-                    db.createObjectStore("denoms", { keyPath: "denomPub" });
-                    let coins = db.createObjectStore("coins", { keyPath: "coinPub" });
-                    coins.createIndex("mintBaseUrl", "mintBaseUrl");
-                    db.createObjectStore("transactions", { keyPath: "contractHash" });
-                    db.createObjectStore("precoins", { keyPath: "coinPub", autoIncrement: true });
-                    break;
-            }
-        };
-    });
-}
 /**
  * See http://api.taler.net/wallet.html#general
  */
@@ -46,8 +14,141 @@ function canonicalizeBaseUrl(url) {
     x.query();
     return x.href();
 }
-function grantCoins(db, feeThreshold, paymentAmount, mintBaseUrl) {
-    throw "not implemented";
+function signDeposit(db, offer, cds) {
+    let ret = [];
+    let amountSpent = Amount.getZero(cds[0].coin.currentAmount.currency);
+    let amountRemaining = new Amount(offer.contract.amount);
+    cds = copy(cds);
+    for (let cd of cds) {
+        let coinSpend;
+        if (amountRemaining.cmp(new Amount(cd.coin.currentAmount)) < 0) {
+            coinSpend = new Amount(amountRemaining.toJson());
+        }
+        else {
+            coinSpend = new Amount(cd.coin.currentAmount);
+        }
+        let d = new DepositRequestPS({
+            h_contract: HashCode.fromCrock(offer.H_contract),
+            h_wire: HashCode.fromCrock(offer.contract.H_wire),
+            amount_with_fee: new Amount(cd.coin.currentAmount).toNbo(),
+            coin_pub: EddsaPublicKey.fromCrock(cd.coin.coinPub),
+            deposit_fee: new Amount(cd.denom.fee_deposit).toNbo(),
+            merchant: EddsaPublicKey.fromCrock(offer.contract.merchant_pub),
+            refund_deadline: AbsoluteTimeNbo.fromTalerString(offer.contract.refund_deadline),
+            timestamp: AbsoluteTimeNbo.fromTalerString(offer.contract.timestamp),
+            transaction_id: UInt64.fromNumber(offer.contract.transaction_id),
+        });
+        amountSpent.add(coinSpend);
+        let newAmount = new Amount(cd.coin.currentAmount);
+        newAmount.sub(coinSpend);
+        cd.coin.currentAmount = newAmount.toJson();
+        let coinSig = eddsaSign(d.toPurpose(), EddsaPrivateKey.fromCrock(cd.coin.coinPriv))
+            .toCrock();
+        let s = {
+            coin_sig: coinSig,
+            coin_pub: cd.coin.coinPub,
+            ub_sig: cd.coin.denomSig,
+            denom_pub: cd.coin.denomPub,
+            f: amountSpent.toJson(),
+        };
+        ret.push({ sig: coinSig, updatedCoin: cd.coin });
+    }
+    return ret;
+}
+/**
+ * Get mints and associated coins that are still spendable,
+ * but only if the sum the coins' remaining value exceeds the payment amount.
+ * @param db
+ * @param paymentAmount
+ * @param depositFeeLimit
+ * @param mintKeys
+ */
+function getPossibleMintCoins(db, paymentAmount, depositFeeLimit, allowedMints) {
+    return new Promise((resolve, reject) => {
+        let m = {};
+        let found = false;
+        let tx = db.transaction(["mints", "coins"]);
+        // First pass: Get all coins from acceptable mints.
+        for (let info of allowedMints) {
+            let req_mints = tx.objectStore("mints")
+                .index("pubKey")
+                .get(info.master_pub);
+            req_mints.onsuccess = (e) => {
+                let mint = req_mints.result;
+                let req_coins = tx.objectStore("coins")
+                    .index("mintBaseUrl")
+                    .openCursor(IDBKeyRange.only(mint.baseUrl));
+                req_coins.onsuccess = (e) => {
+                    let cursor = req_coins.result;
+                    if (!cursor) {
+                        return;
+                    }
+                    let cd = {
+                        coin: cursor.value,
+                        denom: mint.keys.denoms[cursor.value.denomPub]
+                    };
+                    let x = m[mint.baseUrl];
+                    if (!x) {
+                        m[mint.baseUrl] = [cd];
+                    }
+                    else {
+                        x.push(cd);
+                    }
+                };
+            };
+        }
+        tx.oncomplete = (e) => {
+            let ret = {};
+            nextMint: for (let key in m) {
+                let coins = m[key].map((x) => ({
+                    a: new Amount(x.denom.fee_deposit),
+                    c: x
+                }));
+                // Sort by ascending deposit fee
+                coins.sort((o1, o2) => o1.a.cmp(o2.a));
+                let maxFee = new Amount(depositFeeLimit);
+                let minAmount = new Amount(paymentAmount);
+                let accFee = new Amount(coins[0].c.denom.fee_deposit);
+                let accAmount = new Amount(coins[0].c.coin.currentAmount);
+                for (let i = 0; i < coins.length; i++) {
+                    if (accFee.cmp(maxFee) >= 0) {
+                        continue nextMint;
+                    }
+                    if (accAmount.cmp(minAmount) >= 0) {
+                        ret[key] = m[key];
+                        continue nextMint;
+                    }
+                    accFee.add(coins[i].a);
+                    accFee.add(new Amount(coins[i].c.coin.currentAmount));
+                }
+            }
+            resolve(ret);
+        };
+        tx.onerror = (e) => {
+            reject();
+        };
+    });
+}
+function executePay(db, offer, payCoinInfo, merchantBaseUrl, chosenMint) {
+    return new Promise((resolve, reject) => {
+        let reqData = {};
+        reqData["H_wire"] = offer.contract.H_wire;
+        reqData["H_contract"] = offer.H_contract;
+        reqData["transaction_id"] = offer.contract.transaction_id;
+        reqData["refund_deadline"] = offer.contract.refund_deadline;
+        reqData["mint"] = chosenMint;
+        reqData["coins"] = payCoinInfo.map((x) => x.sig);
+        let payUrl = URI(merchantBaseUrl).absoluteTo(merchantBaseUrl);
+        console.log("Merchant URL", payUrl);
+        let req = new XMLHttpRequest();
+        req.open('post', payUrl.href());
+        req.setRequestHeader("Content-Type", "application/json;charset=UTF-8");
+        req.addEventListener('readystatechange', (e) => {
+            if (req.readyState == XMLHttpRequest.DONE) {
+                resolve();
+            }
+        });
+    });
 }
 function confirmPay(db, detail, sendResponse) {
     console.log("confirmPay", JSON.stringify(detail));
@@ -57,10 +158,17 @@ function confirmPay(db, detail, sendResponse) {
         contract: detail.offer.contract,
         sig: detail.offer
     };
-    let contract = detail.offer.contract;
-    //let chosenCoinPromise = chooseCoins(db, contract.max_fee, contract.amount)
-    //    .then(x => generateDepositPermissions(db, x))
-    //    .then(executePayment);
+    let offer = detail.offer;
+    getPossibleMintCoins(db, offer.contract.amount, offer.contract.max_fee, offer.contract.mints)
+        .then((mcs) => {
+        if (Object.keys(mcs).length == 0) {
+            sendResponse({ error: "Not enough coins." });
+            return;
+        }
+        let mintUrl = Object.keys(mcs)[0];
+        let ds = signDeposit(db, offer, mcs[mintUrl]);
+        return executePay(db, offer, ds, detail.merchantPageUrl, mintUrl);
+    });
     return true;
 }
 function confirmReserve(db, detail, sendResponse) {
@@ -110,7 +218,10 @@ function confirmReserve(db, detail, sendResponse) {
                         sendResponse(resp);
                         var mint;
                         updateMintFromUrl(db, reserveRecord.mint_base_url)
-                            .then((m) => { mint = m; return updateReserve(db, reservePub, mint); })
+                            .then((m) => {
+                            mint = m;
+                            return updateReserve(db, reservePub, mint);
+                        })
                             .then((reserve) => depleteReserve(db, reserve, mint));
                     });
                     break;
@@ -213,7 +324,7 @@ function withdrawExecute(db, pc) {
                 console.log("Withdrawal successful");
                 console.log(myRequest.responseText);
                 let resp = JSON.parse(myRequest.responseText);
-                let denomSig = rsaUnblind(RsaSignature.fromCrock(resp.coin_ev), RsaBlindingKey.fromCrock(pc.blindingKey), RsaPublicKey.fromCrock(pc.denomPub));
+                let denomSig = rsaUnblind(RsaSignature.fromCrock(resp.ev_sig), RsaBlindingKey.fromCrock(pc.blindingKey), RsaPublicKey.fromCrock(pc.denomPub));
                 let coin = {
                     coinPub: pc.coinPub,
                     coinPriv: pc.coinPriv,
@@ -397,7 +508,9 @@ function dumpDb(db, detail, sendResponse) {
         let name = db.objectStoreNames[i];
         let storeDump = {};
         dump.stores[name] = storeDump;
-        let store = tx.objectStore(name).openCursor().addEventListener('success', (e) => {
+        let store = tx.objectStore(name)
+            .openCursor()
+            .addEventListener('success', (e) => {
             let cursor = e.target.result;
             if (cursor) {
                 storeDump[cursor.key] = cursor.value;
diff --git a/extension/background/wallet.ts b/extension/background/wallet.ts
index 07c8743e1..281a24c6e 100644
--- a/extension/background/wallet.ts
+++ b/extension/background/wallet.ts
@@ -2,39 +2,11 @@
 /// <reference path="../decl/chrome/chrome.d.ts" />
 'use strict';
 
-const DB_NAME = "taler";
-const DB_VERSION = 1;
 
-
-/**
- * Return a promise that resolves
- * to the taler wallet db.
- */
-function openTalerDb(): Promise<IDBDatabase> {
-  return new Promise((resolve, reject) => {
-    let req = indexedDB.open(DB_NAME, DB_VERSION);
-    req.onerror = (e) => {
-      reject(e);
-    };
-    req.onsuccess = (e) => {
-      resolve(req.result);
-    };
-    req.onupgradeneeded = (e) => {
-      let db = req.result;
-      console.log ("DB: upgrade needed: oldVersion = " + e.oldVersion);
-      switch (e.oldVersion) {
-        case 0: // DB does not exist yet
-          db.createObjectStore("mints", { keyPath: "baseUrl" });
-          db.createObjectStore("reserves", { keyPath: "reserve_pub"});
-          db.createObjectStore("denoms", { keyPath: "denomPub" });
-          let coins = db.createObjectStore("coins", { keyPath: "coinPub" });
-          coins.createIndex("mintBaseUrl", "mintBaseUrl");
-          db.createObjectStore("transactions", { keyPath: "contractHash" });
-          db.createObjectStore("precoins", { keyPath: "coinPub", autoIncrement: true });
-          break;
-      }
-    };
-  });
+interface AmountJson {
+  value: number;
+  fraction: number;
+  currency: string;
 }
 
