def swapnibbleinbytes(data):
r"""
Performs a bit-reversal within a byte-string.
Example:
>>> swapbits(b'\xf0')
b'\x0f'
"""
return b"".join(SWAPBITSINBYTES_CACHE[b] for b in iterateints(data))
def transform_int_high(self, data):
# special case for re-encoding high part of offsets
# LiveMaker always only outputs 0 or 0xffffffff depending on if high
# bit ends up set
key = next(self.keystream)
data = [(b ^ ((key >> (8 * i)) & 0xff))
for i, b in enumerate(construct.iterateints(data))]
if data[3] & 0x80:
data = [0xff, 0xff, 0xff, 0xff]
else:
data = [0, 0, 0, 0]
return construct.integers2bytes(data)
def transform_int(self, data):
key = next(self.keystream)
data = [(b ^ ((key >> (8 * i)) & 0xff))
for i, b in enumerate(construct.iterateints(data))]
return construct.integers2bytes(data)
def transform_bytes(self, data):
return construct.integers2bytes((b ^ (next(self.keystream) & 0xff))
for b in construct.iterateints(data))