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Replace NOP2 with CHECKLOCKTIMEVERIFY
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<nLockTime> CHECKLOCKTIMEVERIFY -> <nLockTime>

Fails if tx.nLockTime < nLockTime, allowing the funds in a txout to be
locked until some block height or block time in the future is reached.

Only the logic and unittests are implemented; this commit does not have
any actual soft-fork logic in it.

Credit goes to Gregory Maxwell for the suggestion of comparing the
argument against the transaction nLockTime rather than the current
time/blockheight directly.
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@petertodd
petertodd committed Sep 29, 2014
1 parent b49b972 commit ab0f54f
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Showing 5 changed files with 181 additions and 1 deletion.
72 changes: 71 additions & 1 deletion src/script/interpreter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -217,7 +217,77 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, co
// Control
//
case OP_NOP:
case OP_NOP1: case OP_NOP2: case OP_NOP3: case OP_NOP4: case OP_NOP5:
case OP_NOP1:
break;
case OP_NOP2:
{
// CHECKLOCKTIMEVERIFY
//
// (nLockTime -- nLockTime )

if (!(flags & SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY))
break; // not enabled; treat as a NOP

if (stack.size() < 1)
return false;

// Note that elsewhere numeric opcodes are limited to
// operands in the range -2**31+1 to 2**31-1, however it is
// legal for opcodes to produce results exceeding that
// range. This limitation is implemented by CScriptNum's
// default 4-byte limit.
//
// If we kept to that limit we'd have a year 2038 problem,
// even though the nLockTime field in transactions
// themselves is uint32 which only becomes meaningless
// after the year 2106.
//
// Thus as a special case we tell CScriptNum to accept up
// to 5-byte bignums, which are good until 2**32-1, the
// same limit as the nLockTime field itself.
const CScriptNum nLockTime(stacktop(-1), 5);

// In the rare event that the argument may be < 0 due to
// some arithmetic being done first, you can always use
// 0 MAX CHECKLOCKTIMEVERIFY.
if (nLockTime < 0)
return false;

// There are two times of nLockTime: lock-by-blockheight
// and lock-by-blocktime, distinguished by whether
// nLockTime < LOCKTIME_THRESHOLD.
//
// We want to compare apples to apples, so fail the script
// unless the type of nLockTime being tested is the same as
// the nLockTime in the transaction.
if (!(
(txTo.nLockTime < LOCKTIME_THRESHOLD && nLockTime < LOCKTIME_THRESHOLD) ||
(txTo.nLockTime >= LOCKTIME_THRESHOLD && nLockTime >= LOCKTIME_THRESHOLD)
))
return false;

// Now that we know we're comparing apples-to-apples, the
// comparison is a simple numeric one.
if (nLockTime > (int64_t)txTo.nLockTime)
return false;

// Finally the nLockTime feature can be disabled and thus
// CHECKLOCKTIMEVERIFY bypassed if every txin has been
// finalized by setting nSequence to maxint. The
// transaction would be allowed into the blockchain, making
// the opcode ineffective.
//
// Testing if this vin is not final is sufficient to
// prevent this condition. Alternatively we could test all
// inputs, but testing just this input minimizes the data
// required to prove correct CHECKLOCKTIMEVERIFY execution.
if (txTo.vin[nIn].IsFinal())
return false;

break;

}
case OP_NOP3: case OP_NOP4: case OP_NOP5:
case OP_NOP6: case OP_NOP7: case OP_NOP8: case OP_NOP9: case OP_NOP10:
break;

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1 change: 1 addition & 0 deletions src/script/interpreter.h
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,7 @@ enum
SCRIPT_VERIFY_LOW_S = (1U << 2), // enforce low S values (<n/2) in signatures (depends on STRICTENC)
SCRIPT_VERIFY_NOCACHE = (1U << 3), // do not store results in signature cache (but do query it)
SCRIPT_VERIFY_NULLDUMMY = (1U << 4), // verify dummy stack item consumed by CHECKMULTISIG is of zero-length
SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY = (1U << 5), // support CHECKLOCKTIMEVERIFY opcode
};

bool IsCanonicalPubKey(const std::vector<unsigned char> &vchPubKey, unsigned int flags);
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66 changes: 66 additions & 0 deletions src/test/data/tx_invalid.json
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Original file line number Diff line number Diff line change
Expand Up @@ -103,5 +103,71 @@
[[["ad503f72c18df5801ee64d76090afe4c607fb2b822e9b7b63c5826c50e22fc3b", 0, "0x21 0x027c3a97665bf283a102a587a62a30a0c102d4d3b141015e2cae6f64e2543113e5 CHECKSIG NOT"]],