 
@@ -52,38 +24,244 @@ function canonicalizeBaseUrl(url) {
   return x.href()
 }
 
+
 interface ConfirmPayRequest {
-  offer: any;
-  selectedMint: any;
+  merchantPageUrl: string;
+  offer: Offer;
+}
+
+interface MintCoins {
+  [mintUrl: string]: Db.CoinWithDenom[];
+}
+
+interface Offer {
+  contract: Contract;
+  sig: string;
+  H_contract: string;
+}
+
+interface Contract {
+  H_wire: string;
+  amount: AmountJson;
+  auditors: string[];
+  expiry: string,
+  locations: string[];
+  max_fee: AmountJson;
+  merchant: any;
+  merchant_pub: string;
+  mints: MintInfo[];
+  pay_url: string;
+  products: string[];
+  refund_deadline: string;
+  timestamp: string;
+  transaction_id: number;
+}
+
+
+interface CoinPaySig {
+  coin_sig: string;
+  coin_pub: string;
+  ub_sig: string;
+  denom_pub: string;
+  f: AmountJson;
+}
+
+
+type PayCoinInfo = Array<{ updatedCoin: Db.Coin, sig: CoinPaySig }>;
+
+
+function signDeposit(db: IDBDatabase,
+                     offer: Offer,
+                     cds: Db.CoinWithDenom[]): PayCoinInfo {
+  let ret = [];
+  let amountSpent = Amount.getZero(cds[0].coin.currentAmount.currency);
+  let amountRemaining = new Amount(offer.contract.amount);
+  cds = copy(cds);
+  for (let cd of cds) {
+    let coinSpend;
+    if (amountRemaining.cmp(new Amount(cd.coin.currentAmount)) < 0) {
+      coinSpend = new Amount(amountRemaining.toJson());
+    } else {
+      coinSpend = new Amount(cd.coin.currentAmount);
+    }
+
+    let d = new DepositRequestPS({
+      h_contract: HashCode.fromCrock(offer.H_contract),
+      h_wire: HashCode.fromCrock(offer.contract.H_wire),
+      amount_with_fee: new Amount(cd.coin.currentAmount).toNbo(),
+      coin_pub: EddsaPublicKey.fromCrock(cd.coin.coinPub),
+      deposit_fee: new Amount(cd.denom.fee_deposit).toNbo(),
+      merchant: EddsaPublicKey.fromCrock(offer.contract.merchant_pub),
+      refund_deadline: AbsoluteTimeNbo.fromTalerString(offer.contract.refund_deadline),
+      timestamp: AbsoluteTimeNbo.fromTalerString(offer.contract.timestamp),
+      transaction_id: UInt64.fromNumber(offer.contract.transaction_id),
+    });
+
+    amountSpent.add(coinSpend);
+
+    let newAmount = new Amount(cd.coin.currentAmount);
+    newAmount.sub(coinSpend);
+    cd.coin.currentAmount = newAmount.toJson();
+
+    let coinSig = eddsaSign(d.toPurpose(),
+                            EddsaPrivateKey.fromCrock(cd.coin.coinPriv))
+      .toCrock();
+
+    let s: CoinPaySig = {
+      coin_sig: coinSig,
+      coin_pub: cd.coin.coinPub,
+      ub_sig: cd.coin.denomSig,
+      denom_pub: cd.coin.denomPub,
+      f: amountSpent.toJson(),
+    };
+    ret.push({sig: coinSig, updatedCoin: cd.coin});
+  }
+  return ret;
+}
+
+interface MintInfo {
+  master_pub: string;
+  url: string;
+}
+
+
+/**
+ * Get mints and associated coins that are still spendable,
+ * but only if the sum the coins' remaining value exceeds the payment amount.
+ * @param db
+ * @param paymentAmount
+ * @param depositFeeLimit
+ * @param mintKeys
+ */
+function getPossibleMintCoins(db: IDBDatabase,
+                              paymentAmount: AmountJson,
+                              depositFeeLimit: AmountJson,
+                              allowedMints: MintInfo[]): Promise<MintCoins> {
+  return new Promise((resolve, reject) => {
+    let m: MintCoins = {};
+    let found = false;
+    let tx = db.transaction(["mints", "coins"]);
+    // First pass: Get all coins from acceptable mints.
+    for (let info of allowedMints) {
+      let req_mints = tx.objectStore("mints")
+                        .index("pubKey")
+                        .get(info.master_pub);
+      req_mints.onsuccess = (e) => {
+        let mint: Db.Mint = req_mints.result;
+        let req_coins = tx.objectStore("coins")
+                          .index("mintBaseUrl")
+                          .openCursor(IDBKeyRange.only(mint.baseUrl));
+        req_coins.onsuccess = (e) => {
+          let cursor: IDBCursorWithValue = req_coins.result;
+          if (!cursor) {
+            return;
+          }
+          let cd = {
+            coin: cursor.value,
+            denom: mint.keys.denoms[cursor.value.denomPub]
+          };
+          let x = m[mint.baseUrl];
+          if (!x) {
+            m[mint.baseUrl] = [cd];
+          } else {
+            x.push(cd);
+          }
+        }
+      }
+    }
+
+    tx.oncomplete = (e) => {
+      let ret: MintCoins = {};
+
+      nextMint:
+        for (let key in m) {
+          let coins = m[key].map((x) => ({
+            a: new Amount(x.denom.fee_deposit),
+            c: x
+          }));
+          // Sort by ascending deposit fee
+          coins.sort((o1, o2) => o1.a.cmp(o2.a));
+          let maxFee = new Amount(depositFeeLimit);
+          let minAmount = new Amount(paymentAmount);
+          let accFee = new Amount(coins[0].c.denom.fee_deposit);
+          let accAmount = new Amount(coins[0].c.coin.currentAmount);
+          for (let i = 0; i < coins.length; i++) {
+            if (accFee.cmp(maxFee) >= 0) {
+              continue nextMint;
+            }
+            if (accAmount.cmp(minAmount) >= 0) {
+              ret[key] = m[key];
+              continue nextMint;
+            }
+            accFee.add(coins[i].a);
+            accFee.add(new Amount(coins[i].c.coin.currentAmount));
+          }
+        }
+      resolve(ret);
+    };
+
+    tx.onerror = (e) => {
+      reject();
+    }
+  });
 }
 
 
-function grantCoins(db: IDBDatabase,
-                    feeThreshold: AmountJson,
-                    paymentAmount: AmountJson,
-                    mintBaseUrl: string): Promise<any> {
-  throw "not implemented";
+function executePay(db,
+                    offer: Offer,
+                    payCoinInfo: PayCoinInfo,
+                    merchantBaseUrl: string,
+                    chosenMint: string) {
+  return new Promise((resolve, reject) => {
+    let reqData = {};
+    reqData["H_wire"] = offer.contract.H_wire;
+    reqData["H_contract"] = offer.H_contract;
+    reqData["transaction_id"] = offer.contract.transaction_id;
+    reqData["refund_deadline"] = offer.contract.refund_deadline;
+    reqData["mint"] = chosenMint;
+    reqData["coins"] = payCoinInfo.map((x) => x.sig);
+    let payUrl = URI(merchantBaseUrl).absoluteTo(merchantBaseUrl);
+    console.log("Merchant URL", payUrl);
+    let req = new XMLHttpRequest();
+    req.open('post', payUrl.href());
+    req.setRequestHeader("Content-Type",
+                         "application/json;charset=UTF-8");
+    req.addEventListener('readystatechange', (e) => {
+      if (req.readyState == XMLHttpRequest.DONE) {
+        resolve()
+      }
+    });
+  });
 }
 
