def test_reverse_engineering(self):
c = GenericCRC(polynomial="16_standard",
start_value=False,
final_xor=False,
reverse_polynomial=False,
reverse_all=False,
lsb_first=False,
little_endian=False)
bitstring_set = [
"1110001111001011100010000101010100000010110111000101100010100100111110111101100110110111011001010010001011101010",
"1110010011001011100010000101010100000010110111000101100010100100111110111101100110110111011001010010001011101010",
"1110010111001011100010000101010100000010110111000101100010100100111110111101100110110111011001010010001011101010",
"1110011011001011100010000101010100000010110111000101100010100100111110111101100110110111011001010010001011101010"
]
bitset = []
crcset = []
for i in bitstring_set:
tmp = c.str2bit(i)
bitset.append(tmp)
crcset.append(c.crc(tmp))
polynomial = c.reverse_engineer_polynomial(bitset, crcset)
if polynomial:
self.assertEqual(c.bit2str(polynomial), "1000000000000101")
self.assertEqual(util.bit2hex(polynomial), "8005")
def test_not_aligned_data_len(self):
c = GenericCRC(polynomial="16_standard", start_value=False, final_xor=False,
reverse_polynomial=False, reverse_all=False, lsb_first=False, little_endian=False)
polynomials = ["8_standard", "16_standard", "16_ccitt", "16_dnp"]
crcs = {"8_standard": 0xd5, "16_standard": 0x8005, "16_ccitt": 0x1021, "16_dnp": 0x3d65}
for j in polynomials:
c.polynomial = c.choose_polynomial(j)
inpt = "1"
for i in range(0, 32):
val = c.bit2int(c.crc(c.str2bit(inpt)))
self.assertEqual(val, crcs[j])
inpt = "0" + inpt
def test_reverse_engineering(self):
c = GenericCRC(polynomial="16_standard", start_value=False, final_xor=False,
reverse_polynomial=False, reverse_all=False, lsb_first=False, little_endian=False)
bitstring_set = [
"1110001111001011100010000101010100000010110111000101100010100100111110111101100110110111011001010010001011101010",
"1110010011001011100010000101010100000010110111000101100010100100111110111101100110110111011001010010001011101010",
"1110010111001011100010000101010100000010110111000101100010100100111110111101100110110111011001010010001011101010",
"1110011011001011100010000101010100000010110111000101100010100100111110111101100110110111011001010010001011101010"]
bitset = []
crcset = []
for i in bitstring_set:
tmp = c.str2bit(i)
bitset.append(tmp)
crcset.append(c.crc(tmp))
# print(c.guess_standard_parameters(bitset[0], crcset[0]))
polynomial = c.reverse_engineer_polynomial(bitset, crcset)
if polynomial:
self.assertEqual(c.bit2str(polynomial), "1000000000000101")
self.assertEqual(util.bit2hex(polynomial), "8005")
def test_different_crcs(self):
c = GenericCRC(polynomial="16_standard",
start_value=False,
final_xor=False,
reverse_polynomial=False,
reverse_all=False,
lsb_first=False,
little_endian=False)
bitstring_set = [
"101001001010101010101011101111111000000000000111101010011101011",
"101001001010101101111010110111101010010110111010",
"00000000000000000000000000000000100000000000000000000000000000000001111111111111",
"1111111111111111111111111111111110111111111111111111110111111111111111110000000000"
"1"
]
for j in c.DEFAULT_POLYNOMIALS:
c.polynomial = c.choose_polynomial(j)
for i in bitstring_set:
# Standard
crc_new = c.crc(c.str2bit(i))
crc_old = c.reference_crc(c.str2bit(i))
