def verify(self, rawdata, signature):
try:
binary_sign = base64.b64decode(signature)
except binasciiError:
return False
blocks = split(rawdata.encode(), BLOCK_SIZE)
signature_blocks = split(binary_sign, 256)
verified_block = []
for raw_block, sign_block in zip(blocks, signature_blocks):
c = int.from_bytes(sign_block, 'big')
original = pow(c, self.e, self.n)
signed = _int2Bytes(original)
verified_block.append(signed)
assembled = assemble(verified_block)
return assembled == bytes(rawdata.encode())
def sign(self, rawdata):
# Compute a fixed-length hash, so we don't have to deal with padding
blocks = split(rawdata.encode(), BLOCK_SIZE)
result = []
for b in blocks:
raw = int.from_bytes(b, 'big')
sign = pow(raw, self.d, self.n)
signature_chunk = _int2Bytes(sign)
result.append(signature_chunk)
representable = base64.b64encode(b"".join(result))
return representable
def test_long_word(self):
rawdata = bytes(randomword(30).encode())
blocks = split(rawdata, 15)
self.assertEqual(assemble(blocks), rawdata)
self.assertNotEqual(assemble(blocks[:-1]), rawdata)
def test_resplit(self):
rawdata = b"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
blocks = split(rawdata, 5)
self.assertEqual([b"ABCDE", b"FGHIJ", b"KLMNO", b"PQRST", b"UVWXY", b"Z\0\4\0\0"], blocks)
def test_split(self):
rawdata = b"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
blocks = split(rawdata, 16)
self.assertEqual(b"ABCDEFGHIJKLMNOP", blocks[0])
self.assertEqual(b"QRSTUVWXYZ\0\6\0\0\0\0", blocks[1])
def test_no_padd(self):
rawdata = bytes(randomword(30).encode())
blocks = split(rawdata, 10)
self.assertEqual(assemble(blocks), rawdata)
def test_all_word(self):
for i in range(1, 2 ** 10):
rawdata = bytes(randomword(i).encode())
blocks = split(rawdata, 15)
self.assertEqual(assemble(blocks), rawdata)