 
-function confirmPay(db, detail: ConfirmPayRequest, sendResponse) { 
+function confirmPay(db, detail: ConfirmPayRequest, sendResponse) {
   console.log("confirmPay", JSON.stringify(detail));
   let tx = db.transaction(['transactions'], 'readwrite');
   let trans = {
     contractHash: detail.offer.H_contract,
     contract: detail.offer.contract,
     sig: detail.offer
-  }
-
-  let contract = detail.offer.contract;
-
-  //let chosenCoinPromise = chooseCoins(db, contract.max_fee, contract.amount)
-  //    .then(x => generateDepositPermissions(db, x))
-  //    .then(executePayment);
+  };
 
+  let offer: Offer = detail.offer;
+  getPossibleMintCoins(db,
+                       offer.contract.amount,
+                       offer.contract.max_fee,
+                       offer.contract.mints)
+    .then((mcs) => {
+      if (Object.keys(mcs).length == 0) {
+        sendResponse({error: "Not enough coins."});
+        return;
+      }
+      let mintUrl = Object.keys(mcs)[0];
+      let ds = signDeposit(db, offer, mcs[mintUrl]);
+      return executePay(db, offer, ds, detail.merchantPageUrl, mintUrl);
+    });
   return true;
 }
 
+
 function confirmReserve(db, detail, sendResponse) {
   let reservePriv = EddsaPrivateKey.create();
   let reservePub = reservePriv.getPublicKey();
@@ -131,8 +309,11 @@ function confirmReserve(db, detail, sendResponse) {
             sendResponse(resp);
             var mint;
             updateMintFromUrl(db, reserveRecord.mint_base_url)
-                .then((m) => { mint = m; return updateReserve(db, reservePub, mint); })
-                .then((reserve) => depleteReserve(db, reserve, mint));
+              .then((m) => {
+                mint = m;
+                return updateReserve(db, reservePub, mint);
+              })
+              .then((reserve) => depleteReserve(db, reserve, mint));
           });
           break;
         default:
@@ -160,8 +341,8 @@ function rankDenom(denom1: any, denom2: any) {
 
 
 function withdrawPrepare(db: IDBDatabase,
-                         denom: Denomination,
-                         reserve): Promise<PreCoin> {
+                         denom: Db.Denomination,
+                         reserve): Promise<Db.PreCoin> {
   let reservePriv = new EddsaPrivateKey();
   reservePriv.loadCrock(reserve.reserve_priv);
   let reservePub = new EddsaPublicKey();
@@ -196,7 +377,7 @@ function withdrawPrepare(db: IDBDatabase,
 
   console.log("crypto done, doing request");
 
-  let preCoin: PreCoin = {
+  let preCoin: Db.PreCoin = {
     reservePub: reservePub.toCrock(),
     blindingKey: blindingFactor.toCrock(),
     coinPub: coinPub.toCrock(),
@@ -219,57 +400,59 @@ function withdrawPrepare(db: IDBDatabase,
   });
 }
 
+
 function dbGet(db, store: string, key: any): Promise<any> {
   let tx = db.transaction([store]);
   let req = tx.objectStore(store).get(key);
   return new Promise((resolve, reject) => {
-    req.onsuccess = (e) => resolve(req.result); 
+    req.onsuccess = (e) => resolve(req.result);
   });
 }
 
