Compact serialization for scripts
Special serializers for script which detect common cases and encode them much more efficiently. 3 special cases are defined: * Pay to pubkey hash (encoded as 21 bytes) * Pay to script hash (encoded as 21 bytes) * Pay to pubkey starting with 0x02, 0x03 or 0x04 (encoded as 33 bytes) Other scripts up to 121 bytes require 1 byte + script length. Above that, scripts up to 16505 bytes require 2 bytes + script length.
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5 changed files with 213 additions and 4 deletions
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@ -120,9 +120,9 @@ err:
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return ret;
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return ret;
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}
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}
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void CKey::SetCompressedPubKey()
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void CKey::SetCompressedPubKey(bool fCompressed)
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{
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{
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EC_KEY_set_conv_form(pkey, POINT_CONVERSION_COMPRESSED);
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EC_KEY_set_conv_form(pkey, fCompressed ? POINT_CONVERSION_COMPRESSED : POINT_CONVERSION_UNCOMPRESSED);
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fCompressedPubKey = true;
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fCompressedPubKey = true;
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}
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}
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@ -113,9 +113,8 @@ protected:
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bool fSet;
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bool fSet;
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bool fCompressedPubKey;
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bool fCompressedPubKey;
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void SetCompressedPubKey();
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public:
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public:
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void SetCompressedPubKey(bool fCompressed = true);
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void Reset();
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void Reset();
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14
src/main.h
14
src/main.h
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@ -647,6 +647,20 @@ protected:
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const CTxOut& GetOutputFor(const CTxIn& input, const MapPrevTx& inputs) const;
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const CTxOut& GetOutputFor(const CTxIn& input, const MapPrevTx& inputs) const;
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};
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};
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/** wrapper for CTxOut that provides a more compact serialization */
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class CTxOutCompressor
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{
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private:
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CTxOut &txout;
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public:
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CTxOutCompressor(CTxOut &txoutIn) : txout(txoutIn) { }
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IMPLEMENT_SERIALIZE(
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READWRITE(VARINT(txout.nValue));
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CScriptCompressor cscript(REF(txout.scriptPubKey));
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READWRITE(cscript);
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)
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};
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125
src/script.cpp
125
src/script.cpp
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@ -1951,3 +1951,128 @@ void CScript::SetMultisig(int nRequired, const std::vector<CKey>& keys)
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*this << key.GetPubKey();
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*this << key.GetPubKey();
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*this << EncodeOP_N(keys.size()) << OP_CHECKMULTISIG;
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*this << EncodeOP_N(keys.size()) << OP_CHECKMULTISIG;
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}
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}
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bool CScriptCompressor::IsToKeyID(CKeyID &hash) const
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{
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if (script.size() == 25 && script[0] == OP_DUP && script[1] == OP_HASH160
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&& script[2] == 20 && script[23] == OP_EQUALVERIFY
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&& script[24] == OP_CHECKSIG) {
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memcpy(&hash, &script[3], 20);
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return true;
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}
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return false;
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}
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bool CScriptCompressor::IsToScriptID(CScriptID &hash) const
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{
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if (script.size() == 23 && script[0] == OP_HASH160 && script[1] == 20
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&& script[22] == OP_EQUAL) {
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memcpy(&hash, &script[2], 20);
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return true;
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}
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return false;
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}
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bool CScriptCompressor::IsToPubKey(std::vector<unsigned char> &pubkey) const
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{
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if (script.size() == 35 && script[0] == 33 && script[34] == OP_CHECKSIG
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&& (script[1] == 0x02 || script[1] == 0x03)) {
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pubkey.resize(33);
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memcpy(&pubkey[0], &script[1], 33);
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return true;
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}
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if (script.size() == 67 && script[0] == 65 && script[66] == OP_CHECKSIG
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&& script[1] == 0x04) {
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pubkey.resize(65);
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memcpy(&pubkey[0], &script[1], 65);
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CKey key;
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return (key.SetPubKey(CPubKey(pubkey))); // SetPubKey fails if this is not a valid public key, a case that would not be compressible
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}
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return false;
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}
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bool CScriptCompressor::Compress(std::vector<unsigned char> &out) const
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{
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CKeyID keyID;
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if (IsToKeyID(keyID)) {
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out.resize(21);
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out[0] = 0x00;
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memcpy(&out[1], &keyID, 20);
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return true;
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}
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CScriptID scriptID;
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if (IsToScriptID(scriptID)) {
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out.resize(21);
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out[0] = 0x01;
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memcpy(&out[1], &scriptID, 20);
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return true;
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}
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std::vector<unsigned char> pubkey;
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if (IsToPubKey(pubkey)) {
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out.resize(33);
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memcpy(&out[1], &pubkey[1], 32);
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if (pubkey[0] == 0x02 || pubkey[0] == 0x03) {
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out[0] = pubkey[0];
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return true;
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} else if (pubkey[0] == 0x04) {
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out[0] = 0x04 | (pubkey[64] & 0x01);
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return true;
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}
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}
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return false;
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}
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unsigned int CScriptCompressor::GetSpecialSize(unsigned int nSize) const
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{
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if (nSize == 0 || nSize == 1)
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return 20;
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if (nSize == 2 || nSize == 3 || nSize == 4 || nSize == 5)
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return 32;
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return 0;
