src/script/sigcache.h

   1 // Copyright (c) 2009-2010 Satoshi Nakamoto
   2 // Copyright (c) 2009-2017 The Bitcoin Core developers
   3 // Distributed under the MIT software license, see the accompanying
   4 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   5
   6 #ifndef BITCOIN_SCRIPT_SIGCACHE_H
   7 #define BITCOIN_SCRIPT_SIGCACHE_H
   8
   9 #include <script/interpreter.h>
  10
  11 #include <vector>
  12
  13 // DoS prevention: limit cache size to 32MB (over 1000000 entries on 64-bit
  14 // systems). Due to how we count cache size, actual memory usage is slightly
  15 // more (~32.25 MB)
  16 static const unsigned int DEFAULT_MAX_SIG_CACHE_SIZE = 32;
  17 // Maximum sig cache size allowed
  18 static const int64_t MAX_MAX_SIG_CACHE_SIZE = 16384;
  19
  20 class CPubKey;
  21
  22 /**
  23  * We're hashing a nonce into the entries themselves, so we don't need extra
  24  * blinding in the set hash computation.
  25  *
  26  * This may exhibit platform endian dependent behavior but because these are
  27  * nonced hashes (random) and this state is only ever used locally it is safe.
  28  * All that matters is local consistency.
  29  */
  30 class SignatureCacheHasher
  31 {
  32 public:
  33     template <uint8_t hash_select>
  34     uint32_t operator()(const uint256& key) const
  35     {
  36         static_assert(hash_select <8, "SignatureCacheHasher only has 8 hashes available.");
  37         uint32_t u;
  38         std::memcpy(&u, key.begin()+4*hash_select, 4);
  39         return u;
  40     }
  41 };
  42
  43 class CachingTransactionSignatureChecker : public TransactionSignatureChecker
  44 {
  45 private:
  46     bool store;
  47
  48 public:
  49     CachingTransactionSignatureChecker(const CTransaction* txToIn, unsigned int nInIn, const CAmount& amountIn, bool storeIn, PrecomputedTransactionData& txdataIn) : TransactionSignatureChecker(txToIn, nInIn, amountIn, txdataIn), store(storeIn) {}
  50
  51     bool VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& vchPubKey, const uint256& sighash) const override;
  52 };
  53
  54 void InitSignatureCache();
  55
  56 #endif // BITCOIN_SCRIPT_SIGCACHE_H