OP_0 gives a zero length byte array because OP_0 == 0x00 which is equivalent to pushdata with zero length. OP_EQUAL compares byte strings as-is. So it will push "false" because empty string is not the same as a single-byte string with 0x00 byte in it. Value "false" in turn is encoded as empty string, just like result of OP_0. > On 06 Nov 2015, at 10:37, Tier Nolan via bitcoin-dev wrote: > > I meant not to use the OP_PUSH opcodes to do the push. > > Does OP_0 give a zero length byte array? > > Would this script return true? > > OP_0 > OP_PUSHDATA1 (length = 1, data = 0) > OP_EQUAL > > The easiest definition is that OP_0 and OP_1 must be used to push the data and not any other push opcodes. > > > On Fri, Nov 6, 2015 at 9:32 AM, Oleg Andreev > wrote: > > > One and zero should be defined as arrays of length one. Otherwise, it is still possible to mutate the transaction by changing the length of the array. > > > > They should also be minimally encoded but that is covered by previous rules. > > These two lines contradict each other. Minimally-encoded "zero" is an array of length zero, not one. I'd suggest defining this explicitly here as "IF/NOTIF argument must be either zero-length array or a single byte 0x01". > > > > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev