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Add SCRIPT_VERIFY_MINIMALDATA (BIP62 rules 3 and 4)

Browse source 
Also use the new flag as a standard rule, and replace the IsCanonicalPush
standardness check with it (as it is more complete).
This commit is contained in:
Pieter Wuille 2014-10-08 18:48:59 -07:00
parent d752ba86c1
commit 698c6abb25
11 changed files with 101 additions and 59 deletions
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4
src/main.cpp
View file

@ -633,10 +633,6 @@ bool IsStandardTx(const CTransaction& tx, string& reason)
reason = "scriptsig-not-pushonly";
return false;
}
if (!txin.scriptSig.HasCanonicalPushes()) {
reason = "scriptsig-non-canonical-push";
return false;
}
}
unsigned int nDataOut = 0;

51
src/script/interpreter.cpp
View file

@ -157,6 +157,29 @@ bool static CheckPubKeyEncoding(const valtype &vchSig, unsigned int flags) {
return true;
}
bool static CheckMinimalPush(const valtype& data, opcodetype opcode) {
if (data.size() == 0) {
// Could have used OP_0.
return opcode == OP_0;
} else if (data.size() == 1 && data[0] >= 1 && data[0] <= 16) {
// Could have used OP_1 .. OP_16.
return opcode == OP_1 + (data[0] - 1);
} else if (data.size() == 1 && data[0] == 0x81) {
// Could have used OP_1NEGATE.
return opcode == OP_1NEGATE;
} else if (data.size() <= 75) {
// Could have used a direct push (opcode indicating number of bytes pushed + those bytes).
return opcode == data.size();
} else if (data.size() <= 255) {
// Could have used OP_PUSHDATA.
return opcode == OP_PUSHDATA1;
} else if (data.size() <= 65535) {
// Could have used OP_PUSHDATA2.
return opcode == OP_PUSHDATA2;
}
return true;
}
bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker)
{
CScript::const_iterator pc = script.begin();
@ -169,6 +192,7 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
if (script.size() > 10000)
return false;
int nOpCount = 0;
bool fRequireMinimal = (flags & SCRIPT_VERIFY_MINIMALDATA) != 0;
try
{
@ -205,9 +229,12 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
opcode == OP_RSHIFT)
return false; // Disabled opcodes.
if (fExec && 0 <= opcode && opcode <= OP_PUSHDATA4)
if (fExec && 0 <= opcode && opcode <= OP_PUSHDATA4) {
if (fRequireMinimal && !CheckMinimalPush(vchPushValue, opcode)) {
return false;
}
stack.push_back(vchPushValue);
else if (fExec || (OP_IF <= opcode && opcode <= OP_ENDIF))
} else if (fExec || (OP_IF <= opcode && opcode <= OP_ENDIF))
switch (opcode)
{
//
@ -234,6 +261,8 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
// ( -- value)
CScriptNum bn((int)opcode - (int)(OP_1 - 1));
stack.push_back(bn.getvch());
// The result of these opcodes should always be the minimal way to push the data
// they push, so no need for a CheckMinimalPush here.
}
break;
@ -458,7 +487,7 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
// (xn ... x2 x1 x0 n - ... x2 x1 x0 xn)
if (stack.size() < 2)
return false;
int n = CScriptNum(stacktop(-1)).getint();
int n = CScriptNum(stacktop(-1), fRequireMinimal).getint();
popstack(stack);
if (n < 0 || n >= (int)stack.size())
return false;
@ -557,7 +586,7 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
// (in -- out)
if (stack.size() < 1)
return false;
CScriptNum bn(stacktop(-1));
CScriptNum bn(stacktop(-1), fRequireMinimal);
switch (opcode)
{
case OP_1ADD: bn += bnOne; break;
@ -590,8 +619,8 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
// (x1 x2 -- out)
if (stack.size() < 2)
return false;
CScriptNum bn1(stacktop(-2));
CScriptNum bn2(stacktop(-1));
CScriptNum bn1(stacktop(-2), fRequireMinimal);
CScriptNum bn2(stacktop(-1), fRequireMinimal);
CScriptNum bn(0);
switch (opcode)
{
@ -635,9 +664,9 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
// (x min max -- out)
if (stack.size() < 3)
return false;
CScriptNum bn1(stacktop(-3));
CScriptNum bn2(stacktop(-2));
CScriptNum bn3(stacktop(-1));
CScriptNum bn1(stacktop(-3), fRequireMinimal);
CScriptNum bn2(stacktop(-2), fRequireMinimal);
CScriptNum bn3(stacktop(-1), fRequireMinimal);
bool fValue = (bn2 <= bn1 && bn1 < bn3);
popstack(stack);
popstack(stack);
@ -727,7 +756,7 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
if ((int)stack.size() < i)
return false;
int nKeysCount = CScriptNum(stacktop(-i)).getint();
int nKeysCount = CScriptNum(stacktop(-i), fRequireMinimal).getint();
if (nKeysCount < 0 || nKeysCount > 20)
return false;
nOpCount += nKeysCount;
@ -738,7 +767,7 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
if ((int)stack.size() < i)
return false;
int nSigsCount = CScriptNum(stacktop(-i)).getint();
int nSigsCount = CScriptNum(stacktop(-i), fRequireMinimal).getint();
if (nSigsCount < 0 || nSigsCount > nKeysCount)
return false;
int isig = ++i;