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@NEEDSBENTLEY

NEEDSBENTLEY Aug 3, 2017

ad503f72c18df5801ee64d76090afe4c607fb2b822e9b7b63c5826c50e22fc3b", 0, "0x21 0x027c3a97665bf283a102a587a62a30a0c102d4d3b141015e2cae6f64e2543113e5 CHECKSIG NOT"]],

Write

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@NEEDSBENTLEY

NEEDSBENTLEY Aug 3, 2017

i hope this is correct
"01000000013bfc220ec526583cb6b7e922b8b27f604cfe0a09764de61e80f58dc1723f50ad0000000000ffffffff0101000000000000002321027c3a97665bf283a102a587a62a30a0c102d4d3b141015e2cae6f64e2543113e5ac00000000", "P2SH"],

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@bigboss978

bigboss978 May 19, 2021

src/test/data/tx_valid.json

["CHECKLOCKTIMEVERIFY tests"],

["By-height locks, with argument just beyond tx nLockTime"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "1 NOP2 1"]],
"010000000100010000000000000000000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000", "P2SH,CHECKLOCKTIMEVERIFY"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "499999999 NOP2 1"]],
"0100000001000100000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000fe64cd1d", "P2SH,CHECKLOCKTIMEVERIFY"],

["By-time locks, with argument just beyond tx nLockTime (but within numerical boundries)"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "500000001 NOP2 1"]],
"01000000010001000000000000000000000000000000000000000000000000000000000000000000000000000000010000000000000000000065cd1d", "P2SH,CHECKLOCKTIMEVERIFY"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "4294967295 NOP2 1"]],
"0100000001000100000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000feffffff", "P2SH,CHECKLOCKTIMEVERIFY"],

["Argument missing"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "NOP2 1"]],
"010000000100010000000000000000000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000", "P2SH,CHECKLOCKTIMEVERIFY"],

["Argument negative with by-blockheight nLockTime=0"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "-1 NOP2 1"]],
"010000000100010000000000000000000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000", "P2SH,CHECKLOCKTIMEVERIFY"],

["Argument negative with by-blocktime nLockTime=500,000,000"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "-1 NOP2 1"]],
"01000000010001000000000000000000000000000000000000000000000000000000000000000000000000000000010000000000000000000065cd1d", "P2SH,CHECKLOCKTIMEVERIFY"],

["Input locked"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "0 NOP2 1"]],
"010000000100010000000000000000000000000000000000000000000000000000000000000000000000ffffffff0100000000000000000000000000", "P2SH,CHECKLOCKTIMEVERIFY"],

["Another input being unlocked isn't sufficient; the CHECKLOCKTIMEVERIFY-using input must be unlocked"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "0 NOP2 1"] ,
["0000000000000000000000000000000000000000000000000000000000000200", 1, "1"]],
"010000000200010000000000000000000000000000000000000000000000000000000000000000000000ffffffff00020000000000000000000000000000000000000000000000000000000000000100000000000000000100000000000000000000000000", "P2SH,CHECKLOCKTIMEVERIFY"],

["Argument/tx height/time mismatch, both versions"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "0 NOP2 1"]],
"01000000010001000000000000000000000000000000000000000000000000000000000000000000000000000000010000000000000000000065cd1d", "P2SH,CHECKLOCKTIMEVERIFY"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "499999999 NOP2 1"]],
"01000000010001000000000000000000000000000000000000000000000000000000000000000000000000000000010000000000000000000065cd1d", "P2SH,CHECKLOCKTIMEVERIFY"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "500000000 NOP2 1"]],
"010000000100010000000000000000000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000", "P2SH,CHECKLOCKTIMEVERIFY"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "500000000 NOP2 1"]],
"0100000001000100000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000ff64cd1d", "P2SH,CHECKLOCKTIMEVERIFY"],

["Argument 2^32 with nLockTime=2^32-1"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "4294967296 NOP2 1"]],
"0100000001000100000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000ffffffff", "P2SH,CHECKLOCKTIMEVERIFY"],

["Same, but with nLockTime=2^31-1"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "2147483648 NOP2 1"]],
"0100000001000100000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000ffffff7f", "P2SH,CHECKLOCKTIMEVERIFY"],

["6 byte non-minimally-encoded arguments are invalid even in their contents are valid"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "0x06 0x000000000000 NOP2 1"]],
"010000000100010000000000000000000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000", "P2SH,CHECKLOCKTIMEVERIFY"],

["Failure due to failing CHECKLOCKTIMEVERIFY in scriptSig"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "1"]],
"01000000010001000000000000000000000000000000000000000000000000000000000000000000000251b1000000000100000000000000000000000000", "P2SH,CHECKLOCKTIMEVERIFY"],

["Failure due to failing CHECKLOCKTIMEVERIFY in redeemScript"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "HASH160 0x14 0xc5b93064159b3b2d6ab506a41b1f50463771b988 EQUAL"]],
"0100000001000100000000000000000000000000000000000000000000000000000000000000000000030251b1000000000100000000000000000000000000", "P2SH,CHECKLOCKTIMEVERIFY"],

["Make diffs cleaner by leaving a comment here without comma at the end"]
]
42 changes: 42 additions & 0 deletions src/test/data/tx_valid.json
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Original file line number Diff line number Diff line change
Expand Up @@ -178,5 +178,47 @@
"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", "P2SH"],


["CHECKLOCKTIMEVERIFY tests"],

["By-height locks, with argument == 0 and == tx nLockTime"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "0 NOP2 1"]],
"010000000100010000000000000000000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000", "P2SH,CHECKLOCKTIMEVERIFY"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "499999999 NOP2 1"]],
"0100000001000100000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000ff64cd1d", "P2SH,CHECKLOCKTIMEVERIFY"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "0 NOP2 1"]],
"0100000001000100000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000ff64cd1d", "P2SH,CHECKLOCKTIMEVERIFY"],

["By-time locks, with argument just beyond tx nLockTime (but within numerical boundries)"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "500000000 NOP2 1"]],
"01000000010001000000000000000000000000000000000000000000000000000000000000000000000000000000010000000000000000000065cd1d", "P2SH,CHECKLOCKTIMEVERIFY"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "4294967295 NOP2 1"]],
"0100000001000100000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000ffffffff", "P2SH,CHECKLOCKTIMEVERIFY"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "500000000 NOP2 1"]],
"0100000001000100000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000ffffffff", "P2SH,CHECKLOCKTIMEVERIFY"],

["Any non-maxint nSequence is fine"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "0 NOP2 1"]],
"010000000100010000000000000000000000000000000000000000000000000000000000000000000000feffffff0100000000000000000000000000", "P2SH,CHECKLOCKTIMEVERIFY"],

["The argument can be calculated rather than created directly by a PUSHDATA"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "499999999 1ADD NOP2 1"]],
"01000000010001000000000000000000000000000000000000000000000000000000000000000000000000000000010000000000000000000065cd1d", "P2SH,CHECKLOCKTIMEVERIFY"],

["Perhaps even by an ADD producing a 5-byte result that is out of bounds for other opcodes"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "2147483647 2147483647 ADD NOP2 1"]],
"0100000001000100000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000feffffff", "P2SH,CHECKLOCKTIMEVERIFY"],

["5 byte non-minimally-encoded arguments are valid"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "0x05 0x0000000000 NOP2 1"]],
"010000000100010000000000000000000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000", "P2SH,CHECKLOCKTIMEVERIFY"],

["Valid CHECKLOCKTIMEVERIFY in scriptSig"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "1"]],
"01000000010001000000000000000000000000000000000000000000000000000000000000000000000251b1000000000100000000000000000001000000", "P2SH,CHECKLOCKTIMEVERIFY"],

["Valid CHECKLOCKTIMEVERIFY in redeemScript"],
[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "HASH160 0x14 0xc5b93064159b3b2d6ab506a41b1f50463771b988 EQUAL"]],
"0100000001000100000000000000000000000000000000000000000000000000000000000000000000030251b1000000000100000000000000000001000000", "P2SH,CHECKLOCKTIMEVERIFY"],

["Make diffs cleaner by leaving a comment here without comma at the end"]
]
1 change: 1 addition & 0 deletions src/test/transaction_tests.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,7 @@ unsigned int ParseScriptFlags(string strFlags){
mapFlagNames["STRICTENC"] = SCRIPT_VERIFY_STRICTENC;
mapFlagNames["LOW_S"] = SCRIPT_VERIFY_LOW_S;
mapFlagNames["NULLDUMMY"] = SCRIPT_VERIFY_NULLDUMMY;
mapFlagNames["CHECKLOCKTIMEVERIFY"] = SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY;
}

BOOST_FOREACH(string word, words)
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