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// Copyright (c) 2009-2012 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 __CRYPTER_H__
#define __CRYPTER_H__
#include "allocators.h" /* for SecureString */
#include "key.h"
#include "serialize.h"
const unsigned int WALLET_CRYPTO_KEY_SIZE = 32;
const unsigned int WALLET_CRYPTO_SALT_SIZE = 8;
/*
Private key encryption is done based on a CMasterKey,
which holds a salt and random encryption key.
CMasterKeys are encrypted using AES-256-CBC using a key
derived using derivation method nDerivationMethod
(0 == EVP_sha512()) and derivation iterations nDeriveIterations.
vchOtherDerivationParameters is provided for alternative algorithms
which may require more parameters (such as scrypt).
Wallet Private Keys are then encrypted using AES-256-CBC
with the double-sha256 of the public key as the IV, and the
master key's key as the encryption key (see keystore.[ch]).
*/
/** Master key for wallet encryption */
class CMasterKey
{
public:
std::vector<unsigned char> vchCryptedKey;
std::vector<unsigned char> vchSalt;
// 0 = EVP_sha512()
// 1 = scrypt()
unsigned int nDerivationMethod;
unsigned int nDeriveIterations;
// Use this for more parameters to key derivation,
// such as the various parameters to scrypt
std::vector<unsigned char> vchOtherDerivationParameters;
IMPLEMENT_SERIALIZE
(
READWRITE(vchCryptedKey);
READWRITE(vchSalt);
READWRITE(nDerivationMethod);
READWRITE(nDeriveIterations);
READWRITE(vchOtherDerivationParameters);
)
CMasterKey()
{
// 25000 rounds is just under 0.1 seconds on a 1.86 GHz Pentium M
// ie slightly lower than the lowest hardware we need bother supporting
nDeriveIterations = 25000;
nDerivationMethod = 0;
vchOtherDerivationParameters = std::vector<unsigned char>(0);
}
};
typedef std::vector<unsigned char, secure_allocator<unsigned char> > CKeyingMaterial;
/** Encryption/decryption context with key information */
class CCrypter
{
private:
unsigned char chKey[WALLET_CRYPTO_KEY_SIZE];
unsigned char chIV[WALLET_CRYPTO_KEY_SIZE];
bool fKeySet;
public:
bool SetKeyFromPassphrase(const SecureString &strKeyData, const std::vector<unsigned char>& chSalt, const unsigned int nRounds, const unsigned int nDerivationMethod);
bool Encrypt(const CKeyingMaterial& vchPlaintext, std::vector<unsigned char> &vchCiphertext);
bool Decrypt(const std::vector<unsigned char>& vchCiphertext, CKeyingMaterial& vchPlaintext);
bool SetKey(const CKeyingMaterial& chNewKey, const std::vector<unsigned char>& chNewIV);
void CleanKey()
{
OPENSSL_cleanse(chKey, sizeof(chKey));
OPENSSL_cleanse(chIV, sizeof(chIV));
fKeySet = false;
}
CCrypter()
{
fKeySet = false;
// Try to keep the key data out of swap (and be a bit over-careful to keep the IV that we don't even use out of swap)
// Note that this does nothing about suspend-to-disk (which will put all our key data on disk)
// Note as well that at no point in this program is any attempt made to prevent stealing of keys by reading the memory of the running process.
LockedPageManager::Instance().LockRange(&chKey[0], sizeof chKey);
LockedPageManager::Instance().LockRange(&chIV[0], sizeof chIV);
}
~CCrypter()
{
CleanKey();
LockedPageManager::Instance().UnlockRange(&chKey[0], sizeof chKey);
LockedPageManager::Instance().UnlockRange(&chIV[0], sizeof chIV);
}
};
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);
#endif
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