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support.py
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from log import log
from decimal import Decimal
from config import TIMING_MEASURE, DEBUG
## timing decorator
def timing_log(func):
"""decoration for timing calculation"""
if TIMING_MEASURE:
import timeit
def get_timing(self, *args, **kwargs):
_begin = timeit.default_timer()
result = func(self, *args, **kwargs)
duration = timeit.default_timer() - _begin
d = Decimal(str(duration)).quantize(Decimal("0.001"), rounding = "ROUND_HALF_UP")
d_str = f"time: {d} sec"
print(f"{func.__name__} takes {d_str} seconds\n")
return result, d_str
return get_timing
else:
pass
## debug_decorator
def debug_control(func):
"""decoration for debug stuff"""
if DEBUG:
def do_debug_stuff(self, *args, **kwargs):
func(self, *args, **kwargs)
pass
return do_debug_stuff
else:
pass
# https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-56Cr2.pdf
# pip install bitstring if not
# https://bitstring.readthedocs.io/en/latest/walkthrough.html
def show_detail(m:str):
print(f"str = {m}, type(str) = {type(m)}, bytelen(str) = {len(m)}")
def NIST_KDM(Z:bytes, L: int, FixedInfo:bytes) -> int:
"""Key Derivate Method NIST.SP.800-56Cr2
Using option1 (no salt), Using hash256
return big uint
"""
assert L>0, f"Privided L value {L} is invalid, must be >0"
log('w', f"This function is not yet been tested!!!")
from bitstring import Bits
from hash_lib import hash_256
H_outputBits = 256 # given we use hash256
max_H_inputBits = 512-56 # restric input length to one hash
reps = int(L / H_outputBits) # L shall not exceed H_outputBits × (2^32 –1).
if reps > ( 1<<32 -1 ):
print( f"given L value is too big that up(L/256): {reps} > (2^32-1)")
return 0
c = Bits('uint:32=0')
z_enc = bytes(Z, encoding="utf-8")
z = Bits(bytes=z_enc)
f_enc = bytes(FixedInfo, encoding="utf-8")
f = Bits(bytes=f_enc)
concat= c + z + f
#.append(counter).append(z).append(f)
if len(concat) > max_H_inputBits:
print("error, concat string byte len ={len} > max_H_inputBits {max_H_inputBits}")
return 0
R = Bits(0)
i = 1
while i <= reps:
c_int = c.uint + 1
concat = Bits(uint=c_int, length=32) + z + f
concat_bytes = concat.bytes
K = hash_256(concat_bytes, msg_fmt = 'bytes')
R = R + Bits(uint=K, length=K.bit_length())
i += 1
msb = len(R) - 1
lsb = len(R) - L
result = R[lsb:msb].uint
return result
def SM2_KDF(Z, klen: int, dgest_type = 'sha256', input_fmt = 'str', return_fmt = 'hex'):
"""key derivation function of SM2 spec. 5.4.3"""
assert input_fmt == 'str' or input_fmt == 'bytes', f"not supported input format = {input_fmt}"
# assert return_fmt == 'hex' or return_fmt == 'bytes' or return_fmt == 'bits', f"not supported return format = {return_fmt}"
assert return_fmt == 'hex' or return_fmt == 'bits', f"not supported return format = {return_fmt}"
v = 256 # digest bit length
assert klen < (pow(2, 32) - 1 )*v
last_nbit = klen % v
if (klen % 8) != 0 and return_fmt == 'hex':
assert False, f"given (klen % 8) = {(klen % 4)}, but requested return format = {return_fmt}"
from bitstring import Bits
import hash_lib as hash
import struct
if input_fmt == 'str':
Z_byte = bytes(Z, encoding='UTF-8') # convert Z string to byte
else:
Z_byte = bytes.fromhex(Z)
n = klen // v
if last_nbit == 0:
n_iter = n
else:
n_iter = n + 1
# print(f"n_iter= {n_iter}, last_nbit = {last_nbit}")
# print(f"Z_byte= {Z_byte}")
ct=int(0x1) # init count (int32)
dgst = []
for i in range(n_iter):
ct_byte = struct.pack('>L', ct) # pack ct to byte (>: big Endian, L: unsigned long)
msg_byte = Z_byte + ct_byte # concatenate Z_byte and ct_byte
dgst_i = hash.hash_256(msg_byte, 'bytes', 'bytes', dgest_type)
# print(f"msg_byte= {msg_byte}")
# print(f"dgst[{i}] in hex = {dgst_i.hex()}")
if i == n_iter-1 and last_nbit: # the very last iteration
if return_fmt == 'hex':
last_nbyte = last_nbit // 8
dgst.append ( dgst_i[0:last_nbyte] )
elif return_fmt == 'bits':
temp_dgst = Bits( bytes = dgst_i)
last_bits = temp_dgst[0:last_nbit]
# dgst.append (last_dgst.bytes)
# print(f"The last iter: #{i}, last_nbit = {last_nbit}")
else:
dgst.append ( dgst_i )
last_bits = ''
ct = ct+1
len_ = len(dgst)
K_bytes = b''
for l in range (len_):
K_bytes = K_bytes + dgst[l]
# print(f"K_bytes = {K_bytes}")
if return_fmt == 'hex':
#K_bits = Bits( bytes= K_bytes )
return K_bytes.hex()
else:
K_bits = Bits( bytes= K_bytes ) + last_bits
return K_bits
if __name__ == '__main__':
log('i', "KDF function test:")
# test vector from sm3 spec. Part4, P8
# 坐标x 2 ：
# 64D20D27 D0632957 F8028C1E 024F6B02 EDF23102 A566C932 AE8BD613 A8E865FE
# 坐标y 2 ：
# 58D225EC A784AE30 0A81A2D4 8281A828 E1CEDF11 C4219099 84026537 5077BF78
# 消息M 的比特长度klen=152
# 计算t=KDF (x 2 ∥y 2 , klen)：
# 006E30 DAE231B0 71DFAD8A A379E902 64491603
x2 = '64D20D27D0632957F8028C1E024F6B02EDF23102A566C932AE8BD613A8E865FE'
y2 = '58D225ECA784AE300A81A2D48281A828E1CEDF11C4219099840265375077BF78'
#Z = bytes.fromhex (x2) + bytes.fromhex (y2)
#Z = bytes.fromhex (x2)[::-1] + bytes.fromhex (y2)[::-1] # Endian convert
klen = 152
Z = x2 + y2
t = SM2_KDF(Z, klen, 'sm3', 'bytes', 'hex')
log('i', f"klen = {klen}")
log('i', f"K = {t}")
klen = 150
t = SM2_KDF(Z, klen, 'sm3', 'bytes', 'bits')
log('i', f"klen = {klen}")
log('i', f"K = {t}")