CSecret/CKey -> CKey/CPubKey split/refactor

1 files changed, 131 insertions, 92 deletions

diff --git a/src/key.h b/src/key.h
index 1b122112f3..b9ecd48570 100644
--- a/src/key.h
+++ b/src/key.h
@@ -1,11 +1,10 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
-// Copyright (c) 2009-2012 The Bitcoin developers
+// Copyright (c) 2009-2013 The Bitcoin developers
 // Distributed under the MIT/X11 software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 #ifndef BITCOIN_KEY_H
 #define BITCOIN_KEY_H
 
-#include <stdexcept>
 #include <vector>
 
 #include "allocators.h"
@@ -13,23 +12,6 @@
 #include "uint256.h"
 #include "hash.h"
 
-#include <openssl/ec.h> // for EC_KEY definition
-
-// secp160k1
-// const unsigned int PRIVATE_KEY_SIZE = 192;
-// const unsigned int PUBLIC_KEY_SIZE  = 41;
-// const unsigned int SIGNATURE_SIZE   = 48;
-//
-// secp192k1
-// const unsigned int PRIVATE_KEY_SIZE = 222;
-// const unsigned int PUBLIC_KEY_SIZE  = 49;
-// const unsigned int SIGNATURE_SIZE   = 57;
-//
-// secp224k1
-// const unsigned int PRIVATE_KEY_SIZE = 250;
-// const unsigned int PUBLIC_KEY_SIZE  = 57;
-// const unsigned int SIGNATURE_SIZE   = 66;
-//
 // secp256k1:
 // const unsigned int PRIVATE_KEY_SIZE = 279;
 // const unsigned int PUBLIC_KEY_SIZE  = 65;
@@ -38,12 +20,6 @@
 // see www.keylength.com
 // script supports up to 75 for single byte push
 
-class key_error : public std::runtime_error
-{
-public:
-    explicit key_error(const std::string& str) : std::runtime_error(str) {}
-};
-
 /** A reference to a CKey: the Hash160 of its serialized public key */
 class CKeyID : public uint160
 {
@@ -63,8 +39,11 @@ public:
 /** An encapsulated public key. */
 class CPubKey {
 private:
+    // Just store the serialized data.
+    // Its length can very cheaply be computed from the first byte.
     unsigned char vch[65];
 
+    // Compute the length of a pubkey with a given first byte.
     unsigned int static GetLen(unsigned char chHeader) {
         if (chHeader == 2 || chHeader == 3)
             return 33;
@@ -73,146 +52,206 @@ private:
         return 0;
     }
 
-    unsigned char *begin() {
-        return vch;
+    // Set this key data to be invalid
+    void Invalidate() {
+        vch[0] = 0xFF;
     }
 
-    friend class CKey;
-
 public:
-    CPubKey() { vch[0] = 0xFF; }
-
-    CPubKey(const std::vector<unsigned char> &vchPubKeyIn) {
-        int len = vchPubKeyIn.empty() ? 0 : GetLen(vchPubKeyIn[0]);
-        if (len) {
-            memcpy(vch, &vchPubKeyIn[0], len);
-        } else {
-            vch[0] = 0xFF;
-        }
+    // Construct an invalid public key.
+    CPubKey() {
+        Invalidate();
     }
 
-    unsigned int size() const {
-        return GetLen(vch[0]);
+    // Initialize a public key using begin/end iterators to byte data.
+    template<typename T>
+    void Set(const T pbegin, const T pend) {
+        int len = pend == pbegin ? 0 : GetLen(pbegin[0]);
+        if (len && len == (pend-pbegin))
+            memcpy(vch, (unsigned char*)&pbegin[0], len);
+        else
+            Invalidate();
     }
 
-    const unsigned char *begin() const {
-        return vch;
+    // Construct a public key using begin/end iterators to byte data.
+    template<typename T>
+    CPubKey(const T pbegin, const T pend) {
+        Set(pbegin, pend);
     }
 
-    const unsigned char *end() const {
-        return vch+size();
+    // Construct a public key from a byte vector.
+    CPubKey(const std::vector<unsigned char> &vch) {
+        Set(vch.begin(), vch.end());
     }
 
