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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2016 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include "script/sign.h"
#include "key.h"
#include "keystore.h"
#include "policy/policy.h"
#include "primitives/transaction.h"
#include "script/standard.h"
#include "uint256.h"
#include <boost/foreach.hpp>
typedef std::vector<unsigned char> valtype;
TransactionSignatureCreator::TransactionSignatureCreator(const CKeyStore* keystoreIn, const CTransaction* txToIn, unsigned int nInIn, const CAmount& amountIn, int nHashTypeIn) : BaseSignatureCreator(keystoreIn), txTo(txToIn), nIn(nInIn), nHashType(nHashTypeIn), amount(amountIn), checker(txTo, nIn, amountIn) {}
bool TransactionSignatureCreator::CreateSig(std::vector<unsigned char>& vchSig, const CKeyID& address, const CScript& scriptCode, SigVersion sigversion) const
{
CKey key;
if (!keystore->GetKey(address, key))
return false;
// Signing with uncompressed keys is disabled in witness scripts
if (sigversion == SIGVERSION_WITNESS_V0 && !key.IsCompressed())
return false;
uint256 hash = SignatureHash(scriptCode, *txTo, nIn, nHashType, amount, sigversion);
if (!key.Sign(hash, vchSig))
return false;
vchSig.push_back((unsigned char)nHashType);
return true;
}
static bool Sign1(const CKeyID& address, const BaseSignatureCreator& creator, const CScript& scriptCode, std::vector<valtype>& ret, SigVersion sigversion)
{
std::vector<unsigned char> vchSig;
if (!creator.CreateSig(vchSig, address, scriptCode, sigversion))
return false;
ret.push_back(vchSig);
return true;
}
static bool SignN(const std::vector<valtype>& multisigdata, const BaseSignatureCreator& creator, const CScript& scriptCode, std::vector<valtype>& ret, SigVersion sigversion)
{
int nSigned = 0;
int nRequired = multisigdata.front()[0];
for (unsigned int i = 1; i < multisigdata.size()-1 && nSigned < nRequired; i++)
{
const valtype& pubkey = multisigdata[i];
CKeyID keyID = CPubKey(pubkey).GetID();
if (Sign1(keyID, creator, scriptCode, ret, sigversion))
++nSigned;
}
return nSigned==nRequired;
}
/**
* Sign scriptPubKey using signature made with creator.
* Signatures are returned in scriptSigRet (or returns false if scriptPubKey can't be signed),
* unless whichTypeRet is TX_SCRIPTHASH, in which case scriptSigRet is the redemption script.
* Returns false if scriptPubKey could not be completely satisfied.
*/
static bool SignStep(const BaseSignatureCreator& creator, const CScript& scriptPubKey,
std::vector<valtype>& ret, txnouttype& whichTypeRet, SigVersion sigversion)
{
CScript scriptRet;
uint160 h160;
ret.clear();
std::vector<valtype> vSolutions;
if (!Solver(scriptPubKey, whichTypeRet, vSolutions))
return false;
CKeyID keyID;
switch (whichTypeRet)
{
case TX_NONSTANDARD:
case TX_NULL_DATA:
return false;
case TX_PUBKEY:
keyID = CPubKey(vSolutions[0]).GetID();
return Sign1(keyID, creator, scriptPubKey, ret, sigversion);
case TX_PUBKEYHASH:
keyID = CKeyID(uint160(vSolutions[0]));
if (!Sign1(keyID, creator, scriptPubKey, ret, sigversion))
return false;
else
{
CPubKey vch;
creator.KeyStore().GetPubKey(keyID, vch);
ret.push_back(ToByteVector(vch));
}
return true;
case TX_SCRIPTHASH:
if (creator.KeyStore().GetCScript(uint160(vSolutions[0]), scriptRet)) {
ret.push_back(std::vector<unsigned char>(scriptRet.begin(), scriptRet.end()));
return true;
}
return false;
case TX_MULTISIG:
ret.push_back(valtype()); // workaround CHECKMULTISIG bug
return (SignN(vSolutions, creator, scriptPubKey, ret, sigversion));
case TX_WITNESS_V0_KEYHASH:
ret.push_back(vSolutions[0]);
return true;
case TX_WITNESS_V0_SCRIPTHASH:
CRIPEMD160().Write(&vSolutions[0][0], vSolutions[0].size()).Finalize(h160.begin());
if (creator.KeyStore().GetCScript(h160, scriptRet)) {
ret.push_back(std::vector<unsigned char>(scriptRet.begin(), scriptRet.end()));
return true;
}
return false;
default:
return false;
}
}
static CScript PushAll(const std::vector<valtype>& values)
{
CScript result;
BOOST_FOREACH(const valtype& v, values) {
if (v.size() == 0) {
result << OP_0;
} else if (v.size() == 1 && v[0] >= 1 && v[0] <= 16) {
result << CScript::EncodeOP_N(v[0]);
} else {
result << v;
}
}
return result;
}
bool ProduceSignature(const BaseSignatureCreator& creator, const CScript& fromPubKey, SignatureData& sigdata)
{
CScript script = fromPubKey;
bool solved = true;
std::vector<valtype> result;
txnouttype whichType;
solved = SignStep(creator, script, result, whichType, SIGVERSION_BASE);
bool P2SH = false;
CScript subscript;
sigdata.scriptWitness.stack.clear();
if (solved && whichType == TX_SCRIPTHASH)
{
// Solver returns the subscript that needs to be evaluated;
// the final scriptSig is the signatures from that
// and then the serialized subscript:
script = subscript = CScript(result[0].begin(), result[0].end());
solved = solved && SignStep(creator, script, result, whichType, SIGVERSION_BASE) && whichType != TX_SCRIPTHASH;
P2SH = true;
}
if (solved && whichType == TX_WITNESS_V0_KEYHASH)
{
CScript witnessscript;
witnessscript << OP_DUP << OP_HASH160 << ToByteVector(result[0]) << OP_EQUALVERIFY << OP_CHECKSIG;
txnouttype subType;
solved = solved && SignStep(creator, witnessscript, result, subType, SIGVERSION_WITNESS_V0);
sigdata.scriptWitness.stack = result;
result.clear();
}
else if (solved && whichType == TX_WITNESS_V0_SCRIPTHASH)
{
CScript witnessscript(result[0].begin(), result[0].end());
txnouttype subType;
solved = solved && SignStep(creator, witnessscript, result, subType, SIGVERSION_WITNESS_V0) && subType != TX_SCRIPTHASH && subType != TX_WITNESS_V0_SCRIPTHASH && subType != TX_WITNESS_V0_KEYHASH;
result.push_back(std::vector<unsigned char>(witnessscript.begin(), witnessscript.end()));
sigdata.scriptWitness.stack = result;
result.clear();
}
if (P2SH) {
result.push_back(std::vector<unsigned char>(subscript.begin(), subscript.end()));
}
sigdata.scriptSig = PushAll(result);
// Test solution
return solved && VerifyScript(sigdata.scriptSig, fromPubKey, &sigdata.scriptWitness, STANDARD_SCRIPT_VERIFY_FLAGS, creator.Checker());
}
SignatureData DataFromTransaction(const CMutableTransaction& tx, unsigned int nIn)
{
SignatureData data;
assert(tx.vin.size() > nIn);
data.scriptSig = tx.vin[nIn].scriptSig;
data.scriptWitness = tx.vin[nIn].scriptWitness;
return data;
}
void UpdateTransaction(CMutableTransaction& tx, unsigned int nIn, const SignatureData& data)
{
assert(tx.vin.size() > nIn);
tx.vin[nIn].scriptSig = data.scriptSig;
