crypter: fix the stored initialization vector size

AES IV's are 16bytes, not 32. This was harmless but confusing.

Add WALLET_CRYPTO_IV_SIZE to make its usage explicit.

src/wallet/crypter.cpp

@@ -37,7 +37,7 @@ bool CCrypter::SetKeyFromPassphrase(const SecureString& strKeyData, const std::v
 
 bool CCrypter::SetKey(const CKeyingMaterial& chNewKey, const std::vector<unsigned char>& chNewIV)
 {
-    if (chNewKey.size() != WALLET_CRYPTO_KEY_SIZE || chNewIV.size() != WALLET_CRYPTO_KEY_SIZE)
+    if (chNewKey.size() != WALLET_CRYPTO_KEY_SIZE || chNewIV.size() != WALLET_CRYPTO_IV_SIZE)
         return false;
 
     memcpy(&chKey[0], &chNewKey[0], sizeof chKey);
@@ -105,8 +105,8 @@ bool CCrypter::Decrypt(const std::vector<unsigned char>& vchCiphertext, CKeyingM
 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);
-    memcpy(&chIV[0], &nIV, WALLET_CRYPTO_KEY_SIZE);
+    std::vector<unsigned char> chIV(WALLET_CRYPTO_IV_SIZE);
+    memcpy(&chIV[0], &nIV, WALLET_CRYPTO_IV_SIZE);
     if(!cKeyCrypter.SetKey(vMasterKey, chIV))
         return false;
     return cKeyCrypter.Encrypt(*((const CKeyingMaterial*)&vchPlaintext), vchCiphertext);
@@ -115,8 +115,8 @@ static bool EncryptSecret(const CKeyingMaterial& vMasterKey, const CKeyingMateri
 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);
-    memcpy(&chIV[0], &nIV, WALLET_CRYPTO_KEY_SIZE);
+    std::vector<unsigned char> chIV(WALLET_CRYPTO_IV_SIZE);
+    memcpy(&chIV[0], &nIV, WALLET_CRYPTO_IV_SIZE);
     if(!cKeyCrypter.SetKey(vMasterKey, chIV))
         return false;
     return cKeyCrypter.Decrypt(vchCiphertext, *((CKeyingMaterial*)&vchPlaintext));

src/wallet/crypter.h

@@ -13,6 +13,7 @@ class uint256;
 
 const unsigned int WALLET_CRYPTO_KEY_SIZE = 32;
 const unsigned int WALLET_CRYPTO_SALT_SIZE = 8;
+const unsigned int WALLET_CRYPTO_IV_SIZE = 16;
 
 /**
  * Private key encryption is done based on a CMasterKey,
@@ -71,7 +72,7 @@ class CCrypter
 {
 private:
     unsigned char chKey[WALLET_CRYPTO_KEY_SIZE];
-    unsigned char chIV[WALLET_CRYPTO_KEY_SIZE];
+    unsigned char chIV[WALLET_CRYPTO_IV_SIZE];
     bool fKeySet;
 
 public: