From 97447f981fb9e2b0c4c0c8c095464c4dbd91da29 Mon Sep 17 00:00:00 2001
From: Jonathan Underwood <junderwood@bitcoinbank.co.jp>
Date: Wed, 10 Jul 2019 08:30:23 +0900
Subject: BIP174: Include suggested sighash check

---
 bip-0174.mediawiki | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

(limited to 'bip-0174.mediawiki')

diff --git a/bip-0174.mediawiki b/bip-0174.mediawiki
index f197728..b352c3b 100644
--- a/bip-0174.mediawiki
+++ b/bip-0174.mediawiki
@@ -319,6 +319,8 @@ For a Signer to only produce valid signatures for what it expects to sign, it mu
 * If a witness UTXO is provided, no non-witness signature may be created
 * If a redeemScript is provided, the scriptPubKey must be for that redeemScript
 * If a witnessScript is provided, the scriptPubKey or the redeemScript must be for that witnessScript
+* If a sighash type is provided, the signer must check that the sighash is acceptable. If unacceptable, they must fail.
+* If a sighash type is not provided, the signer should sign using SIGHASH_ALL, but may use any sighash type they wish.
 
 =====Simple Signer Algorithm=====
 
@@ -326,13 +328,17 @@ A simple signer can use the following algorithm to determine what and how to sig
 
 <pre>
 sign_witness(script_code, i):
-    for key in psbt.inputs[i].keys:
-        if IsMine(key):
+    for key, sighash_type in psbt.inputs[i].items:
+        if sighash_type == None:
+            sighash_type = SIGHASH_ALL
+        if IsMine(key) and IsAcceptable(sighash_type):
             sign(witness_sighash(script_code, i, input))
 
 sign_non_witness(script_code, i):
-    for key in psbt.inputs[i].keys:
-        if IsMine(key):
+    for key, sighash_type in psbt.inputs[i].items:
+        if sighash_type == None:
+            sighash_type = SIGHASH_ALL
+        if IsMine(key) and IsAcceptable(sighash_type):
             sign(non_witness_sighash(script_code, i, input))
 
 for input,i in enumerate(psbt.inputs):
-- 
cgit v1.2.3

