Use salted hasher instead of nonce in sigcache

Use salted hasher instead of nonce in Script Execution Cache

Don't read more than 32 bytes from GetRand

Apply g_* naming convention to scriptExecutionCache in validation.cpp

Fully apply g_* naming convention to scriptCacheHasher

Write same uint256 nonce twice for cache hash rather than calling getrand twice

Use salted hasher instead of nonce in sigcache

Use salted hasher instead of nonce in Script Execution Cache

Don't read more than 32 bytes from GetRand

Apply g_* naming convention to scriptExecutionCache in validation.cpp

Fully apply g_* naming convention to scriptCacheHasher

Write same uint256 nonce twice for cache hash rather than calling getrand twice

src/script/sigcache.cpp

@@ -23,7 +23,7 @@ class CSignatureCache
 {
 private:
      //! Entries are SHA256(nonce || signature hash || public key || signature):
-    uint256 nonce;
+    CSHA256 m_salted_hasher;
     typedef CuckooCache::cache<uint256, SignatureCacheHasher> map_type;
     map_type setValid;
     boost::shared_mutex cs_sigcache;
@@ -31,13 +31,19 @@ private:
 public:
     CSignatureCache()
     {
-        GetRandBytes(nonce.begin(), 32);
+        uint256 nonce = GetRandHash();
+        // We want the nonce to be 64 bytes long to force the hasher to process
+        // this chunk, which makes later hash computations more efficient. We
+        // just write our 32-byte entropy twice to fill the 64 bytes.
+        m_salted_hasher.Write(nonce.begin(), 32);
+        m_salted_hasher.Write(nonce.begin(), 32);
     }
 
     void
     ComputeEntry(uint256& entry, const uint256 &hash, const std::vector<unsigned char>& vchSig, const CPubKey& pubkey)
     {
-        CSHA256().Write(nonce.begin(), 32).Write(hash.begin(), 32).Write(&pubkey[0], pubkey.size()).Write(&vchSig[0], vchSig.size()).Finalize(entry.begin());
+        CSHA256 hasher = m_salted_hasher;
+        hasher.Write(hash.begin(), 32).Write(&pubkey[0], pubkey.size()).Write(&vchSig[0], vchSig.size()).Finalize(entry.begin());
     }
 
     bool