def disassemble_multisig(redeem_script):
# take apart a standard multisig's redeem/witness script, and return M/N and offset of
# one pubkey (if provided) involved
# - can only for multisig
# - expect OP_1 (pk1) (pk2) (pk3) OP_3 OP_CHECKMULTISIG for 1 of 3 case
# - returns M, N, (list of pubkeys)
from serializations import disassemble
M, N = -1, -1
# generator
dis = disassemble(redeem_script)
# expect M value first
M, opcode = next(dis)
assert opcode == None and isinstance(M, int), 'garbage at start'
pubkeys = []
for offset, (data, opcode) in enumerate(dis):
if opcode == OP_CHECKMULTISIG:
# should be last byte
break
if isinstance(data, int):
N = data
else:
pubkeys.append(data)
else:
raise AssertionError("end fall")
assert len(pubkeys) == N
assert 1 <= M <= N <= 20, 'M/N range' # will also happen if N not encoded.
return M, N, pubkeys
def disassemble_multisig(redeem_script):
# Take apart a standard multisig's redeem/witness script, and return M/N and public keys
# - only for multisig scripts, not general purpose
# - expect OP_1 (pk1) (pk2) (pk3) OP_3 OP_CHECKMULTISIG for 1 of 3 case
# - returns M, N, (list of pubkeys)
# - for very unlikely/impossible asserts, dont document reason; otherwise do.
from serializations import disassemble
M, N = disassemble_multisig_mn(redeem_script)
assert 1 <= M <= N <= MAX_SIGNERS, 'M/N range'
assert len(redeem_script) == 1 + (N * 34) + 1 + 1, 'bad len'
# generator function
dis = disassemble(redeem_script)
# expect M value first
ex_M, opcode = next(dis)
assert ex_M == M and opcode == None, 'bad M'
# need N pubkeys
pubkeys = []
for idx in range(N):
data, opcode = next(dis)
assert opcode == None and len(data) == 33, 'data'
assert data[0] == 0x02 or data[0] == 0x03, 'Y val'
pubkeys.append(data)
assert len(pubkeys) == N
# next is N value
ex_N, opcode = next(dis)
assert ex_N == N and opcode == None
# finally, the opcode: CHECKMULTISIG
data, opcode = next(dis)
assert opcode == OP_CHECKMULTISIG
# must have reached end of script at this point
try:
next(dis)
raise AssertionError("too long")
except StopIteration:
# expected, since we're reading past end
pass
return M, N, pubkeys