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// Copyright (c) 2009-2021 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 <serialize.h>
#include <support/allocators/secure.h>
#include <script/signingprovider.h>
namespace wallet {
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;
SERIALIZE_METHODS(CMasterKey, obj)
{
READWRITE(obj.vchCryptedKey, obj.vchSalt, obj.nDerivationMethod, obj.nDeriveIterations, obj.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_tests
{
class TestCrypter;
}
/** Encryption/decryption context with key information */
class CCrypter
{
friend class wallet_crypto_tests::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(std::span<const unsigned char> salt, const SecureString& key_data, int count, unsigned char* key, unsigned char* iv) const;
public:
bool SetKeyFromPassphrase(const SecureString& key_data, std::span<const unsigned char> salt, const unsigned int rounds, const unsigned int derivation_method);
bool Encrypt(const CKeyingMaterial& vchPlaintext, std::vector<unsigned char> &vchCiphertext) const;
bool Decrypt(std::span<const unsigned char> ciphertext, CKeyingMaterial& plaintext) const;
bool SetKey(const CKeyingMaterial& new_key, std::span<const unsigned char> new_iv);
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();
}
};
bool EncryptSecret(const CKeyingMaterial& vMasterKey, const CKeyingMaterial &vchPlaintext, const uint256& nIV, std::vector<unsigned char> &vchCiphertext);
bool DecryptSecret(const CKeyingMaterial& master_key, std::span<const unsigned char> ciphertext, const uint256& iv, CKeyingMaterial& plaintext);
bool DecryptKey(const CKeyingMaterial& master_key, std::span<const unsigned char> crypted_secret, const CPubKey& pub_key, CKey& key);
} // namespace wallet
#endif // BITCOIN_WALLET_CRYPTER_H
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