 
-function withdrawExecute(db, pc: PreCoin): Promise<Coin> {
+function withdrawExecute(db, pc: Db.PreCoin): Promise<Db.Coin> {
   return dbGet(db, 'reserves', pc.reservePub)
-      .then((r) => new Promise((resolve, reject) => {
-        console.log("loading precoin", JSON.stringify(pc));
-          let wd: any = {};
-          wd.denom_pub = pc.denomPub;
-          wd.reserve_pub = pc.reservePub;
-          wd.reserve_sig = pc.withdrawSig;
-          wd.coin_ev = pc.coinEv;
-          let reqUrl = URI("reserve/withdraw").absoluteTo(r.mint_base_url);
-          let myRequest = new XMLHttpRequest();
-          console.log("making request to " + reqUrl.href());
-          myRequest.open('post', reqUrl.href());
-          myRequest.setRequestHeader("Content-Type", "application/json;charset=UTF-8");
-          myRequest.send(JSON.stringify(wd));
-          myRequest.addEventListener('readystatechange', (e) => {
-            if (myRequest.readyState == XMLHttpRequest.DONE) {
-              if (myRequest.status != 200) {
-                console.log("Withdrawal failed, status ", myRequest.status);
-                reject();
-                return;
-              }
-              console.log("Withdrawal successful");
-              console.log(myRequest.responseText);
-              let resp = JSON.parse(myRequest.responseText);
-              let denomSig = rsaUnblind(RsaSignature.fromCrock(resp.coin_ev),
-                                          RsaBlindingKey.fromCrock(pc.blindingKey),
-                                          RsaPublicKey.fromCrock(pc.denomPub));
-              let coin: Coin = {
-                coinPub: pc.coinPub,
-                coinPriv: pc.coinPriv,
-                denomPub: pc.denomPub,
-                denomSig:  denomSig.encode().toCrock(),
-                currentAmount: pc.coinValue
-              }
-              console.log("unblinded coin");
-              resolve(coin);
-            } else {
-              console.log("ready state change to", myRequest.status);
-            }
-          });
-      }));
+    .then((r) => new Promise((resolve, reject) => {
+      console.log("loading precoin", JSON.stringify(pc));
+      let wd: any = {};
+      wd.denom_pub = pc.denomPub;
+      wd.reserve_pub = pc.reservePub;
+      wd.reserve_sig = pc.withdrawSig;
+      wd.coin_ev = pc.coinEv;
+      let reqUrl = URI("reserve/withdraw").absoluteTo(r.mint_base_url);
+      let myRequest = new XMLHttpRequest();
+      console.log("making request to " + reqUrl.href());
+      myRequest.open('post', reqUrl.href());
+      myRequest.setRequestHeader("Content-Type",
+                                 "application/json;charset=UTF-8");
+      myRequest.send(JSON.stringify(wd));
+      myRequest.addEventListener('readystatechange', (e) => {
+        if (myRequest.readyState == XMLHttpRequest.DONE) {
+          if (myRequest.status != 200) {
+            console.log("Withdrawal failed, status ", myRequest.status);
+            reject();
+            return;
+          }
+          console.log("Withdrawal successful");
+          console.log(myRequest.responseText);
+          let resp = JSON.parse(myRequest.responseText);
+          let denomSig = rsaUnblind(RsaSignature.fromCrock(resp.ev_sig),
+                                    RsaBlindingKey.fromCrock(pc.blindingKey),
+                                    RsaPublicKey.fromCrock(pc.denomPub));
+          let coin: Db.Coin = {
+            coinPub: pc.coinPub,
+            coinPriv: pc.coinPriv,
+            denomPub: pc.denomPub,
+            denomSig: denomSig.encode().toCrock(),
+            currentAmount: pc.coinValue
+          };
+          console.log("unblinded coin");
+          resolve(coin);
+        } else {
+          console.log("ready state change to", myRequest.status);
+        }
+      });
+    }));
 }
 
 
@@ -284,14 +467,14 @@ function updateBadge(db) {
       cursor.continue();
     } else {
       console.log("badge");
-      chrome.browserAction.setBadgeText({text: ""+n});
+      chrome.browserAction.setBadgeText({text: "" + n});
       chrome.browserAction.setBadgeBackgroundColor({color: "#0F0"});
     }
   }
 }
 
 
-function storeCoin(db, coin: Coin) {
+function storeCoin(db, coin: Db.Coin) {
   let tx = db.transaction(['coins', 'precoins'], 'readwrite');
   tx.objectStore('precoins').delete(coin.coinPub);
   tx.objectStore('coins').add(coin);
@@ -306,8 +489,8 @@ function storeCoin(db, coin: Coin) {
 
 function withdraw(db, denom, reserve): Promise<void> {
   return withdrawPrepare(db, denom, reserve)
-      .then((pc) => withdrawExecute(db, pc))
-      .then((c) => storeCoin(db, c));
+    .then((pc) => withdrawExecute(db, pc))
+    .then((c) => storeCoin(db, c));
 }
 
 
@@ -344,7 +527,7 @@ function depleteReserve(db, reserve, mint) {
     console.log("doing work");
     let d = workList.pop();
     withdraw(db, d, reserve)
-        .then(() => next());
+      .then(() => next());
   }
 
   next();
@@ -408,7 +591,7 @@ function updateMintFromUrl(db, baseUrl) {
             console.log("keys invalid");
             reject();
           } else {
-            let mint = {
+            let mint: Db.Mint = {
               baseUrl: baseUrl,
               keys: mintKeysJson
             };
@@ -419,7 +602,7 @@ function updateMintFromUrl(db, baseUrl) {
               let di = {
                 denomPub: d.denom_pub,
                 value: d.value
-              }
+              };
               tx.objectStore('denoms').put(di);
             }
             tx.oncomplete = (e) => {
@@ -446,19 +629,21 @@ function dumpDb(db, detail, sendResponse) {
   console.log("stores: " + JSON.stringify(db.objectStoreNames));
   let tx = db.transaction(db.objectStoreNames);
   tx.addEventListener('complete', (e) => {
-      sendResponse(dump);
+    sendResponse(dump);
   });
   for (let i = 0; i < db.objectStoreNames.length; i++) {
     let name = db.objectStoreNames[i];
     let storeDump = {};
     dump.stores[name] = storeDump;
-    let store = tx.objectStore(name).openCursor().addEventListener('success', (e) => {
-      let cursor = e.target.result;
-      if (cursor) {
-        storeDump[cursor.key] = cursor.value;
-        cursor.continue();
-      }
-    });
+    let store = tx.objectStore(name)
+                  .openCursor()
+                  .addEventListener('success', (e) => {
+                    let cursor = e.target.result;
+                    if (cursor) {
+                      storeDump[cursor.key] = cursor.value;
+                      cursor.continue();
+                    }
+                  });
   }
   return true;
 }
@@ -513,7 +698,7 @@ chrome.browserAction.setBadgeText({text: ""});
 openTalerDb().then((db) => {
   console.log("db loaded");
   chrome.runtime.onMessage.addListener(
-    function (req, sender, onresponse) {
+    function(req, sender, onresponse) {
       let dispatch = {
         "confirm-reserve": confirmReserve,
         "confirm-pay": confirmPay,
@@ -524,7 +709,9 @@ openTalerDb().then((db) => {
       if (req.type in dispatch) {
         return dispatch[req.type](db, req.detail, onresponse);
       }
-      console.error(format("Request type {1} unknown, req {0}", JSON.stringify(req), req.type));
+      console.error(format("Request type {1} unknown, req {0}",
+                           JSON.stringify(req),
+                           req.type));
       return false;
     });
 });
diff --git a/extension/lib/util.js b/extension/lib/util.js
index 801d7d189..71bfce4d3 100644
--- a/extension/lib/util.js
+++ b/extension/lib/util.js
@@ -28,3 +28,7 @@ function format(s, ...args) {
     s = s.replace(/{([0-9]+)}/g, r);
     return s;
 }
+function promiseFinally(p, fn) {
+    return p.then((x) => { fn(); return x; })
+        .catch((e) => { fn(); throw e; });
+}
diff --git a/extension/lib/util.ts b/extension/lib/util.ts
index 106e22970..b30d60432 100644
--- a/extension/lib/util.ts
+++ b/extension/lib/util.ts
@@ -32,3 +32,8 @@ function format(s: string, ...args: any[]) {
   return s;
 }
 
+
+function promiseFinally<T>(p: Promise<T>, fn): Promise<T> {
+  return p.then((x) => { fn(); return x; })
+          .catch((e) => {fn(); throw e;});
+}
\ No newline at end of file
diff --git a/extension/pages/confirm-contract.html b/extension/pages/confirm-contract.html
index 8d68511dd..9959bb489 100644
--- a/extension/pages/confirm-contract.html
+++ b/extension/pages/confirm-contract.html
@@ -26,6 +26,10 @@
       <p />
     </script>
 
+    <script id="error-template" type="text/x-handlebars-template">
+      Payment was not successful: {{error}}
+    </script>
+
 
   </head>
   <body>
@@ -33,7 +37,9 @@
 
     <div id="render-contract"></div>
 
-    <button id="confirm-purchase">Confirm Purchase!</button>
+    <button id="confirm-pay">Confirm Pay!</button>
+
+    <div id="status"></div>
     