7
src/script/interpreter.h
View file

@ -49,6 +49,13 @@ enum
// Using a non-push operator in the scriptSig causes script failure (softfork safe, BIP62 rule 2).
SCRIPT_VERIFY_SIGPUSHONLY = (1U << 5),
// Require minimal encodings for all push operations (OP_0... OP_16, OP_1NEGATE where possible, direct
// pushes up to 75 bytes, OP_PUSHDATA up to 255 bytes, OP_PUSHDATA2 for anything larger). Evaluating
// any other push causes the script to fail (BIP62 rule 3).
// In addition, whenever a stack element is interpreted as a number, it must be of minimal length (BIP62 rule 4).
// (softfork safe)
SCRIPT_VERIFY_MINIMALDATA = (1U << 6)
};
uint256 SignatureHash(const CScript &scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType);

29
src/script/script.cpp
View file

@ -12,7 +12,7 @@ namespace {
inline std::string ValueString(const std::vector<unsigned char>& vch)
{
if (vch.size() <= 4)
return strprintf("%d", CScriptNum(vch).getint());
return strprintf("%d", CScriptNum(vch, false).getint());
else
return HexStr(vch);
}
@ -238,33 +238,6 @@ bool CScript::IsPushOnly() const
return true;
}
bool CScript::HasCanonicalPushes() const
{
const_iterator pc = begin();
while (pc < end())
{
opcodetype opcode;
std::vector<unsigned char> data;
if (!GetOp(pc, opcode, data))
return false;
if (opcode > OP_16)
continue;
if (opcode < OP_PUSHDATA1 && opcode > OP_0 && (data.size() == 1 && data[0] <= 16))
// Could have used an OP_n code, rather than a 1-byte push.
return false;
if (opcode == OP_PUSHDATA1 && data.size() < OP_PUSHDATA1)
// Could have used a normal n-byte push, rather than OP_PUSHDATA1.
return false;
if (opcode == OP_PUSHDATA2 && data.size() <= 0xFF)
// Could have used an OP_PUSHDATA1.
return false;
if (opcode == OP_PUSHDATA4 && data.size() <= 0xFFFF)
// Could have used an OP_PUSHDATA2.
return false;
}
return true;
}
std::string CScript::ToString() const
{
std::string str;

18
src/script/script.h
View file

@ -192,10 +192,14 @@ public:
m_value = n;
}
explicit CScriptNum(const std::vector<unsigned char>& vch)
explicit CScriptNum(const std::vector<unsigned char>& vch, bool fRequireMinimal)
{
if (vch.size() > nMaxNumSize)
throw scriptnum_error("CScriptNum(const std::vector<unsigned char>&) : overflow");
if (vch.size() > nMaxNumSize) {
throw scriptnum_error("script number overflow");
}
if (fRequireMinimal && vch.size() > 0 && (vch.back() & 0x7f) == 0 && (vch.size() <= 1 || (vch[vch.size() - 2] & 0x80) == 0)) {
throw scriptnum_error("non-minimally encoded script number");
}
m_value = set_vch(vch);
}
@ -319,7 +323,6 @@ private:
int64_t m_value;
};
/** Serialized script, used inside transaction inputs and outputs */
class CScript : public std::vector<unsigned char>
{
@ -330,6 +333,10 @@ protected:
{
push_back(n + (OP_1 - 1));
}
else if (n == 0)
{
push_back(OP_0);
}
else
{
*this << CScriptNum::serialize(n);
@ -554,9 +561,6 @@ public:
// Called by IsStandardTx and P2SH/BIP62 VerifyScript (which makes it consensus-critical).
bool IsPushOnly() const;
// Called by IsStandardTx.
bool HasCanonicalPushes() const;
// Returns whether the script is guaranteed to fail at execution,
// regardless of the initial stack. This allows outputs to be pruned
// instantly when entering the UTXO set.

