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| import string
plaintext = "11101010"
K = "0111111101"
rounds = 2
alphabet = string.ascii_uppercase
def bin_to_ascii_4bit(bin_string):
h1, h2 = split_half(bin_string)
return alphabet[bin_to_int(h1)] + alphabet[bin_to_int(h2)]
def P10(data):
box = [3, 5, 2, 7, 4, 10, 1, 9, 8, 6]
return "".join(list(map(lambda x: data[x - 1], box)))
def P8(data):
box = [6, 3, 7, 4, 8, 5, 10, 9]
return "".join(list(map(lambda x: data[x - 1], box)))
def P4(data):
box = [2, 4, 3, 1]
return "".join(list(map(lambda x: data[x - 1], box)))
def S0(data):
row = bin_to_int(data[0] + data[3])
col = bin_to_int(data[1] + data[2])
box = [ ["01", "00" ,"11", "10"],
["11", "10", "01", "00"],
["00", "10", "01", "11"],
["11", "01", "11", "10"]
]
return box[row][col]
def S1(data):
row = bin_to_int(data[0] + data[3])
col = bin_to_int(data[1] + data[2])
box = [ ["00", "01", "10", "11"],
["10", "00", "01", "11"],
["11", "00", "01", "00"],
["10", "01", "00", "11"]
]
return box[row][col]
def IP(data):
box = [2, 6, 3, 1, 4, 8, 5, 7]
return "".join(list(map(lambda x: data[x - 1], box)))
def IP_1(data):
box = [4, 1, 3, 5, 7, 2, 8, 6]
return "".join(list(map(lambda x: data[x - 1], box)))
def E_P(data):
box = [4, 1, 2, 3, 2, 3, 4, 1]
return "".join(list(map(lambda x: data[x - 1], box)))
def XOR(data, key):
return "".join(list(map(lambda x, y: str(int(x) ^ int(y)), data, key)))
def LS(data, amount):
return data[amount:] + data[:amount]
def SW(data):
data1, data2 = split_half(data)
return data2 + data1
def split_half(data):
return data[:int(len(data) / 2)], data[int(len(data) / 2):]
def int_to_bin(data):
return "{0:b}".format(data)
def bin_to_int(data):
return int(data, 2)
def generate_round_keys(key, rounds):
round_keys = []
k_h1, k_h2 = split_half(P10(key))
s = 0
for i in range(1, rounds + 1):
s += i
h1, h2 = LS(k_h1, s), LS(k_h2, s)
round_keys.append(P8(h1 + h2))
return round_keys
def encrypt(data, key):
round_keys = generate_round_keys(key, rounds)
ip1, ip2 = split_half(IP(data))
print("IP: {}".format(ip1 + ip2))
for i, r_key in enumerate(round_keys):
data = E_P(ip2)
data = XOR(data, r_key)
d1, d2 = split_half(data)
d1 = S0(d1)
d2 = S1(d2)
data = XOR(ip1, P4(d1 + d2)) + ip2
if i == 0:
print("First Fk: {}".format(data))
elif i == 1:
print("Second Fk: {}".format(data))
if i != len(round_keys) - 1:
ip1, ip2 = split_half(SW(data))
print("SW: {}".format(ip1 + ip2))
else:
ciphertext = IP_1(data)
print("IP-1: {}".format(ciphertext))
return ciphertext
def decrypt(data, key, comments=False):
round_keys = list(reversed(generate_round_keys(key, rounds)))
ip1, ip2 = split_half(IP(data))
if comments:
print("IP: {}".format(ip1 + ip2))
for i, r_key in enumerate(round_keys):
data = E_P(ip2)
data = XOR(data, r_key)
d1, d2 = split_half(data)
d1 = S0(d1)
d2 = S1(d2)
data = XOR(ip1, P4(d1 + d2)) + ip2
if comments and i == 0:
print("First Fk: {}".format(data))
elif comments and i == 1:
print("Second Fk: {}".format(data))
if i != len(round_keys) - 1:
ip1, ip2 = split_half(SW(data))
if comments:
print("SW: {}".format(ip1 + ip2))
else:
plaintext = IP_1(data)
if comments:
print("IP-1: {}".format(plaintext))
return plaintext
if __name__ == "__main__":
print("需要加密的明文为: {} ({})".format(plaintext, bin_to_ascii_4bit(plaintext)))
print("Key: {}".format(K))
print("\n以下是加密的过程\n-------------------\n")
C= encrypt(plaintext,K)
print("加密后的密文为: {} ({})".format(C, bin_to_ascii_4bit(C)))
print("\n以下是解密的过程\n-------------------\n")
d = decrypt(C, K, comments=True)
print("解密后的明文是: {} ({})".format(d, bin_to_ascii_4bit(d)))
|
