From 98b135f97f16005687f420136114f80555bc8688 Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Sat, 8 Nov 2014 09:32:29 -0800 Subject: [PATCH 1/2] Make STRICTENC invalid pubkeys fail the script rather than the opcode. This turns STRICTENC turn into a softforking-safe change (even though it is not intended as a consensus rule), and as a result guarantee that using it for mempool validation only results in consensus-valid transactions in the mempool. --- src/script/interpreter.cpp | 12 ++++++------ src/script/interpreter.h | 4 ++-- src/script/script_error.cpp | 2 ++ src/script/script_error.h | 1 + src/test/data/script_invalid.json | 18 ++++++++++++++++++ src/test/data/script_valid.json | 18 +++++++++--------- src/test/script_tests.cpp | 21 +++++++++++++++------ 7 files changed, 53 insertions(+), 23 deletions(-) diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp index 760086eab..a2a2edce6 100644 --- a/src/script/interpreter.cpp +++ b/src/script/interpreter.cpp @@ -207,9 +207,9 @@ bool static CheckSignatureEncoding(const valtype &vchSig, unsigned int flags, Sc return true; } -bool static CheckPubKeyEncoding(const valtype &vchSig, unsigned int flags) { +bool static CheckPubKeyEncoding(const valtype &vchSig, unsigned int flags, ScriptError* serror) { if ((flags & SCRIPT_VERIFY_STRICTENC) != 0 && !IsCompressedOrUncompressedPubKey(vchSig)) { - return false; + return set_error(serror, SCRIPT_ERR_PUBKEYTYPE); } return true; } @@ -792,11 +792,11 @@ bool EvalScript(vector >& stack, const CScript& script, un // Drop the signature, since there's no way for a signature to sign itself scriptCode.FindAndDelete(CScript(vchSig)); - if (!CheckSignatureEncoding(vchSig, flags, serror)) { + if (!CheckSignatureEncoding(vchSig, flags, serror) || !CheckPubKeyEncoding(vchPubKey, flags, serror)) { //serror is set return false; } - bool fSuccess = CheckPubKeyEncoding(vchPubKey, flags) && checker.CheckSig(vchSig, vchPubKey, scriptCode); + bool fSuccess = checker.CheckSig(vchSig, vchPubKey, scriptCode); popstack(stack); popstack(stack); @@ -855,13 +855,13 @@ bool EvalScript(vector >& stack, const CScript& script, un valtype& vchSig = stacktop(-isig); valtype& vchPubKey = stacktop(-ikey); - if (!CheckSignatureEncoding(vchSig, flags, serror)) { + if (!CheckSignatureEncoding(vchSig, flags, serror) || !CheckPubKeyEncoding(vchPubKey, flags, serror)) { // serror is set return false; } // Check signature - bool fOk = CheckPubKeyEncoding(vchPubKey, flags) && checker.CheckSig(vchSig, vchPubKey, scriptCode); + bool fOk = checker.CheckSig(vchSig, vchPubKey, scriptCode); if (fOk) { isig++; diff --git a/src/script/interpreter.h b/src/script/interpreter.h index 12b271941..35b2f6c65 100644 --- a/src/script/interpreter.h +++ b/src/script/interpreter.h @@ -35,8 +35,8 @@ enum SCRIPT_VERIFY_P2SH = (1U << 0), // Passing a non-strict-DER signature or one with undefined hashtype to a checksig operation causes script failure. - // Passing a pubkey that is not (0x04 + 64 bytes) or (0x02 or 0x03 + 32 bytes) to checksig causes that pubkey to be - // skipped (not softfork safe: this flag can widen the validity of OP_CHECKSIG OP_NOT). + // Evaluating a pubkey that is not (0x04 + 64 bytes) or (0x02 or 0x03 + 32 bytes) by checksig causes script failure. + // (softfork safe, but not used or intended as a consensus rule). SCRIPT_VERIFY_STRICTENC = (1U << 1), // Passing a non-strict-DER signature to a checksig operation causes script failure (softfork safe, BIP62 rule 1) diff --git a/src/script/script_error.cpp b/src/script/script_error.cpp index 793fc0da4..5d24ed98b 100644 --- a/src/script/script_error.cpp +++ b/src/script/script_error.cpp @@ -61,6 +61,8 @@ const char* ScriptErrorString(const ScriptError serror) return "Dummy CHECKMULTISIG argument must be zero"; case SCRIPT_ERR_DISCOURAGE_UPGRADABLE_NOPS: return "NOPx reserved for soft-fork upgrades"; + case SCRIPT_ERR_PUBKEYTYPE: + return "Public key is neither compressed or uncompressed"; case SCRIPT_ERR_UNKNOWN_ERROR: case SCRIPT_ERR_ERROR_COUNT: default: break; diff --git a/src/script/script_error.h b/src/script/script_error.h index 21153f1bd..ac1f2deae 100644 --- a/src/script/script_error.h +++ b/src/script/script_error.h @@ -42,6 +42,7 @@ typedef enum ScriptError_t SCRIPT_ERR_SIG_PUSHONLY, SCRIPT_ERR_SIG_HIGH_S, SCRIPT_ERR_SIG_NULLDUMMY, + SCRIPT_ERR_PUBKEYTYPE, /* softfork safeness */ SCRIPT_ERR_DISCOURAGE_UPGRADABLE_NOPS, diff --git a/src/test/data/script_invalid.json b/src/test/data/script_invalid.json index 0356d0be1..96ff0a291 100644 --- a/src/test/data/script_invalid.json +++ b/src/test/data/script_invalid.json @@ -592,6 +592,24 @@ nSequences are max. "", "P2PK NOT with hybrid pubkey but no STRICTENC" ], +[ + "0x47 0x3044022078033e4227aa05ded69d8da579966578e230d8a7fb44d5f1a0620c3853c24f78022006a2e3f4d872ac8dfdc529110aa37301d65a76255a4b6cce2992adacd4d2c4e201", + "0x41 0x0679be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8 CHECKSIG NOT", + "STRICTENC", + "P2PK NOT with hybrid pubkey" +], +[ + "0x47 0x304402207592427de20e315d644839754f2a5cca5b978b983a15e6da82109ede01722baa022032ceaf78590faa3f7743821e1b47b897ed1a57f6ee1c8a7519d23774d8de3c4401", + "0x41 0x0679be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8 CHECKSIG NOT", + "STRICTENC", + "P2PK NOT with invalid hybrid pubkey" +], +[ + "0 0x47 0x304402206797289d3dc81692edae58430276d04641ea5d86967be557163f8494da32fd78022006fc6ab77aaed4ac11ea69cd878ab26e3e24290f47a43e9adf34075d52b7142c01", + "1 0x21 0x038282263212c609d9ea2a6e3e172de238d8c39cabd5ac1ca10646e23fd5f51508 0x41 0x0679be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8 2 CHECKMULTISIG", + "STRICTENC", + "1-of-2 with the first 1 hybrid pubkey" +], [ "0x47 0x304402201f82b99a813c9c48c8dee8d2c43b8f637b72353fe9bdcc084537bc17e2ab770402200c43b96a5f7e115f0114eabda32e068145965cb6c7b5ef64833bb4fcf9fc1b3b05", "0x41 0x048282263212c609d9ea2a6e3e172de238d8c39cabd5ac1ca10646e23fd5f5150811f8a8098557dfe45e8256e830b60ace62d613ac2f7b17bed31b6eaff6e26caf CHECKSIG", diff --git a/src/test/data/script_valid.json b/src/test/data/script_valid.json index 0cf156316..94e1abfaa 100644 --- a/src/test/data/script_valid.json +++ b/src/test/data/script_valid.json @@ -743,12 +743,6 @@ nSequences are max. "", "P2PK with hybrid pubkey but no STRICTENC" ], -[ - "0x47 0x3044022078033e4227aa05ded69d8da579966578e230d8a7fb44d5f1a0620c3853c24f78022006a2e3f4d872ac8dfdc529110aa37301d65a76255a4b6cce2992adacd4d2c4e201", - "0x41 