-    friend bool operator==(const CPubKey &a, const CPubKey &b) { return memcmp(a.vch, b.vch, a.size()) == 0; }
-    friend bool operator!=(const CPubKey &a, const CPubKey &b) { return memcmp(a.vch, b.vch, a.size()) != 0; }
+    // Simply read-only vector-like interface to the pubkey data.
+    unsigned int size() const { return GetLen(vch[0]); }
+    const unsigned char *begin() const { return vch; }
+    const unsigned char *end() const { return vch+size(); }
+    const unsigned char &operator[](unsigned int pos) const { return vch[pos]; }
+
+    // Comparator implementation.
+    friend bool operator==(const CPubKey &a, const CPubKey &b) {
+        return a.vch[0] == b.vch[0] &&
+               memcmp(a.vch, b.vch, a.size()) == 0;
+    }
+    friend bool operator!=(const CPubKey &a, const CPubKey &b) {
+        return !(a == b);
+    }
     friend bool operator<(const CPubKey &a, const CPubKey &b) {
         return a.vch[0] < b.vch[0] ||
-               (a.vch[0] == b.vch[0] && memcmp(a.vch+1, b.vch+1, a.size() - 1) < 0);
+               (a.vch[0] == b.vch[0] && memcmp(a.vch, b.vch, a.size()) < 0);
     }
 
+    // Implement serialization, as if this was a byte vector.
     unsigned int GetSerializeSize(int nType, int nVersion) const {
         return size() + 1;
     }
-
     template<typename Stream> void Serialize(Stream &s, int nType, int nVersion) const {
         unsigned int len = size();
         ::Serialize(s, VARINT(len), nType, nVersion);
         s.write((char*)vch, len);
     }
-
     template<typename Stream> void Unserialize(Stream &s, int nType, int nVersion) {
         unsigned int len;
         ::Unserialize(s, VARINT(len), nType, nVersion);
         if (len <= 65) {
             s.read((char*)vch, len);
         } else {
-            // invalid pubkey
-            vch[0] = 0xFF;
+            // invalid pubkey, skip available data
             char dummy;
             while (len--)
                 s.read(&dummy, 1);
+            Invalidate();
         }
     }
 
+    // Get the KeyID of this public key (hash of its serialization)
     CKeyID GetID() const {
         return CKeyID(Hash160(vch, vch+size()));
     }
 
+    // Get the 256-bit hash of this public key.
     uint256 GetHash() const {
         return Hash(vch, vch+size());
     }
 
+    // just check syntactic correctness.
     bool IsValid() const {
         return size() > 0;
     }
 
+    // fully validate whether this is a valid public key (more expensive than IsValid())
+    bool IsFullyValid() const;
+
+    // Check whether this is a compressed public key.
     bool IsCompressed() const {
         return size() == 33;
     }
 
-    std::vector<unsigned char> Raw() const {
-        return std::vector<unsigned char>(vch, vch+size());
-    }
+    // Verify a DER signature (~72 bytes).
+    // If this public key is not fully valid, the return value will be false.
+    bool Verify(const uint256 &hash, const std::vector<unsigned char>& vchSig) const;
+
+    // Verify a compact signature (~65 bytes).
+    // See CKey::SignCompact.
+    bool VerifyCompact(const uint256 &hash, const std::vector<unsigned char>& vchSig) const;
+
+    // Recover a public key from a compact signature.
+    bool RecoverCompact(const uint256 &hash, const std::vector<unsigned char>& vchSig);
+
+    // Turn this public key into an uncompressed public key.
+    bool Decompress();
 };
 
 
 // secure_allocator is defined in allocators.h
 // CPrivKey is a serialized private key, with all parameters included (279 bytes)
 typedef std::vector<unsigned char, secure_allocator<unsigned char> > CPrivKey;
-// CSecret is a serialization of just the secret parameter (32 bytes)
-typedef std::vector<unsigned char, secure_allocator<unsigned char> > CSecret;
 
-/** An encapsulated OpenSSL Elliptic Curve key (public and/or private) */
-class CKey
-{
-protected:
-    EC_KEY* pkey;
-    bool fSet;
-    bool fCompressedPubKey;
+/** An encapsulated private key. */
+class CKey {
+private:
+    // Whether this private key is valid. We check for correctness when modifying the key
+    // data, so fValid should always correspond to the actual state.
+    bool fValid;
 
