python - 用python编写hmac_sha1算法

Question

在Python编程范围内，我尝试用Python编写hmac-sha1函数。代码如下所示。但返回的值似乎不是正确的值。

计算的 HMAC:cb1e45d7fb852695e63731edb4f58547f9249ad9

值必须是:de7c9b85b8b78aa6bc8a7a36f70a90701c9db4d9

我的代码中是否有任何错误以及如何修复它以获得预期值。

谢谢

#HMAC

import hashlib


toHex = lambda x:"".join([hex(ord(c))[2:].zfill(2) for c in x])  #return string

# initiate i_pad and o_pad
i_pad = int('36'*64,16)
o_pad = int('5C'*64,16)

def hmac(key,msg):
    print('key=',key,'msg=',msg)
    h_key = toHex(key)
    h_msg = int(toHex(msg),16)

    if len(h_key)>128:
        #hash key if len(key) > 64 bytes
        h_key = hashlib.sha1(h_key.encode('ascii'))
    while len(h_key)<128:
        # padding key to 64 bytes
        h_key+='00'

    h_key = (int(h_key,16))                  
    i_key_pad = h_key ^ i_pad
    o_key_pad = h_key ^ o_pad

    #first pass
    first_msg=hex(i_key_pad)[2:] + hex(h_msg)[2:]    
    hash1 = hashlib.sha1(first_msg.encode('ascii'))         
    #second pass
    second_msg = hex(o_key_pad)[2:] + hash1.hexdigest()
    hash2 = hashlib.sha1(second_msg.encode('ascii'))  
    return hash2.hexdigest()


def test():
    hash = hmac("key", "The quick brown fox jumps over the lazy dog")
    print('computed hmac',hash)
    print('value must be de7c9b85b8b78aa6bc8a7a36f70a90701c9db4d9')

test1()

Answer 1

我已经重写了字节代码，但结果仍然不正确!

from hashlib import sha1
import sys

def encrypt1(var, key):
    return bytes(a ^ b for a, b in zip(var, key))

#The second one uses int.from_bytes and int.to_bytes: 20 x faster
def encrypt2(var, key):
    key = key[:len(var)]
    int_var = int.from_bytes(var, sys.byteorder)
    int_key = int.from_bytes(key, sys.byteorder)
    int_enc = int_var ^ int_key
    return int_enc.to_bytes(len(var), sys.byteorder)

key, msg = b'key', b'The quick brown fox jumps over the lazy dog'
# initiate i_pad and o_pad
i_pad = b'6'*64   # chr(0x36)='6'
o_pad = b'\\'*64   # chr(0x5C)='\\'
print(i_pad)
print(o_pad)

key = key+b'0'*(64-len(key))
print(key,len(key))

i_key_pad = encrypt2(i_pad, key)
print(i_key_pad)

o_key_pad = encrypt2(o_pad, key)
print(o_key_pad)

#first pass
first_msg = i_key_pad + msg
print(first_msg, len(first_msg))
hash1 = sha1(first_msg)
#print(hash1.hexdigest())
print(hash1.digest())

#second pass
second_msg = o_key_pad + hash1.digest()
print(second_msg, len(second_msg))
hash2 = sha1(second_msg)
print(hash2.hexdigest())

print('de7c9b85b8b78aa6bc8a7a36f70a90701c9db4d9 expected')`