0x0679be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8 CHECKSIG NOT", - "STRICTENC", - "P2PK NOT with hybrid pubkey" -], [ "0x47 0x3044022078d6c447887e88dcbe1bc5b613645280df6f4e5935648bc226e9d91da71b3216022047d6b7ef0949b228fc1b359afb8d50500268711354298217b983c26970790c7601", "0x41 0x0679be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8 CHECKSIG NOT", @@ -756,10 +750,16 @@ nSequences are max. "P2PK NOT with invalid hybrid pubkey but no STRICTENC" ], [ - "0x47 0x304402207592427de20e315d644839754f2a5cca5b978b983a15e6da82109ede01722baa022032ceaf78590faa3f7743821e1b47b897ed1a57f6ee1c8a7519d23774d8de3c4401", - "0x41 0x0679be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8 CHECKSIG NOT", + "0 0x47 0x304402203b269b9fbc0936877bf855b5fb41757218d9548b246370d991442a5f5bd1c3440220235268a4eaa8c67e543c6e37da81dd36d3b1be2de6b4fef04113389ca6ddc04501", + "1 0x41 0x0679be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8 0x21 0x038282263212c609d9ea2a6e3e172de238d8c39cabd5ac1ca10646e23fd5f51508 2 CHECKMULTISIG", + "", + "1-of-2 with the second 1 hybrid pubkey and no STRICTENC" +], +[ + "0 0x47 0x3044022044dc17b0887c161bb67ba9635bf758735bdde503e4b0a0987f587f14a4e1143d022009a215772d49a85dae40d8ca03955af26ad3978a0ff965faa12915e9586249a501", + "1 0x41 0x0679be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798483ada7726a3c4655da4fbfc0e1108a8fd17b448a68554199c47d08ffb10d4b8 0x21 0x038282263212c609d9ea2a6e3e172de238d8c39cabd5ac1ca10646e23fd5f51508 2 CHECKMULTISIG", "STRICTENC", - "P2PK NOT with invalid hybrid pubkey" + "1-of-2 with the second 1 hybrid pubkey" ], [ "0x47 0x304402204649e9517ef0377a8f8270bd423053fd98ddff62d74ea553e9579558abbb75e4022044a2b2344469c12e35ed898987711272b634733dd0f5e051288eceb04bd4669e05", diff --git a/src/test/script_tests.cpp b/src/test/script_tests.cpp index 36aaa6903..6952f4c58 100644 --- a/src/test/script_tests.cpp +++ b/src/test/script_tests.cpp @@ -428,15 +428,24 @@ BOOST_AUTO_TEST_CASE(script_build) bad.push_back(TestBuilder(CScript() << ToByteVector(keys.pubkey0H) << OP_CHECKSIG << OP_NOT, "P2PK NOT with hybrid pubkey but no STRICTENC", 0 ).PushSig(keys.key0, SIGHASH_ALL)); - good.push_back(TestBuilder(CScript() << ToByteVector(keys.pubkey0H) << OP_CHECKSIG << OP_NOT, - "P2PK NOT with hybrid pubkey", SCRIPT_VERIFY_STRICTENC - ).PushSig(keys.key0, SIGHASH_ALL)); + bad.push_back(TestBuilder(CScript() << ToByteVector(keys.pubkey0H) << OP_CHECKSIG << OP_NOT, + "P2PK NOT with hybrid pubkey", SCRIPT_VERIFY_STRICTENC + ).PushSig(keys.key0, SIGHASH_ALL)); good.push_back(TestBuilder(CScript() << ToByteVector(keys.pubkey0H) << OP_CHECKSIG << OP_NOT, "P2PK NOT with invalid hybrid pubkey but no STRICTENC", 0 ).PushSig(keys.key0, SIGHASH_ALL).DamagePush(10)); - good.push_back(TestBuilder(CScript() << ToByteVector(keys.pubkey0H) << OP_CHECKSIG << OP_NOT, - "P2PK NOT with invalid hybrid pubkey", SCRIPT_VERIFY_STRICTENC - ).PushSig(keys.key0, SIGHASH_ALL).DamagePush(10)); + bad.push_back(TestBuilder(CScript() << ToByteVector(keys.pubkey0H) << OP_CHECKSIG << OP_NOT, + "P2PK NOT with invalid hybrid pubkey", SCRIPT_VERIFY_STRICTENC + ).PushSig(keys.key0, SIGHASH_ALL).DamagePush(10)); + good.push_back(TestBuilder(CScript() << OP_1 << ToByteVector(keys.pubkey0H) << ToByteVector(keys.pubkey1C) << OP_2 << OP_CHECKMULTISIG, + "1-of-2 with the second 1 hybrid pubkey and no STRICTENC", 0 + ).Num(0).PushSig(keys.key1, SIGHASH_ALL)); + good.push_back(TestBuilder(CScript() << OP_1 << ToByteVector(keys.pubkey0H) << ToByteVector(keys.pubkey1C) << OP_2 << OP_CHECKMULTISIG, + "1-of-2 with the second 1 hybrid pubkey", SCRIPT_VERIFY_STRICTENC + ).Num(0).PushSig(keys.key1, SIGHASH_ALL)); + bad.push_back(TestBuilder(CScript() << OP_1 << ToByteVector(keys.pubkey1C) << ToByteVector(keys.pubkey0H) << OP_2 << OP_CHECKMULTISIG, + "1-of-2 with the first 1 hybrid pubkey", SCRIPT_VERIFY_STRICTENC + ).Num(0).PushSig(keys.key1, SIGHASH_ALL)); good.push_back(TestBuilder(CScript() << ToByteVector(keys.pubkey1) << OP_CHECKSIG, "P2PK with undefined hashtype but no STRICTENC", 0 From ca8158719b17ebdcf1de1e26079b6b896122d0e5 Mon Sep 17 00:00:00 2001 From: Peter Todd Date: Mon, 10 Nov 2014 02:33:19 -0500 Subject: [PATCH 2/2] Test the exact order of CHECKMULTISIG sig/pubkey evaluation Possible with STRICTENC --- src/script/interpreter.cpp | 6 +++++- src/test/data/script_invalid.json | 19 +++++++++++++++++++ src/test/data/script_valid.json | 25 +++++++++++++++++++++++++ 3 files changed, 49 insertions(+), 1 deletion(-) diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp index a2a2edce6..5eda23731 100644 --- a/src/script/interpreter.cpp +++ b/src/script/interpreter.cpp @@ -855,6 +855,9 @@ bool EvalScript(vector >& stack, const CScript& script, un valtype& vchSig = stacktop(-isig); valtype& vchPubKey = stacktop(-ikey); + // Note how this makes the exact order of pubkey/signature evaluation + // distinguishable by CHECKMULTISIG NOT if the STRICTENC flag is set. + // See the script_(in)valid tests for details. if (!CheckSignatureEncoding(vchSig, flags, serror) || !CheckPubKeyEncoding(vchPubKey, flags, serror)) { // serror is set return false; @@ -871,7 +874,8 @@ bool EvalScript(vector >& stack, const CScript& script, un nKeysCount--; // If there are more signatures left than keys left, - // then too many signatures have failed + // then too many signatures have failed. Exit early, + // without checking any further signatures. if (nSigsCount > nKeysCount) fSuccess = false; } diff --git a/src/test/data/script_invalid.json b/src/test/data/script_invalid.json index 96ff0a291..71e757714 100644 --- a/src/test/data/script_invalid.json +++ b/src/test/data/script_invalid.json @@ -616,6 +616,25 @@ nSequences are max. "STRICTENC", "P2PK with undefined hashtype" ], + +[" +Order of CHECKMULTISIG evaluation tests, inverted by swapping the order of +pubkeys/signatures so they fail due to the STRICTENC rules on validly encoded +signatures and pubkeys. +"], +[ + "0 0x47 0x3044022044dc17b0887c161bb67ba9635bf758735bdde503e4b0a0987f587f14a4e1143d022009a215772d49a85dae40d8ca03955af26ad3978a0ff965faa12915e9586249a501 0x47 0x3044022044dc17b0887c161bb67ba9635bf758735bdde503e4b0a0987f587f14a4e1143d022009a215772d49a85dae40d8ca03955af26ad3978a0ff965faa12915e9586249a501", + "2 0x21 0x02865c40293a680cb9c020e7b1e106d8c1916d3cef99aa431a56d253e69256dac0 0 2 CHECKMULTISIG