tx.vin[nIn].scriptWitness = data.scriptWitness;
}
bool SignSignature(const CKeyStore &keystore, const CScript& fromPubKey, CMutableTransaction& txTo, unsigned int nIn, const CAmount& amount, int nHashType)
{
assert(nIn < txTo.vin.size());
CTransaction txToConst(txTo);
TransactionSignatureCreator creator(&keystore, &txToConst, nIn, amount, nHashType);
SignatureData sigdata;
bool ret = ProduceSignature(creator, fromPubKey, sigdata);
UpdateTransaction(txTo, nIn, sigdata);
return ret;
}
bool SignSignature(const CKeyStore &keystore, const CTransaction& txFrom, CMutableTransaction& txTo, unsigned int nIn, int nHashType)
{
assert(nIn < txTo.vin.size());
CTxIn& txin = txTo.vin[nIn];
assert(txin.prevout.n < txFrom.vout.size());
const CTxOut& txout = txFrom.vout[txin.prevout.n];
return SignSignature(keystore, txout.scriptPubKey, txTo, nIn, txout.nValue, nHashType);
}
static std::vector<valtype> CombineMultisig(const CScript& scriptPubKey, const BaseSignatureChecker& checker,
const std::vector<valtype>& vSolutions,
const std::vector<valtype>& sigs1, const std::vector<valtype>& sigs2, SigVersion sigversion)
{
// Combine all the signatures we've got:
std::set<valtype> allsigs;
BOOST_FOREACH(const valtype& v, sigs1)
{
if (!v.empty())
allsigs.insert(v);
}
BOOST_FOREACH(const valtype& v, sigs2)
{
if (!v.empty())
allsigs.insert(v);
}
// Build a map of pubkey -> signature by matching sigs to pubkeys:
assert(vSolutions.size() > 1);
unsigned int nSigsRequired = vSolutions.front()[0];
unsigned int nPubKeys = vSolutions.size()-2;
std::map<valtype, valtype> sigs;
BOOST_FOREACH(const valtype& sig, allsigs)
{
for (unsigned int i = 0; i < nPubKeys; i++)
{
const valtype& pubkey = vSolutions[i+1];
if (sigs.count(pubkey))
continue; // Already got a sig for this pubkey
if (checker.CheckSig(sig, pubkey, scriptPubKey, sigversion))
{
sigs[pubkey] = sig;
break;
}
}
}
// Now build a merged CScript:
unsigned int nSigsHave = 0;
std::vector<valtype> result; result.push_back(valtype()); // pop-one-too-many workaround
for (unsigned int i = 0; i < nPubKeys && nSigsHave < nSigsRequired; i++)
{
if (sigs.count(vSolutions[i+1]))
{
result.push_back(sigs[vSolutions[i+1]]);
++nSigsHave;
}
}
// Fill any missing with OP_0:
for (unsigned int i = nSigsHave; i < nSigsRequired; i++)
result.push_back(valtype());
return result;
}
namespace
{
struct Stacks
{
std::vector<valtype> script;
std::vector<valtype> witness;
Stacks() {}
explicit Stacks(const std::vector<valtype>& scriptSigStack_) : script(scriptSigStack_), witness() {}
explicit Stacks(const SignatureData& data) : witness(data.scriptWitness.stack) {
EvalScript(script, data.scriptSig, SCRIPT_VERIFY_STRICTENC, BaseSignatureChecker(), SIGVERSION_BASE);
}
SignatureData Output() const {
SignatureData result;
result.scriptSig = PushAll(script);
result.scriptWitness.stack = witness;
return result;
}
};
}
static Stacks CombineSignatures(const CScript& scriptPubKey, const BaseSignatureChecker& checker,
const txnouttype txType, const std::vector<valtype>& vSolutions,
Stacks sigs1, Stacks sigs2, SigVersion sigversion)
{
switch (txType)
{
case TX_NONSTANDARD:
case TX_NULL_DATA:
// Don't know anything about this, assume bigger one is correct:
