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       1                 :             : // Copyright (c) 2009-2021 The Bitcoin Core developers
       2                 :             : // Distributed under the MIT software license, see the accompanying
       3                 :             : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
       4                 :             : 
       5                 :             : #ifndef BITCOIN_WALLET_CRYPTER_H
       6                 :             : #define BITCOIN_WALLET_CRYPTER_H
       7                 :             : 
       8                 :             : #include <serialize.h>
       9                 :             : #include <support/allocators/secure.h>
      10                 :             : #include <script/signingprovider.h>
      11                 :             : 
      12                 :             : 
      13                 :             : namespace wallet {
      14                 :             : const unsigned int WALLET_CRYPTO_KEY_SIZE = 32;
      15                 :             : const unsigned int WALLET_CRYPTO_SALT_SIZE = 8;
      16                 :             : const unsigned int WALLET_CRYPTO_IV_SIZE = 16;
      17                 :             : 
      18                 :             : /**
      19                 :             :  * Private key encryption is done based on a CMasterKey,
      20                 :             :  * which holds a salt and random encryption key.
      21                 :             :  *
      22                 :             :  * CMasterKeys are encrypted using AES-256-CBC using a key
      23                 :             :  * derived using derivation method nDerivationMethod
      24                 :             :  * (0 == EVP_sha512()) and derivation iterations nDeriveIterations.
      25                 :             :  * vchOtherDerivationParameters is provided for alternative algorithms
      26                 :             :  * which may require more parameters.
      27                 :             :  *
      28                 :             :  * Wallet Private Keys are then encrypted using AES-256-CBC
      29                 :             :  * with the double-sha256 of the public key as the IV, and the
      30                 :             :  * master key's key as the encryption key (see keystore.[ch]).
      31                 :             :  */
      32                 :             : 
      33                 :             : /** Master key for wallet encryption */
      34                 :             : class CMasterKey
      35                 :             : {
      36                 :             : public:
      37                 :             :     std::vector<unsigned char> vchCryptedKey;
      38                 :             :     std::vector<unsigned char> vchSalt;
      39                 :             :     //! 0 = EVP_sha512()
      40                 :             :     unsigned int nDerivationMethod;
      41                 :             :     unsigned int nDeriveIterations;
      42                 :             :     //! Use this for more parameters to key derivation (currently unused)
      43                 :             :     std::vector<unsigned char> vchOtherDerivationParameters;
      44                 :             : 
      45                 :             :     //! Default/minimum number of key derivation rounds
      46                 :             :     // 25000 rounds is just under 0.1 seconds on a 1.86 GHz Pentium M
      47                 :             :     // ie slightly lower than the lowest hardware we need bother supporting
      48                 :             :     static constexpr unsigned int DEFAULT_DERIVE_ITERATIONS = 25000;
      49                 :             : 
      50                 :           0 :     SERIALIZE_METHODS(CMasterKey, obj)
      51                 :             :     {
      52                 :           0 :         READWRITE(obj.vchCryptedKey, obj.vchSalt, obj.nDerivationMethod, obj.nDeriveIterations, obj.vchOtherDerivationParameters);
      53                 :             :     }
      54                 :             : 
      55                 :           0 :     CMasterKey()
      56         [ #  # ]:           0 :     {
      57                 :           0 :         nDeriveIterations = DEFAULT_DERIVE_ITERATIONS;
      58                 :           0 :         nDerivationMethod = 0;
      59         [ #  # ]:           0 :         vchOtherDerivationParameters = std::vector<unsigned char>(0);
      60                 :           0 :     }
      61                 :             : };
      62                 :             : 
      63                 :             : typedef std::vector<unsigned char, secure_allocator<unsigned char> > CKeyingMaterial;
      64                 :             : 
      65                 :             : namespace wallet_crypto_tests
      66                 :             : {
      67                 :             :     class TestCrypter;
      68                 :             : }
      69                 :             : 
      70                 :             : /** Encryption/decryption context with key information */
      71                 :             : class CCrypter
      72                 :             : {
      73                 :             : friend class wallet_crypto_tests::TestCrypter; // for test access to chKey/chIV
      74                 :             : private:
      75                 :             :     std::vector<unsigned char, secure_allocator<unsigned char>> vchKey;
      76                 :             :     std::vector<unsigned char, secure_allocator<unsigned char>> vchIV;
      77                 :             :     bool fKeySet;
      78                 :             : 
      79                 :             :     int BytesToKeySHA512AES(std::span<const unsigned char> salt, const SecureString& key_data, int count, unsigned char* key, unsigned char* iv) const;
      80                 :             : 
      81                 :             : public:
      82                 :             :     bool SetKeyFromPassphrase(const SecureString& key_data, std::span<const unsigned char> salt, const unsigned int rounds, const unsigned int derivation_method);
      83                 :             :     bool Encrypt(const CKeyingMaterial& vchPlaintext, std::vector<unsigned char> &vchCiphertext) const;
      84                 :             :     bool Decrypt(std::span<const unsigned char> ciphertext, CKeyingMaterial& plaintext) const;
      85                 :             :     bool SetKey(const CKeyingMaterial& new_key, std::span<const unsigned char> new_iv);
      86                 :             : 
      87                 :        2050 :     void CleanKey()
      88                 :             :     {
      89                 :        2050 :         memory_cleanse(vchKey.data(), vchKey.size());
      90                 :        2050 :         memory_cleanse(vchIV.data(), vchIV.size());
      91                 :        2050 :         fKeySet = false;
      92                 :        2050 :     }
      93                 :             : 
      94                 :        2050 :     CCrypter()
      95         [ +  - ]:        2050 :     {
      96                 :        2050 :         fKeySet = false;
      97         [ +  - ]:        2050 :         vchKey.resize(WALLET_CRYPTO_KEY_SIZE);
      98         [ +  - ]:        2050 :         vchIV.resize(WALLET_CRYPTO_IV_SIZE);
      99                 :        2050 :     }
     100                 :             : 
     101                 :        2050 :     ~CCrypter()
     102                 :             :     {
     103                 :        2050 :         CleanKey();
     104                 :        2050 :     }
     105                 :             : };
     106                 :             : 
     107                 :             : bool EncryptSecret(const CKeyingMaterial& vMasterKey, const CKeyingMaterial &vchPlaintext, const uint256& nIV, std::vector<unsigned char> &vchCiphertext);
     108                 :             : bool DecryptSecret(const CKeyingMaterial& master_key, std::span<const unsigned char> ciphertext, const uint256& iv, CKeyingMaterial& plaintext);
     109                 :             : bool DecryptKey(const CKeyingMaterial& master_key, std::span<const unsigned char> crypted_secret, const CPubKey& pub_key, CKey& key);
     110                 :             : } // namespace wallet
     111                 :             : 
     112                 :             : #endif // BITCOIN_WALLET_CRYPTER_H