1
src/script/standard.h
View file

@ -41,6 +41,7 @@ static const unsigned int MANDATORY_SCRIPT_VERIFY_FLAGS = SCRIPT_VERIFY_P2SH;
// blocks and we must accept those blocks.
static const unsigned int STANDARD_SCRIPT_VERIFY_FLAGS = MANDATORY_SCRIPT_VERIFY_FLAGS |
SCRIPT_VERIFY_STRICTENC |
SCRIPT_VERIFY_MINIMALDATA |
SCRIPT_VERIFY_NULLDUMMY;
// For convenience, standard but not mandatory verify flags.

4
src/test/data/script_invalid.json
View file

@ -384,6 +384,10 @@ nSequences are max.
["0x00", "'00' EQUAL", "P2SH,STRICTENC", "Basic OP_0 execution"],
["1 IF 0x01 0x81 ENDIF 1", "", "MINIMALDATA", "evaluated non-minimal data"],
["1 IF 0x01 0x05 ENDIF 1", "", "MINIMALDATA", "evaluated non-minimal data"],
["1 IF 0x4c 0x03 0x222222 ENDIF 1", "", "MINIMALDATA", "evaluated non-minimal data"],
[
"0x47 0x30440220304eff7556bba9560df47873275e64db45f3cd735998ce3f00d2e57b1bb5f31302205c0c9d14b8b80d43e2ac9b87532f1af6d8a3271262bc694ec4e14068392bb0a001",
"0x41 0x0479be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8 CHECKSIG",

