Differential D1578 Diff 4345 src/script/sigencoding.cpp

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src/script/sigencoding.cpp

// Copyright (c) 2009-2010 Satoshi Nakamoto		// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2016 The Bitcoin Core developers		// Copyright (c) 2009-2016 The Bitcoin Core developers
// Copyright (c) 2017-2018 The Bitcoin developers		// Copyright (c) 2017-2018 The Bitcoin developers
// Distributed under the MIT software license, see the accompanying		// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.		// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include "sigencoding.h"		#include "sigencoding.h"

#include "pubkey.h"		#include "pubkey.h"
#include "script_flags.h"		#include "script_flags.h"

#include <boost/range/adaptor/sliced.hpp>		#include <boost/range/adaptor/sliced.hpp>

		typedef boost::sliced_range<const valtype> slicedvaltype;

/**		/**
* A canonical signature exists of: <30> <total len> <02> <len R> <R> <02> <len		* A canonical signature exists of: <30> <total len> <02> <len R> <R> <02> <len
* S> <S> <hashtype>, where R and S are not negative (their first byte has its		* S> <S> <hashtype>, where R and S are not negative (their first byte has its
* highest bit not set), and not excessively padded (do not start with a 0 byte,		* highest bit not set), and not excessively padded (do not start with a 0 byte,
* unless an otherwise negative number follows, in which case a single 0 byte is		* unless an otherwise negative number follows, in which case a single 0 byte is
* necessary and even required).		* necessary and even required).
*		*
* See https://bitcointalk.org/index.php?topic=8392.msg127623#msg127623		* See https://bitcointalk.org/index.php?topic=8392.msg127623#msg127623
*		*
* This function is consensus-critical since BIP66.		* This function is consensus-critical since BIP66.
*/		*/
static bool		static bool IsValidSignatureEncoding(const slicedvaltype &sig) {
IsValidSignatureEncoding(const boost::sliced_range<const valtype> &sig) {
// Format: 0x30 [total-length] 0x02 [R-length] [R] 0x02 [S-length] [S]		// Format: 0x30 [total-length] 0x02 [R-length] [R] 0x02 [S-length] [S]
// * total-length: 1-byte length descriptor of everything that follows,		// * total-length: 1-byte length descriptor of everything that follows,
// excluding the sighash byte.		// excluding the sighash byte.
// * R-length: 1-byte length descriptor of the R value that follows.		// * R-length: 1-byte length descriptor of the R value that follows.
// * R: arbitrary-length big-endian encoded R value. It must use the		// * R: arbitrary-length big-endian encoded R value. It must use the
// shortest possible encoding for a positive integers (which means no null		// shortest possible encoding for a positive integers (which means no null
// bytes at the start, except a single one when the next byte has its		// bytes at the start, except a single one when the next byte has its
// highest bit set).		// highest bit set).
▲ Show 20 Lines • Show All 108 Lines • ▼ Show 20 Lines	static bool IsValidSignatureEncoding(const slicedvaltype &sig) {
// our of bound elements.		// our of bound elements.
if (lenS > 1 && (sig[startS + 2] == 0x00) && !(sig[startS + 3] & 0x80)) {		if (lenS > 1 && (sig[startS + 2] == 0x00) && !(sig[startS + 3] & 0x80)) {
return false;		return false;
}		}

return true;		return true;
}		}

static bool IsLowDERSignature(const valtype &vchSig, ScriptError *serror) {		static bool CheckSignatureWithoutSigHashTypeEncoding(const slicedvaltype &sig,
assert(vchSig.size() > 0);		uint32_t flags,
if (CPubKey::CheckLowS(vchSig \|		ScriptError *serror) {
boost::adaptors::sliced(0, vchSig.size() - 1))) {		if ((flags & (SCRIPT_VERIFY_DERSIG \| SCRIPT_VERIFY_LOW_S \|
return true;		SCRIPT_VERIFY_STRICTENC)) &&
		!IsValidSignatureEncoding(sig)) {
		return set_error(serror, SCRIPT_ERR_SIG_DER);
}		}

		if ((flags & SCRIPT_VERIFY_LOW_S) && !CPubKey::CheckLowS(sig)) {
return set_error(serror, SCRIPT_ERR_SIG_HIGH_S);		return set_error(serror, SCRIPT_ERR_SIG_HIGH_S);
}		}

bool CheckSignatureEncoding(const valtype &vchSig, uint32_t flags,		return true;
		}

		bool CheckTransactionSignatureEncoding(const valtype &vchSig, uint32_t flags,
ScriptError *serror) {		ScriptError *serror) {
// Empty signature. Not strictly DER encoded, but allowed to provide a		// Empty signature. Not strictly DER encoded, but allowed to provide a
// compact way to provide an invalid signature for use with CHECK(MULTI)SIG		// compact way to provide an invalid signature for use with CHECK(MULTI)SIG
if (vchSig.size() == 0) {		if (vchSig.size() == 0) {
return true;		return true;
}		}
if ((flags & (SCRIPT_VERIFY_DERSIG \| SCRIPT_VERIFY_LOW_S \|
SCRIPT_VERIFY_STRICTENC)) != 0 &&		if (!CheckSignatureWithoutSigHashTypeEncoding(
!IsValidSignatureEncoding(		vchSig \| boost::adaptors::sliced(0, vchSig.size() - 1), flags,
vchSig \| boost::adaptors::sliced(0, vchSig.size() - 1))) {		serror)) {
return set_error(serror, SCRIPT_ERR_SIG_DER);
}
if ((flags & SCRIPT_VERIFY_LOW_S) != 0 &&
!IsLowDERSignature(vchSig, serror)) {
// serror is set		// serror is set
return false;		return false;
}		}

if ((flags & SCRIPT_VERIFY_STRICTENC) != 0) {		if ((flags & SCRIPT_VERIFY_STRICTENC) != 0) {
if (!GetHashType(vchSig).isDefined()) {		if (!GetHashType(vchSig).isDefined()) {
return set_error(serror, SCRIPT_ERR_SIG_HASHTYPE);		return set_error(serror, SCRIPT_ERR_SIG_HASHTYPE);
}		}
bool usesForkId = GetHashType(vchSig).hasForkId();		bool usesForkId = GetHashType(vchSig).hasForkId();
bool forkIdEnabled = flags & SCRIPT_ENABLE_SIGHASH_FORKID;		bool forkIdEnabled = flags & SCRIPT_ENABLE_SIGHASH_FORKID;
if (!forkIdEnabled && usesForkId) {		if (!forkIdEnabled && usesForkId) {
return set_error(serror, SCRIPT_ERR_ILLEGAL_FORKID);		return set_error(serror, SCRIPT_ERR_ILLEGAL_FORKID);
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