self.assertEqual(crc_new, crc_old)
# Special final xor
c.final_xor = c.str2bit("0000111100001111")
crc_new = c.crc(c.str2bit(i))
crc_old = c.reference_crc(c.str2bit(i))
self.assertEqual(crc_new, crc_old)
c.final_xor = [False] * 16
# Special start value
c.start_value = c.str2bit("1010101010101010")
crc_new = c.crc(c.str2bit(i))
crc_old = c.reference_crc(c.str2bit(i))
self.assertEqual(crc_new, crc_old)
c.start_value = [False] * 16
# reverse_polynomial
c.reverse_polynomial = True
crc_new = c.crc(c.str2bit(i))
crc_old = c.reference_crc(c.str2bit(i))
self.assertEqual(crc_new, crc_old)
c.reverse_polynomial = False
# lsb_first
c.lsb_first = True
crc_new = c.crc(c.str2bit(i))
crc_old = c.reference_crc(c.str2bit(i))
self.assertEqual(crc_new, crc_old)
c.lsb_first = False
# little_endian
c.little_endian = True
crc_new = c.crc(c.str2bit(i))
crc_old = c.reference_crc(c.str2bit(i))
self.assertEqual(crc_new, crc_old)
c.little_endian = False
# reverse all
c.reverse_all = True
crc_new = c.crc(c.str2bit(i))
crc_old = c.reference_crc(c.str2bit(i))
self.assertEqual(crc_new, crc_old)
c.reverse_all = False
def test_different_crcs_fast(self):
c = GenericCRC(polynomial="16_standard",
start_value=False,
final_xor=False,
reverse_polynomial=False,
reverse_all=False,
lsb_first=False,
little_endian=False)
bitstring_set = [
"10101010", "00000001", "000000010", "000000011",
"0000000100000001",
"101001001010101010101011101111111000000000000111101010011101011",
"101001001010101101111010110111101010010110111010",
"00000000000000000000000000000000100000000000000000000000000000000001111111111111",
"1111111111111111111111111111111110111111111111111111110111111111111111110000000000"
"1"
]
for j in c.DEFAULT_POLYNOMIALS:
c.polynomial = c.choose_polynomial(j)
for i in bitstring_set:
for cache in [8, 4, 7, 12, 16]:
c.calculate_cache(cache)
# Standard
crc_new = c.cached_crc(c.str2bit(i))
crc_old = c.reference_crc(c.str2bit(i))
self.assertEqual(crc_old, crc_new)
# Special final xor
c.final_xor = c.str2bit("0000111100001111")
crc_new = c.cached_crc(c.str2bit(i))
crc_old = c.reference_crc(c.str2bit(i))
self.assertEqual(crc_old, crc_new)
c.final_xor = [False] * 16
# Special start value
c.start_value = c.str2bit("1010101010101010")
crc_new = c.cached_crc(c.str2bit(i))
crc_old = c.reference_crc(c.str2bit(i))
self.assertEqual(crc_old, crc_new)
c.start_value = [False] * 16
# little_endian
c.little_endian = True
crc_new = c.cached_crc(c.str2bit(i))
crc_old = c.reference_crc(c.str2bit(i))
self.assertEqual(crc_old, crc_new)
c.little_endian = False
# reverse all
c.reverse_all = True
crc_new = c.cached_crc(c.str2bit(i))
crc_old = c.reference_crc(c.str2bit(i))
self.assertEqual(crc_old, crc_new)
c.reverse_all = False
# reverse_polynomial
# We need to clear the cache before and after
c.cache = []
#
c.reverse_polynomial = True
crc_new = c.cached_crc(c.str2bit(i))
crc_old = c.reference_crc(c.str2bit(i))
self.assertEqual(crc_old, crc_new)
c.reverse_polynomial = False
#
c.cache = []
# TODO: Does only work for cachesize = 8
# lsb_first
c.calculate_cache(8)
c.lsb_first = True
crc_new = c.cached_crc(c.str2bit(i))
crc_old = c.reference_crc(c.str2bit(i))
self.assertEqual(crc_old, crc_new)
c.lsb_first = False