Make empty byte arrays pass CheckSignatureEncoding()

Makes it possible to compactly provide a delibrately invalid signature
for use with CHECK(MULTI)SIG. For instance with BIP19 if m != n invalid
signatures need to be provided in the scriptSig; prior to this change
those invalid signatures would need to be large DER-encoded signatures.

Note that we may want to further expand on this change in the future by
saying that only OP_0 is a "valid" invalid signature; BIP19 even with
this change is inherently malleable as the invalid signatures can be any
validly encoded DER signature.
This commit is contained in:
Peter Todd
2015-01-09 05:52:57 -05:00
parent d0c97bbe70
commit 2fa9a8ec86
4 changed files with 11 additions and 5 deletions

View File

@@ -504,7 +504,7 @@
"2-of-2 CHECKMULTISIG NOT with the first pubkey invalid, and both signatures validly encoded."
],
[
"0 0x47 0x3044022044dc17b0887c161bb67ba9635bf758735bdde503e4b0a0987f587f14a4e1143d022009a215772d49a85dae40d8ca03955af26ad3978a0ff965faa12915e9586249a501 0",
"0 0x47 0x3044022044dc17b0887c161bb67ba9635bf758735bdde503e4b0a0987f587f14a4e1143d022009a215772d49a85dae40d8ca03955af26ad3978a0ff965faa12915e9586249a501 1",
"2 0x21 0x02865c40293a680cb9c020e7b1e106d8c1916d3cef99aa431a56d253e69256dac0 0x21 0x02865c40293a680cb9c020e7b1e106d8c1916d3cef99aa431a56d253e69256dac0 2 CHECKMULTISIG NOT",
"STRICTENC",
"2-of-2 CHECKMULTISIG NOT with both pubkeys valid, but first signature invalid."

View File

@@ -662,6 +662,11 @@
["0 0 0x02 0x0000", "CHECKMULTISIGVERIFY 1", ""],
["0 0x02 0x0000 0", "CHECKMULTISIGVERIFY 1", ""],
["While not really correctly DER encoded, the empty signature is allowed by"],
["STRICTENC to provide a compact way to provide a delibrately invalid signature."],
["0", "0x21 0x02865c40293a680cb9c020e7b1e106d8c1916d3cef99aa431a56d253e69256dac0 CHECKSIG NOT", "STRICTENC"],
["0 0", "1 0x21 0x02865c40293a680cb9c020e7b1e106d8c1916d3cef99aa431a56d253e69256dac0 1 CHECKMULTISIG NOT", "STRICTENC"],
["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"],