Clean up wallet encryption code.

Add a new method DecryptKey in crypter.cpp, that combines the logic for
decrypting, initialising and validating a CKey object.  This was
previously duplicated.

src/crypter.cpp

@@ -102,7 +102,7 @@ bool CCrypter::Decrypt(const std::vector<unsigned char>& vchCiphertext, CKeyingM
 }
 
 
-bool EncryptSecret(const CKeyingMaterial& vMasterKey, const CKeyingMaterial &vchPlaintext, const uint256& nIV, std::vector<unsigned char> &vchCiphertext)
+static bool EncryptSecret(const CKeyingMaterial& vMasterKey, const CKeyingMaterial &vchPlaintext, const uint256& nIV, std::vector<unsigned char> &vchCiphertext)
 {
     CCrypter cKeyCrypter;
     std::vector<unsigned char> chIV(WALLET_CRYPTO_KEY_SIZE);
@@ -112,7 +112,7 @@ bool EncryptSecret(const CKeyingMaterial& vMasterKey, const CKeyingMaterial &vch
     return cKeyCrypter.Encrypt(*((const CKeyingMaterial*)&vchPlaintext), vchCiphertext);
 }
 
-bool DecryptSecret(const CKeyingMaterial& vMasterKey, const std::vector<unsigned char>& vchCiphertext, const uint256& nIV, CKeyingMaterial& vchPlaintext)
+static bool DecryptSecret(const CKeyingMaterial& vMasterKey, const std::vector<unsigned char>& vchCiphertext, const uint256& nIV, CKeyingMaterial& vchPlaintext)
 {
     CCrypter cKeyCrypter;
     std::vector<unsigned char> chIV(WALLET_CRYPTO_KEY_SIZE);
@@ -122,6 +122,19 @@ bool DecryptSecret(const CKeyingMaterial& vMasterKey, const std::vector<unsigned
     return cKeyCrypter.Decrypt(vchCiphertext, *((CKeyingMaterial*)&vchPlaintext));
 }
 
+static bool DecryptKey(const CKeyingMaterial& vMasterKey, const std::vector<unsigned char>& vchCryptedSecret, const CPubKey& vchPubKey, CKey& key)
+{
+    CKeyingMaterial vchSecret;
+    if(!DecryptSecret(vMasterKey, vchCryptedSecret, vchPubKey.GetHash(), vchSecret))
+        return false;
+
+    if (vchSecret.size() != 32)
+        return false;
+
+    key.Set(vchSecret.begin(), vchSecret.end(), vchPubKey.IsCompressed());
+    return key.VerifyPubKey(vchPubKey);
+}
+
 bool CCryptoKeyStore::SetCrypted()
 {
     LOCK(cs_KeyStore);
@@ -161,20 +174,8 @@ bool CCryptoKeyStore::Unlock(const CKeyingMaterial& vMasterKeyIn)
         {
             const CPubKey &vchPubKey = (*mi).second.first;
             const std::vector<unsigned char> &vchCryptedSecret = (*mi).second.second;
-            CKeyingMaterial vchSecret;
-            if(!DecryptSecret(vMasterKeyIn, vchCryptedSecret, vchPubKey.GetHash(), vchSecret))
-            {
-                keyFail = true;
-                break;
-            }
-            if (vchSecret.size() != 32)
-            {
-                keyFail = true;
-                break;
-            }
             CKey key;
-            key.Set(vchSecret.begin(), vchSecret.end(), vchPubKey.IsCompressed());
-            if (key.GetPubKey() != vchPubKey)
+            if (!DecryptKey(vMasterKeyIn, vchCryptedSecret, vchPubKey, key))
             {
                 keyFail = true;
                 break;
@@ -243,13 +244,7 @@ bool CCryptoKeyStore::GetKey(const CKeyID &address, CKey& keyOut) const
         {
             const CPubKey &vchPubKey = (*mi).second.first;
             const std::vector<unsigned char> &vchCryptedSecret = (*mi).second.second;
-            CKeyingMaterial vchSecret;
-            if (!DecryptSecret(vMasterKey, vchCryptedSecret, vchPubKey.GetHash(), vchSecret))
-                return false;
-            if (vchSecret.size() != 32)
-                return false;
-            keyOut.Set(vchSecret.begin(), vchSecret.end(), vchPubKey.IsCompressed());
-            return true;
+            return DecryptKey(vMasterKey, vchCryptedSecret, vchPubKey, keyOut);
         }
     }
     return false;

src/crypter.h

@@ -107,9 +107,6 @@ public:
     }
 };
 
-bool EncryptSecret(const CKeyingMaterial& vMasterKey, const CKeyingMaterial &vchPlaintext, const uint256& nIV, std::vector<unsigned char> &vchCiphertext);
-bool DecryptSecret(const CKeyingMaterial& vMasterKey, const std::vector<unsigned char>& vchCiphertext, const uint256& nIV, CKeyingMaterial& vchPlaintext);
-
 /** Keystore which keeps the private keys encrypted.
  * It derives from the basic key store, which is used if no encryption is active.
  */