NOT", + "STRICTENC", + "2-of-2 CHECKMULTISIG NOT with the first pubkey invalid, and both signatures validly encoded." +], +[ + "0 0x47 0x3044022044dc17b0887c161bb67ba9635bf758735bdde503e4b0a0987f587f14a4e1143d022009a215772d49a85dae40d8ca03955af26ad3978a0ff965faa12915e9586249a501 0", + "2 0x21 0x02865c40293a680cb9c020e7b1e106d8c1916d3cef99aa431a56d253e69256dac0 0x21 0x02865c40293a680cb9c020e7b1e106d8c1916d3cef99aa431a56d253e69256dac0 2 CHECKMULTISIG NOT", + "STRICTENC", + "2-of-2 CHECKMULTISIG NOT with both pubkeys valid, but first signature invalid." +], + [ "0x47 0x30440220166848cd5b82a32b5944d90de3c35249354b43773c2ece1844ee8d1103e2f6c602203b6b046da4243c77adef80ada9201b27bbfdf7f9d5428f40434b060432afd62005", "0x41 0x048282263212c609d9ea2a6e3e172de238d8c39cabd5ac1ca10646e23fd5f5150811f8a8098557dfe45e8256e830b60ace62d613ac2f7b17bed31b6eaff6e26caf CHECKSIG NOT", diff --git a/src/test/data/script_valid.json b/src/test/data/script_valid.json index 94e1abfaa..ada45a64e 100644 --- a/src/test/data/script_valid.json +++ b/src/test/data/script_valid.json @@ -761,6 +761,31 @@ nSequences are max. "STRICTENC", "1-of-2 with the second 1 hybrid pubkey" ], + +[" +CHECKMULTISIG evaluation order tests. CHECKMULTISIG evaluates signatures and +pubkeys in a specific order, and will exit early if the number of signatures +left to check is greater than the number of keys left. As STRICTENC fails the +script when it reaches an invalidly encoded signature or pubkey, we can use it +to test the exact order in which signatures and pubkeys are evaluated by +distinguishing CHECKMULTISIG returning false on the stack and the script as a +whole failing. + +See also the corresponding inverted versions of these tests in script_invalid.json +"], +[ + "0 0x47 0x3044022044dc17b0887c161bb67ba9635bf758735bdde503e4b0a0987f587f14a4e1143d022009a215772d49a85dae40d8ca03955af26ad3978a0ff965faa12915e9586249a501 0x47 0x3044022044dc17b0887c161bb67ba9635bf758735bdde503e4b0a0987f587f14a4e1143d022009a215772d49a85dae40d8ca03955af26ad3978a0ff965faa12915e9586249a501", + "2 0 0x21 0x02865c40293a680cb9c020e7b1e106d8c1916d3cef99aa431a56d253e69256dac0 2 CHECKMULTISIG NOT", + "STRICTENC", + "2-of-2 CHECKMULTISIG NOT with the second pubkey invalid, and both signatures validly encoded. Valid pubkey fails, and CHECKMULTISIG exits early, prior to evaluation of second invalid pubkey." +], +[ + "0 0 0x47 0x3044022044dc17b0887c161bb67ba9635bf758735bdde503e4b0a0987f587f14a4e1143d022009a215772d49a85dae40d8ca03955af26ad3978a0ff965faa12915e9586249a501", + "2 0x21 0x02865c40293a680cb9c020e7b1e106d8c1916d3cef99aa431a56d253e69256dac0 0x21 0x02865c40293a680cb9c020e7b1e106d8c1916d3cef99aa431a56d253e69256dac0 2 CHECKMULTISIG NOT", + "STRICTENC", + "2-of-2 CHECKMULTISIG NOT with both pubkeys valid, but second signature invalid. Valid pubkey fails, and CHECKMULTISIG exits early, prior to evaluation of second invalid signature." +], + [ "0x47 0x304402204649e9517ef0377a8f8270bd423053fd98ddff62d74ea553e9579558abbb75e4022044a2b2344469c12e35ed898987711272b634733dd0f5e051288eceb04bd4669e05", "0x41 0x048282263212c609d9ea2a6e3e172de238d8c39cabd5ac1ca10646e23fd5f5150811f8a8098557dfe45e8256e830b60ace62d613ac2f7b17bed31b6eaff6e26caf CHECKSIG",