31
src/test/data/script_valid.json
View file

@ -529,6 +529,33 @@ nSequences are max.
["0x00", "SIZE 0 EQUAL", "P2SH,STRICTENC", "Basic OP_0 execution"],
["0x01 0x81", "0x4f EQUAL", "", "direct push of 0x81 equals 1NEGATE"],
["0x01 0x05", "5 EQUAL", "", "direct push of 0x05 equals 5"],
["0x4c 0x4b 0x111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111", "0x4b 0x111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111 EQUAL", "", "PUSHDATA1 of 75 bytes equals direct push of it"],
["0x4d 0xFF00 0x111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111", "0x4c 0xFF 0x111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111 EQUAL", "", "PUSHDATA2 of 255 bytes equals PUSHDATA1 of it"],
["0x02 0x8000", "128 NUMEQUAL", "", "0x8000 equals 128"],
["0x01 0x00", "0 NUMEQUAL", "", "0x00 numequals 0"],
["0x01 0x80", "0 NUMEQUAL", "", "0x80 (negative zero) numequals 0"],
["0x02 0x0080", "0 NUMEQUAL", "", "0x0080 numequals 0"],
["0x02 0x0500", "5 NUMEQUAL", "", "0x0500 numequals 5"],
["0x03 0xff7f80", "0x02 0xffff NUMEQUAL", "", ""],
["0x03 0xff7f00", "0x02 0xff7f NUMEQUAL", "", ""],
["0x04 0xffff7f80", "0x03 0xffffff NUMEQUAL", "", ""],
["0x04 0xffff7f00", "0x03 0xffff7f NUMEQUAL", "", ""],
["0 IF 0x01 0x81 ENDIF 1", "", "MINIMALDATA", "unevaluated non-minimal data"],
["0 IF 0x01 0x05 ENDIF 1", "", "MINIMALDATA", "unevaluated non-minimal data"],
["0 IF 0x02 0x8000 ENDIF 1", "", "MINIMALDATA", "unevaluated non-minimal data"],
["0 IF 0x01 0x00 ENDIF 1", "", "MINIMALDATA", "unevaluated non-minimal data"],
["0 IF 0x01 0x80 ENDIF 1", "", "MINIMALDATA", "unevaluated non-minimal data"],
["0 IF 0x02 0x0080 ENDIF 1", "", "MINIMALDATA", "unevaluated non-minimal data"],
["0 IF 0x02 0x0400 ENDIF 1", "", "MINIMALDATA", "unevaluated non-minimal data"],
["0 IF 0x03 0xff7f80 ENDIF 1", "", "MINIMALDATA", "unevaluated non-minimal data"],
["0 IF 0x03 0xff7f00 ENDIF 1", "", "MINIMALDATA", "unevaluated non-minimal data"],
["0 IF 0x04 0xffff7f80 ENDIF 1", "", "MINIMALDATA", "unevaluated non-minimal data"],
["0 IF 0x04 0xffff7f00 ENDIF 1", "", "MINIMALDATA", "unevaluated non-minimal data"],
["0 IF 0x4c 0x03 0x222222 ENDIF 1", "", "MINIMALDATA", "unevaluated non-minimal data"],
[
"0x47 0x3044022007415aa37ce7eaa6146001ac8bdefca0ddcba0e37c5dc08c4ac99392124ebac802207d382307fd53f65778b07b9c63b6e196edeadf0be719130c5db21ff1e700d67501",
"0x41 0x0479be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8 CHECKSIG",
@ -638,13 +665,13 @@ nSequences are max.
"P2PK NOT with invalid sig and undefined hashtype but no STRICTENC"
],
[
"0x01 0x01 0x47 0x3044022046ce33d1771b0127dd4c4cef8fdc3218ebdfa60e3793ed700292d8ebd93fb1f402201029d47a414db83e96e31443c2d8b552f971469c4800f5eff7df2f0648521aed01 0x47 0x304402205c53911ad55b054920043962bbda98cf6e57e2db1cd5611138251490baabaa8702201dc80dfceae6007e7772dc13ff6e7ca66a983cb017fe5d46d30118462d83bcf801 0x47 0x304402201937e44a4ec12364f9d32f9d25e7ecbc68aee9ef90069af80efef4c05f6ace9602206c515101c00c75710b32ff7ff8dbaf7c9a0be6e86ed14a0755b47626604f31fd01",
"1 0x47 0x3044022046ce33d1771b0127dd4c4cef8fdc3218ebdfa60e3793ed700292d8ebd93fb1f402201029d47a414db83e96e31443c2d8b552f971469c4800f5eff7df2f0648521aed01 0x47 0x304402205c53911ad55b054920043962bbda98cf6e57e2db1cd5611138251490baabaa8702201dc80dfceae6007e7772dc13ff6e7ca66a983cb017fe5d46d30118462d83bcf801 0x47 0x304402201937e44a4ec12364f9d32f9d25e7ecbc68aee9ef90069af80efef4c05f6ace9602206c515101c00c75710b32ff7ff8dbaf7c9a0be6e86ed14a0755b47626604f31fd01",
"3 0x21 0x0279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798 0x21 0x038282263212c609d9ea2a6e3e172de238d8c39cabd5ac1ca10646e23fd5f51508 0x21 0x03363d90d447b00c9c99ceac05b6262ee053441c7e55552ffe526bad8f83ff4640 3 CHECKMULTISIG",
"",
"3-of-3 with nonzero dummy but no NULLDUMMY"
],
[
"0x01 0x01 0x47 0x30440220195038dbc6b2ae1199f86a6777824f7c5149789d85f655a3534a4422b8fba38c02204df9db87d2eb9fe06edc66870d9ac4c9ce673459f9d43cee0347ce4ffb02ee5a01 0x47 0x3044022010a45f30c6fa97a186eba9e6b595ab87d3dfcbf05dcaf1f1b8e3e7bf39515bb802203474e78d3d372e5f5c0f8c257ce8300c4bb8f37c51d4a894e11a91b5817da6ed01 0x47 0x30440220039cffd8e39850f95112662b1220b14b3c0d3d8a2772e13c947bfbf96345a64e02204154bfa77e2c0134d5434353bed82141e5da1cc479954aa288d5f0671480a04b01",
"1 0x47 0x30440220195038dbc6b2ae1199f86a6777824f7c5149789d85f655a3534a4422b8fba38c02204df9db87d2eb9fe06edc66870d9ac4c9ce673459f9d43cee0347ce4ffb02ee5a01 0x47 0x3044022010a45f30c6fa97a186eba9e6b595ab87d3dfcbf05dcaf1f1b8e3e7bf39515bb802203474e78d3d372e5f5c0f8c257ce8300c4bb8f37c51d4a894e11a91b5817da6ed01 0x47 0x30440220039cffd8e39850f95112662b1220b14b3c0d3d8a2772e13c947bfbf96345a64e02204154bfa77e2c0134d5434353bed82141e5da1cc479954aa288d5f0671480a04b01",
"3 0x21 0x0279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798 0x21 0x038282263212c609d9ea2a6e3e172de238d8c39cabd5ac1ca10646e23fd5f51508 0x21 0x03363d90d447b00c9c99ceac05b6262ee053441c7e55552ffe526bad8f83ff4640 3 CHECKMULTISIG NOT",
"",
"3-of-3 NOT with invalid sig and nonzero dummy but no NULLDUMMY"

