src/wallet/crypter.h

   1 // Copyright (c) 2009-2016 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 "keystore.h"
   9 #include "serialize.h"
  10 #include "support/allocators/secure.h"
  11
  12 const unsigned int WALLET_CRYPTO_KEY_SIZE = 32;
  13 const unsigned int WALLET_CRYPTO_SALT_SIZE = 8;
  14 const unsigned int WALLET_CRYPTO_IV_SIZE = 16;
  15
  16 /**
  17  * Private key encryption is done based on a CMasterKey,
  18  * which holds a salt and random encryption key.
  19  *
  20  * CMasterKeys are encrypted using AES-256-CBC using a key
  21  * derived using derivation method nDerivationMethod
  22  * (0 == EVP_sha512()) and derivation iterations nDeriveIterations.
  23  * vchOtherDerivationParameters is provided for alternative algorithms
  24  * which may require more parameters (such as scrypt).
  25  *
  26  * Wallet Private Keys are then encrypted using AES-256-CBC
  27  * with the double-sha256 of the public key as the IV, and the
  28  * master key's key as the encryption key (see keystore.[ch]).
  29  */
  30
  31 /** Master key for wallet encryption */
  32 class CMasterKey
  33 {
  34 public:
  35     std::vector<unsigned char> vchCryptedKey;
  36     std::vector<unsigned char> vchSalt;
  37     //! 0 = EVP_sha512()
  38     //! 1 = scrypt()
  39     unsigned int nDerivationMethod;
  40     unsigned int nDeriveIterations;
  41     //! Use this for more parameters to key derivation,
  42     //! such as the various parameters to scrypt
  43     std::vector<unsigned char> vchOtherDerivationParameters;
  44
  45     ADD_SERIALIZE_METHODS;
  46
  47     template <typename Stream, typename Operation>
  48     inline void SerializationOp(Stream& s, Operation ser_action) {
  49         READWRITE(vchCryptedKey);
  50         READWRITE(vchSalt);
  51         READWRITE(nDerivationMethod);
  52         READWRITE(nDeriveIterations);
  53         READWRITE(vchOtherDerivationParameters);
  54     }
  55
  56     CMasterKey()
  57     {
  58         // 25000 rounds is just under 0.1 seconds on a 1.86 GHz Pentium M
  59         // ie slightly lower than the lowest hardware we need bother supporting
  60         nDeriveIterations = 25000;
  61         nDerivationMethod = 0;
  62         vchOtherDerivationParameters = std::vector<unsigned char>(0);
  63     }
  64 };
  65
  66 typedef std::vector<unsigned char, secure_allocator<unsigned char> > CKeyingMaterial;
  67
  68 namespace wallet_crypto
  69 {
  70     class TestCrypter;
  71 }
  72
  73 /** Encryption/decryption context with key information */
  74 class CCrypter
  75 {
  76 friend class wallet_crypto::TestCrypter; // for test access to chKey/chIV
  77 private:
  78     std::vector<unsigned char, secure_allocator<unsigned char>> vchKey;
  79     std::vector<unsigned char, secure_allocator<unsigned char>> vchIV;
  80     bool fKeySet;
  81
  82     int BytesToKeySHA512AES(const std::vector<unsigned char>& chSalt, const SecureString& strKeyData, int count, unsigned char *key,unsigned char *iv) const;
  83
  84 public:
  85     bool SetKeyFromPassphrase(const SecureString &strKeyData, const std::vector<unsigned char>& chSalt, const unsigned int nRounds, const unsigned int nDerivationMethod);
  86     bool Encrypt(const CKeyingMaterial& vchPlaintext, std::vector<unsigned char> &vchCiphertext) const;
  87     bool Decrypt(const std::vector<unsigned char>& vchCiphertext, CKeyingMaterial& vchPlaintext) const;
  88     bool SetKey(const CKeyingMaterial& chNewKey, const std::vector<unsigned char>& chNewIV);
  89
  90     void CleanKey()
  91     {
  92         memory_cleanse(vchKey.data(), vchKey.size());
  93         memory_cleanse(vchIV.data(), vchIV.size());
  94         fKeySet = false;
  95     }
  96
  97     CCrypter()
  98     {
  99         fKeySet = false;
 100         vchKey.resize(WALLET_CRYPTO_KEY_SIZE);
 101         vchIV.resize(WALLET_CRYPTO_IV_SIZE);
 102     }
 103
 104     ~CCrypter()
 105     {
 106         CleanKey();
 107     }
 108 };
 109
 110 /** Keystore which keeps the private keys encrypted.
 111  * It derives from the basic key store, which is used if no encryption is active.
 112  */
 113 class CCryptoKeyStore : public CBasicKeyStore
 114 {
 115 private:
 116     CryptedKeyMap mapCryptedKeys;
 117
 118     CKeyingMaterial vMasterKey;
 119
 120     //! if fUseCrypto is true, mapKeys must be empty
 121     //! if fUseCrypto is false, vMasterKey must be empty
 122     bool fUseCrypto;
 123
 124     //! keeps track of whether Unlock has run a thorough check before
 125     bool fDecryptionThoroughlyChecked;
 126
 127 protected:
 128     bool SetCrypted();
 129
 130     //! will encrypt previously unencrypted keys
 131     bool EncryptKeys(CKeyingMaterial& vMasterKeyIn);
 132
 133     bool Unlock(const CKeyingMaterial& vMasterKeyIn);
 134
 135 public:
 136     CCryptoKeyStore() : fUseCrypto(false), fDecryptionThoroughlyChecked(false)
 137     {
 138     }
 139
 140     bool IsCrypted() const
 141     {
 142         return fUseCrypto;
 143     }
 144
 145     bool IsLocked() const
 146     {
 147         if (!IsCrypted())
 148             return false;
 149         bool result;
 150         {
 151             LOCK(cs_KeyStore);
 152             result = vMasterKey.empty();
 153         }
 154         return result;
 155     }
 156
 157     bool Lock();
 158
 159     virtual bool AddCryptedKey(const CPubKey &vchPubKey, const std::vector<unsigned char> &vchCryptedSecret);
 160     bool AddKeyPubKey(const CKey& key, const CPubKey &pubkey) override;
 161     bool HaveKey(const CKeyID &address) const override
 162     {
 163         {
 164             LOCK(cs_KeyStore);
 165             if (!IsCrypted())
 166                 return CBasicKeyStore::HaveKey(address);
 167             return mapCryptedKeys.count(address) > 0;
 168         }
 169         return false;
 170     }
 171     bool GetKey(const CKeyID &address, CKey& keyOut) const override;
 172     bool GetPubKey(const CKeyID &address, CPubKey& vchPubKeyOut) const override;
 173     void GetKeys(std::set<CKeyID> &setAddress) const override
 174     {
 175         if (!IsCrypted())
 176         {
 177             CBasicKeyStore::GetKeys(setAddress);
 178             return;
 179         }
 180         setAddress.clear();
 181         CryptedKeyMap::const_iterator mi = mapCryptedKeys.begin();
 182         while (mi != mapCryptedKeys.end())
 183         {
 184             setAddress.insert((*mi).first);
 185             mi++;
 186         }
 187     }
 188
 189     /**
 190      * Wallet status (encrypted, locked) changed.
 191      * Note: Called without locks held.
 192      */
 193     boost::signals2::signal<void (CCryptoKeyStore* wallet)> NotifyStatusChanged;
 194 };
 195
 196 #endif // BITCOIN_WALLET_CRYPTER_H