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}
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bool CScriptCompressor::Decompress(unsigned int nSize, const std::vector<unsigned char> &in)
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{
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switch(nSize) {
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case 0x00:
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script.resize(25);
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script[0] = OP_DUP;
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script[1] = OP_HASH160;
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script[2] = 20;
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memcpy(&script[3], &in[0], 20);
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script[23] = OP_EQUALVERIFY;
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script[24] = OP_CHECKSIG;
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return true;
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case 0x01:
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script.resize(23);
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script[0] = OP_HASH160;
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script[1] = 20;
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memcpy(&script[2], &in[0], 20);
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script[22] = OP_EQUAL;
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return true;
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case 0x02:
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case 0x03:
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script.resize(35);
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script[0] = 33;
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script[1] = nSize;
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memcpy(&script[2], &in[0], 32);
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script[34] = OP_CHECKSIG;
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return true;
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case 0x04:
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case 0x05:
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std::vector<unsigned char> vch(33, 0x00);
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vch[0] = nSize - 2;
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memcpy(&vch[1], &in[0], 32);
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CKey key;
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if (!key.SetPubKey(CPubKey(vch)))
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return false;
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key.SetCompressedPubKey(false); // Decompress public key
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CPubKey pubkey = key.GetPubKey();
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script.resize(67);
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script[0] = 65;
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memcpy(&script[1], &pubkey.Raw()[0], 65);
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script[66] = OP_CHECKSIG;
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return true;
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}
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return false;
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}
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71
src/script.h
71
src/script.h
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@ -579,7 +579,78 @@ public:
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}
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}
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};
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};
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/** Compact serializer for scripts.
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*
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* It detects common cases and encodes them much more efficiently.
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* 3 special cases are defined:
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* * Pay to pubkey hash (encoded as 21 bytes)
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* * Pay to script hash (encoded as 21 bytes)
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* * Pay to pubkey starting with 0x02, 0x03 or 0x04 (encoded as 33 bytes)
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*
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* Other scripts up to 121 bytes require 1 byte + script length. Above
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* that, scripts up to 16505 bytes require 2 bytes + script length.
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*/
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class CScriptCompressor
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{
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private:
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// make this static for now (there are only 6 special scripts defined)
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// this can potentially be extended together with a new nVersion for
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// transactions, in which case this value becomes dependent on nVersion
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// and nHeight of the enclosing transaction.
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static const unsigned int nSpecialScripts = 6;
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CScript &script;
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protected:
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// These check for scripts for which a special case with a shorter encoding is defined.
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// They are implemented separately from the CScript test, as these test for exact byte
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// sequence correspondences, and are more strict. For example, IsToPubKey also verifies
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// whether the public key is valid (as invalid ones cannot be represented in compressed
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// form).
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bool IsToKeyID(CKeyID &hash) const;
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bool IsToScriptID(CScriptID &hash) const;
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bool IsToPubKey(std::vector<unsigned char> &pubkey) const;
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bool Compress(std::vector<unsigned char> &out) const;
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unsigned int GetSpecialSize(unsigned int nSize) const;
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bool Decompress(unsigned int nSize, const std::vector<unsigned char> &out);
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public:
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CScriptCompressor(CScript &scriptIn) : script(scriptIn) { }
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unsigned int GetSerializeSize(int nType, int nVersion) const {
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std::vector<unsigned char> compr;
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if (Compress(compr))
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return compr.size();
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unsigned int nSize = script.size() + nSpecialScripts;
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return script.size() + VARINT(nSize).GetSerializeSize(nType, nVersion);
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}
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template<typename Stream>
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void Serialize(Stream &s, int nType, int nVersion) const {
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std::vector<unsigned char> compr;
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if (Compress(compr)) {
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s << CFlatData(&compr[0], &compr[compr.size()]);
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return;
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}
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unsigned int nSize = script.size() + nSpecialScripts;
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s << VARINT(nSize);
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s << CFlatData(&script[0], &script[script.size()]);
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}
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template<typename Stream>
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void Unserialize(Stream &s, int nType, int nVersion) {
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unsigned int nSize;
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s >> VARINT(nSize);
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if (nSize < nSpecialScripts) {
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std::vector<unsigned char> vch(GetSpecialSize(nSize), 0x00);
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s >> REF(CFlatData(&vch[0], &vch[vch.size()]));
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Decompress(nSize, vch);
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return;
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}
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nSize -= nSpecialScripts;
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script.resize(nSize);
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s >> REF(CFlatData(&script[0], &script[script.size()]));
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}
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};
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bool IsCanonicalPubKey(const std::vector<unsigned char> &vchPubKey);
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bool IsCanonicalPubKey(const std::vector<unsigned char> &vchPubKey);
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bool IsCanonicalSignature(const std::vector<unsigned char> &vchSig);
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bool IsCanonicalSignature(const std::vector<unsigned char> &vchSig);
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