10
src/test/script_tests.cpp
View file

@ -179,7 +179,7 @@ public:
TestBuilder& Num(int num)
{
DoPush();
spendTx.vin[0].scriptSig << CScriptNum(num);
spendTx.vin[0].scriptSig << num;
return *this;
}
@ -788,19 +788,19 @@ BOOST_AUTO_TEST_CASE(script_combineSigs)
BOOST_AUTO_TEST_CASE(script_standard_push)
{
for (int i=0; i<1000; i++) {
for (int i=0; i<67000; i++) {
CScript script;
script << i;
BOOST_CHECK_MESSAGE(script.IsPushOnly(), "Number " << i << " is not pure push.");
BOOST_CHECK_MESSAGE(script.HasCanonicalPushes(), "Number " << i << " push is not canonical.");
BOOST_CHECK_MESSAGE(VerifyScript(script, CScript() << OP_1, SCRIPT_VERIFY_MINIMALDATA, BaseSignatureChecker()), "Number " << i << " push is not minimal data.");
}
for (int i=0; i<1000; i++) {
for (unsigned int i=0; i<=MAX_SCRIPT_ELEMENT_SIZE; i++) {
std::vector<unsigned char> data(i, '\111');
CScript script;
script << data;
BOOST_CHECK_MESSAGE(script.IsPushOnly(), "Length " << i << " is not pure push.");
BOOST_CHECK_MESSAGE(script.HasCanonicalPushes(), "Length " << i << " push is not canonical.");
BOOST_CHECK_MESSAGE(VerifyScript(script, CScript() << OP_1, SCRIPT_VERIFY_MINIMALDATA, BaseSignatureChecker()), "Length " << i << " push is not minimal data.");
}
}

4
src/test/scriptnum_tests.cpp
View file

@ -25,11 +25,11 @@ static void CheckCreateVch(const int64_t& num)
BOOST_CHECK(verify(bignum, scriptnum));
CBigNum bignum2(bignum.getvch());
CScriptNum scriptnum2(scriptnum.getvch());
CScriptNum scriptnum2(scriptnum.getvch(), false);
BOOST_CHECK(verify(bignum2, scriptnum2));
CBigNum bignum3(scriptnum2.getvch());
CScriptNum scriptnum3(bignum2.getvch());
CScriptNum scriptnum3(bignum2.getvch(), false);
BOOST_CHECK(verify(bignum3, scriptnum3));
}

1
src/test/transaction_tests.cpp
View file

@ -34,6 +34,7 @@ static std::map<string, unsigned int> mapFlagNames = boost::assign::map_list_of
(string("DERSIG"), (unsigned int)SCRIPT_VERIFY_DERSIG)
(string("LOW_S"), (unsigned int)SCRIPT_VERIFY_LOW_S)
(string("SIGPUSHONLY"), (unsigned int)SCRIPT_VERIFY_SIGPUSHONLY)
(string("MINIMALDATA"), (unsigned int)SCRIPT_VERIFY_MINIMALDATA)
(string("NULLDUMMY"), (unsigned int)SCRIPT_VERIFY_NULLDUMMY);
unsigned int ParseScriptFlags(string strFlags)