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// Copyright (c) 2009-2016 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#ifndef BITCOIN_WALLET_CRYPTER_H
#define BITCOIN_WALLET_CRYPTER_H
#include "keystore.h"
#include "serialize.h"
#include "support/allocators/secure.h"
#include <atomic>
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,
* 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;
ADD_SERIALIZE_METHODS;
template <typename Stream, typename Operation>
inline void SerializationOp(Stream& s, Operation ser_action) {
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;
namespace wallet_crypto
{
class TestCrypter;
}
/** Encryption/decryption context with key information */
class CCrypter
{
friend class wallet_crypto::TestCrypter; // for test access to chKey/chIV
private:
std::vector<unsigned char, secure_allocator<unsigned char>> vchKey;
std::vector<unsigned char, secure_allocator<unsigned char>> vchIV;
bool fKeySet;
int BytesToKeySHA512AES(const std::vector<unsigned char>& chSalt, const SecureString& strKeyData, int count, unsigned char *key,unsigned char *iv) const;
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) const;
bool Decrypt(const std::vector<unsigned char>& vchCiphertext, CKeyingMaterial& vchPlaintext) const;
bool SetKey(const CKeyingMaterial& chNewKey, const std::vector<unsigned char>& chNewIV);
void CleanKey()
{
memory_cleanse(vchKey.data(), vchKey.size());
memory_cleanse(vchIV.data(), vchIV.size());
fKeySet = false;
}
CCrypter()
{
fKeySet = false;
vchKey.resize(WALLET_CRYPTO_KEY_SIZE);
vchIV.resize(WALLET_CRYPTO_IV_SIZE);
}
~CCrypter()
{
CleanKey();
}
};
/** Keystore which keeps the private keys encrypted.
* It derives from the basic key store, which is used if no encryption is active.
*/
class CCryptoKeyStore : public CBasicKeyStore
{
private:
CKeyingMaterial vMasterKey;
//! if fUseCrypto is true, mapKeys must be empty
//! if fUseCrypto is false, vMasterKey must be empty
std::atomic<bool> fUseCrypto;
//! keeps track of whether Unlock has run a thorough check before
bool fDecryptionThoroughlyChecked;
protected:
bool SetCrypted();
//! will encrypt previously unencrypted keys
bool EncryptKeys(CKeyingMaterial& vMasterKeyIn);
bool Unlock(const CKeyingMaterial& vMasterKeyIn);
CryptedKeyMap mapCryptedKeys;
public:
CCryptoKeyStore() : fUseCrypto(false), fDecryptionThoroughlyChecked(false)
{
}
bool IsCrypted() const
{
return fUseCrypto;
}
bool IsLocked() const
{
if (!IsCrypted())
return false;
bool result;
{
LOCK(cs_KeyStore);
result = vMasterKey.empty();
}
return result;
}
bool Lock();
virtual bool AddCryptedKey(const CPubKey &vchPubKey, const std::vector<unsigned char> &vchCryptedSecret);
bool AddKeyPubKey(const CKey& key, const CPubKey &pubkey) override;
bool HaveKey(const CKeyID &address) const override
{
{
LOCK(cs_KeyStore);
if (!IsCrypted()) {
return CBasicKeyStore::HaveKey(address);
}
return mapCryptedKeys.count(address) > 0;
}
return false;
}
bool GetKey(const CKeyID &address, CKey& keyOut) const override;
bool GetPubKey(const CKeyID &address, CPubKey& vchPubKeyOut) const override;
std::set<CKeyID> GetKeys() const override
{
LOCK(cs_KeyStore);
if (!IsCrypted()) {
return CBasicKeyStore::GetKeys();
}
std::set<CKeyID> set_address;
for (const auto& mi : mapCryptedKeys) {
set_address.insert(mi.first);
}
return set_address;
}
/**
* Wallet status (encrypted, locked) changed.
* Note: Called without locks held.
*/
boost::signals2::signal<void (CCryptoKeyStore* wallet)> NotifyStatusChanged;
};
#endif // BITCOIN_WALLET_CRYPTER_H
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