+    // Whether the public key corresponding to this private key is (to be) compressed.
+    bool fCompressed;
+
+    // The actual byte data
+    unsigned char vch[32];
+
+    // Check whether the 32-byte array pointed to be vch is valid keydata.
+    bool static Check(const unsigned char *vch);
 public:
-    void SetCompressedPubKey(bool fCompressed = true);
 
-    void Reset();
+    // Construct an invalid private key.
+    CKey() : fValid(false) {
+        LockObject(vch);
+    }
 
-    CKey();
-    CKey(const CKey& b);
+    // Copy constructor. This is necessary because of memlocking.
+    CKey(const CKey &secret) : fValid(secret.fValid), fCompressed(secret.fCompressed) {
+        LockObject(vch);
+        memcpy(vch, secret.vch, sizeof(vch));
+    }
 
-    CKey& operator=(const CKey& b);
+    // Destructor (again necessary because of memlocking).
+    ~CKey() {
+        UnlockObject(vch);
+    }
 
-    ~CKey();
+    // Initialize using begin and end iterators to byte data.
+    template<typename T>
+    void Set(const T pbegin, const T pend, bool fCompressedIn) {
+        if (pend - pbegin != 32) {
+            fValid = false;
+            return;
+        }
+        if (Check(&pbegin[0])) {
+            memcpy(vch, (unsigned char*)&pbegin[0], 32);
+            fValid = true;
+            fCompressed = fCompressedIn;
+        } else {
+            fValid = false;
+        }
+    }
+
+    // Simple read-only vector-like interface.
+    unsigned int size() const { return (fValid ? 32 : 0); }
+    const unsigned char *begin() const { return vch; }
+    const unsigned char *end() const { return vch + size(); }
+
+    // Check whether this private key is valid.
+    bool IsValid() const { return fValid; }
 
-    bool IsNull() const;
-    bool IsCompressed() const;
+    // Check whether the public key corresponding to this private key is (to be) compressed.
+    bool IsCompressed() const { return fCompressed; }
 
+    // Initialize from a CPrivKey (serialized OpenSSL private key data).
+    bool SetPrivKey(const CPrivKey &vchPrivKey, bool fCompressed);
+
+    // Generate a new private key using a cryptographic PRNG.
     void MakeNewKey(bool fCompressed);
-    bool SetPrivKey(const CPrivKey& vchPrivKey);
-    bool SetSecret(const CSecret& vchSecret, bool fCompressed = false);
-    CSecret GetSecret(bool &fCompressed) const;
+
+    // Convert the private key to a CPrivKey (serialized OpenSSL private key data).
+    // This is expensive.
     CPrivKey GetPrivKey() const;
-    bool SetPubKey(const CPubKey& vchPubKey);
+
+    // Compute the public key from a private key.
+    // This is expensive.
     CPubKey GetPubKey() const;
 
-    bool Sign(uint256 hash, std::vector<unsigned char>& vchSig);
+    // Create a DER-serialized signature.
+    bool Sign(const uint256 &hash, std::vector<unsigned char>& vchSig) const;
 
-    // create a compact signature (65 bytes), which allows reconstructing the used public key
+    // Create a compact signature (65 bytes), which allows reconstructing the used public key.
     // The format is one header byte, followed by two times 32 bytes for the serialized r and s values.
     // The header byte: 0x1B = first key with even y, 0x1C = first key with odd y,
-    //                  0x1D = second key with even y, 0x1E = second key with odd y
-    bool SignCompact(uint256 hash, std::vector<unsigned char>& vchSig);
-
-    // reconstruct public key from a compact signature
-    // This is only slightly more CPU intensive than just verifying it.
-    // If this function succeeds, the recovered public key is guaranteed to be valid
-    // (the signature is a valid signature of the given data for that key)
-    bool SetCompactSignature(uint256 hash, const std::vector<unsigned char>& vchSig);
-
-    bool Verify(uint256 hash, const std::vector<unsigned char>& vchSig);
-
-    // Verify a compact signature
-    bool VerifyCompact(uint256 hash, const std::vector<unsigned char>& vchSig);
-
-    bool IsValid();
+    //                  0x1D = second key with even y, 0x1E = second key with odd y,
+    //                  add 0x04 for compressed keys.
+    bool SignCompact(const uint256 &hash, std::vector<unsigned char>& vchSig) const;
 };
 
 #endif