Move signature cache from CKey::Verify to CheckSig in script.cpp

More than doubles the speed of verifying already-cached signatures
that use compressed pubkeys:
Before: ~200 microseconds
After:  ~80 microseconds
(no caching at all: ~3,300 microseconds per signature)

Also encapsulates the signature cache code in a class
and fixes a signed/unsigned comparison warning.

1 files changed, 0 insertions, 65 deletions

diff --git a/src/key.cpp b/src/key.cpp
index 4172d6be5e..9485b477cb 100644
--- a/src/key.cpp
+++ b/src/key.cpp
@@ -4,13 +4,10 @@
 
 #include <map>
 
-#include <boost/tuple/tuple.hpp>
 #include <openssl/ecdsa.h>
 #include <openssl/obj_mac.h>
 
 #include "key.h"
-#include "sync.h"
-#include "util.h"
 
 // Generate a private key from just the secret parameter
 int EC_KEY_regenerate_key(EC_KEY *eckey, BIGNUM *priv_key)
@@ -352,85 +349,23 @@ bool CKey::SetCompactSignature(uint256 hash, const std::vector<unsigned char>& v
     return false;
 }
 
-// Valid signature cache, to avoid doing expensive ECDSA signature checking
-// twice for every transaction (once when accepted into memory pool, and
-// again when accepted into the block chain)
-
-// sigdata_type is (signature hash, signature, public key):
-typedef boost::tuple<uint256, std::vector<unsigned char>, std::vector<unsigned char> > sigdata_type;
-static std::set< sigdata_type> setValidSigCache;
-static CCriticalSection cs_sigcache;
-
-static bool
-GetValidSigCache(uint256 hash, const std::vector<unsigned char>& vchSig, const std::vector<unsigned char>& pubKey)
-{
-    LOCK(cs_sigcache);
-
-    sigdata_type k(hash, vchSig, pubKey);
-    std::set<sigdata_type>::iterator mi = setValidSigCache.find(k);
-    if (mi != setValidSigCache.end())
-        return true;
-    return false;
-}
-
-static void
-SetValidSigCache(uint256 hash, const std::vector<unsigned char>& vchSig, const std::vector<unsigned char>& pubKey)
-{
-    // DoS prevention: limit cache size to less than 10MB
-    // (~200 bytes per cache entry times 50,000 entries)
-    // Since there are a maximum of 20,000 signature operations per block
-    // 50,000 is a reasonable default.
-    int64 nMaxCacheSize = GetArg("-maxsigcachesize", 50000);
-    if (nMaxCacheSize <= 0) return;
-
-    LOCK(cs_sigcache);
-
-    while (setValidSigCache.size() > nMaxCacheSize)
-    {
-        // Evict a random entry. Random because that helps
-        // foil would-be DoS attackers who might try to pre-generate
-        // and re-use a set of valid signatures just-slightly-greater
-        // than our cache size.
-        uint256 randomHash = GetRandHash();
-        std::vector<unsigned char> unused;
-        std::set<sigdata_type>::iterator it =
-            setValidSigCache.lower_bound(sigdata_type(randomHash, unused, unused));
-        if (it == setValidSigCache.end())
-            it = setValidSigCache.begin();
-        setValidSigCache.erase(*it);
-    }
-
-    sigdata_type k(hash, vchSig, pubKey);
-    setValidSigCache.insert(k);
-}
-
-
 bool CKey::Verify(uint256 hash, const std::vector<unsigned char>& vchSig)
 {
-    if (GetValidSigCache(hash, vchSig, GetPubKey()))
-        return true;
-
     // -1 = error, 0 = bad sig, 1 = good
     if (ECDSA_verify(0, (unsigned char*)&hash, sizeof(hash), &vchSig[0], vchSig.size(), pkey) != 1)
         return false;
 
-    // good sig
-    SetValidSigCache(hash, vchSig, GetPubKey());
     return true;
 }
 
 bool CKey::VerifyCompact(uint256 hash, const std::vector<unsigned char>& vchSig)
 {
-    if (GetValidSigCache(hash, vchSig, GetPubKey()))
-        return true;
-
     CKey key;
     if (!key.SetCompactSignature(hash, vchSig))
         return false;
     if (GetPubKey() != key.GetPubKey())
         return false;
 
-    SetValidSigCache(hash, vchSig, GetPubKey());
     return true;
 }