   </body>
 </html>
diff --git a/extension/pages/confirm-contract.js b/extension/pages/confirm-contract.js
index c59ac90a9..0f6d83744 100644
--- a/extension/pages/confirm-contract.js
+++ b/extension/pages/confirm-contract.js
@@ -23,16 +23,16 @@ document.addEventListener("DOMContentLoaded", (e) => {
     let html = template(offer.contract);
     $_("render-contract").innerHTML = html;
     document.getElementById("confirm-pay").addEventListener("click", (e) => {
-        let d = clone(query);
+        let d = {
+            offer: JSON.parse(query.offer)
+        };
         chrome.runtime.sendMessage({ type: 'confirm-pay', detail: d }, (resp) => {
-            if (resp.success === true) {
-                document.location.href = resp.backlink;
-            }
-            else {
-                document.body.innerHTML =
-                    `Oops, something went wrong.
-           Here is some more info:
-           <pre>${resp.text}</pre>`;
+            console.log("got response", resp);
+            if ("error" in resp) {
+                let source = $_("error-template").innerHTML;
+                let template = Handlebars.compile(source);
+                $_("status").innerHTML = template(resp);
+                return;
             }
         });
     });
diff --git a/extension/pages/confirm-contract.tsx b/extension/pages/confirm-contract.tsx
index 811e2e001..c9d41a2c8 100644
--- a/extension/pages/confirm-contract.tsx
+++ b/extension/pages/confirm-contract.tsx
@@ -34,15 +34,16 @@ document.addEventListener("DOMContentLoaded", (e) => {
   $_("render-contract").innerHTML = html;
 
   document.getElementById("confirm-pay").addEventListener("click", (e) => {
-    let d = clone(query);
+    let d = {
+      offer: JSON.parse(query.offer)
+    };
     chrome.runtime.sendMessage({type:'confirm-pay', detail: d}, (resp) => {
-      if (resp.success === true) {
-        document.location.href = resp.backlink;
-      } else {
-        document.body.innerHTML =
-          `Oops, something went wrong.
-           Here is some more info:
-           <pre>${resp.text}</pre>`;
+      console.log("got response", resp);
+      if ("error" in resp) {
+        let source = $_("error-template").innerHTML;
+        let template = Handlebars.compile(source);
+        $_("status").innerHTML = template(resp);
+        return;
       }
     });
   });
diff --git a/extension/pages/debug.html b/extension/pages/debug.html
index 7dfa7a9cc..24682dd24 100644
--- a/extension/pages/debug.html
+++ b/extension/pages/debug.html
@@ -7,5 +7,6 @@
     <h1>Debug Pages</h1>
     <a href="show-db.html">Show DB</a> <br>
     <a href="../popup/balance-overview.html">Show balance</a>
+
   </body>
 </html>
diff --git a/extension/popup/balance-overview.js b/extension/popup/balance-overview.js
index 4fd991b23..b2c5e0837 100644
--- a/extension/popup/balance-overview.js
+++ b/extension/popup/balance-overview.js
@@ -20,6 +20,15 @@ document.addEventListener('DOMContentLoaded', (e) => {
         let context = document.getElementById("balance-template").innerHTML;
         let template = Handlebars.compile(context);
         document.getElementById("content").innerHTML = template(wallet);
+        let el = document.getElementById("link-kudos");
+        if (el) {
+            el.onclick = (e) => {
+                let target = e.target;
+                chrome.tabs.create({
+                    "url": target.href
+                });
+            };
+        }
     });
     document.getElementById("debug").addEventListener("click", (e) => {
         chrome.tabs.create({
@@ -29,10 +38,4 @@ document.addEventListener('DOMContentLoaded', (e) => {
     document.getElementById("reset").addEventListener("click", (e) => {
         chrome.runtime.sendMessage({ type: "reset" });
     });
-    document.getElementById("link-kudos").addEventListener("click", (e) => {
-        let target = e.target;
-        chrome.tabs.create({
-            "url": target.href
-        });
-    });
 });
diff --git a/extension/popup/balance-overview.tsx b/extension/popup/balance-overview.tsx
index 88ff1bccb..38be50375 100644
--- a/extension/popup/balance-overview.tsx
+++ b/extension/popup/balance-overview.tsx
@@ -16,12 +16,22 @@ let React = {
   }
 }
 
+
 document.addEventListener('DOMContentLoaded', (e) => {
   console.log("content loaded");
   chrome.runtime.sendMessage({type: "balances"}, function(wallet) {
     let context = document.getElementById("balance-template").innerHTML;
     let template = Handlebars.compile(context);
     document.getElementById("content").innerHTML = template(wallet);
+    let el = document.getElementById("link-kudos");
+    if (el) {
+      el.onclick = (e) => {
+        let target: any = e.target;
+        chrome.tabs.create({
+          "url": target.href
+        }); 
+      };
+    }
   });
 
   document.getElementById("debug").addEventListener("click", (e) => {
@@ -32,10 +42,4 @@ document.addEventListener('DOMContentLoaded', (e) => {
   document.getElementById("reset").addEventListener("click", (e) => {
     chrome.runtime.sendMessage({type: "reset"});
   });
-  document.getElementById("link-kudos").addEventListener("click", (e) => {
-    let target: any = e.target;
-    chrome.tabs.create({
-      "url": target.href
-    }); 
-  });
 });