if (sigs1.script.size() >= sigs2.script.size())
return sigs1;
return sigs2;
case TX_PUBKEY:
case TX_PUBKEYHASH:
// Signatures are bigger than placeholders or empty scripts:
if (sigs1.script.empty() || sigs1.script[0].empty())
return sigs2;
return sigs1;
case TX_WITNESS_V0_KEYHASH:
// Signatures are bigger than placeholders or empty scripts:
if (sigs1.witness.empty() || sigs1.witness[0].empty())
return sigs2;
return sigs1;
case TX_SCRIPTHASH:
if (sigs1.script.empty() || sigs1.script.back().empty())
return sigs2;
else if (sigs2.script.empty() || sigs2.script.back().empty())
return sigs1;
else
{
// Recur to combine:
valtype spk = sigs1.script.back();
CScript pubKey2(spk.begin(), spk.end());
txnouttype txType2;
std::vector<std::vector<unsigned char> > vSolutions2;
Solver(pubKey2, txType2, vSolutions2);
sigs1.script.pop_back();
sigs2.script.pop_back();
Stacks result = CombineSignatures(pubKey2, checker, txType2, vSolutions2, sigs1, sigs2, sigversion);
result.script.push_back(spk);
return result;
}
case TX_MULTISIG:
return Stacks(CombineMultisig(scriptPubKey, checker, vSolutions, sigs1.script, sigs2.script, sigversion));
case TX_WITNESS_V0_SCRIPTHASH:
if (sigs1.witness.empty() || sigs1.witness.back().empty())
return sigs2;
else if (sigs2.witness.empty() || sigs2.witness.back().empty())
return sigs1;
else
{
// Recur to combine:
CScript pubKey2(sigs1.witness.back().begin(), sigs1.witness.back().end());
txnouttype txType2;
std::vector<valtype> vSolutions2;
Solver(pubKey2, txType2, vSolutions2);
sigs1.witness.pop_back();
sigs1.script = sigs1.witness;
sigs1.witness.clear();
sigs2.witness.pop_back();
sigs2.script = sigs2.witness;
sigs2.witness.clear();
Stacks result = CombineSignatures(pubKey2, checker, txType2, vSolutions2, sigs1, sigs2, SIGVERSION_WITNESS_V0);
result.witness = result.script;
result.script.clear();
result.witness.push_back(valtype(pubKey2.begin(), pubKey2.end()));
return result;
}
default:
return Stacks();
}
}
SignatureData CombineSignatures(const CScript& scriptPubKey, const BaseSignatureChecker& checker,
const SignatureData& scriptSig1, const SignatureData& scriptSig2)
{
txnouttype txType;
std::vector<std::vector<unsigned char> > vSolutions;
Solver(scriptPubKey, txType, vSolutions);
return CombineSignatures(scriptPubKey, checker, txType, vSolutions, Stacks(scriptSig1), Stacks(scriptSig2), SIGVERSION_BASE).Output();
}
namespace {
/** Dummy signature checker which accepts all signatures. */
class DummySignatureChecker : public BaseSignatureChecker
{
public:
DummySignatureChecker() {}
bool CheckSig(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, SigVersion sigversion) const
{
return true;
}
};
const DummySignatureChecker dummyChecker;
}
const BaseSignatureChecker& DummySignatureCreator::Checker() const
{
return dummyChecker;
}
bool DummySignatureCreator::CreateSig(std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode, SigVersion sigversion) const
{
// Create a dummy signature that is a valid DER-encoding
vchSig.assign(72, '\000');
vchSig[0] = 0x30;
vchSig[1] = 69;
vchSig[2] = 0x02;
vchSig[3] = 33;
vchSig[4] = 0x01;
vchSig[4 + 33] = 0x02;
vchSig[5 + 33] = 32;
vchSig[6 + 33] = 0x01;
vchSig[6 + 33 + 32] = SIGHASH_ALL;
return true;
}