| 描述： |
```
# -- coding: utf-8 --
import hashlib,base64
def f(a,b):
digest = hashlib.sha256(a + b).digest()
return digest[:8]
def str_xor(a,b):
return ''.join( chr(ord(a[i]) ^ ord(b[i])) for i in range(len(a)))
def round_add(a, b):
res = str_xor(f(a,b),f(b,a))
return res
def permutate(table, block):
return list(map(lambda x: block[x], table))
def str_permutate(table, block):
t = map(lambda x: block[x], string_to_list(table))
return ''.join(chr(i) for i in t)
def string_to_bits(data):
data = [ord(c) for c in data]
l = len(data) 8
result = [0] l
pos = 0
for ch in data:
for i in range(0,8):
result[(pos<<3)+i] = (ch>>i) & 1
pos += 1
return result
def string_to_list(data):
a = []
a.extend(ord(i) for i in data)
return a
s_box = [55, 87, 54, 131, 139, 71, 3, 147, 34, 212, 231, 22, 170, 230, 154, 112, 81, 225, 218, 246, 227, 23, 8, 114, 65, 111, 189, 202, 136, 250, 179, 60, 177, 28, 166, 151, 50, 224, 25, 152, 221, 219, 242, 27, 115, 93, 208, 153, 35, 162, 30, 191, 105, 140, 129, 243, 245, 186, 132, 6, 41, 63, 254, 249, 165, 217, 49, 21, 210, 241, 159, 188, 44, 200, 37, 67, 144, 197, 205, 232, 211, 69, 80, 160, 252, 84, 76, 158, 173, 157, 204, 79, 62, 86, 237, 38, 171, 51, 17, 229, 148, 39, 43, 196, 103, 57, 142, 77, 155, 46, 45, 164, 91, 133, 16, 161, 141, 190, 47, 116, 26, 207, 61, 72, 137, 56, 104, 176, 2, 75, 123, 100, 236, 9, 180, 203, 183, 128, 13, 124, 89, 58, 83, 182, 201, 233, 175, 130, 122, 52, 138, 220, 29, 178, 213, 145, 113, 127, 174, 7, 167, 214, 146, 98, 48, 14, 194, 156, 42, 206, 110, 235, 238, 18, 4, 96, 228, 149, 0, 253, 101, 107, 119, 32, 117, 134, 92, 53, 193, 94, 90, 172, 143, 185, 244, 199, 109, 102, 15, 85, 11, 209, 251, 10, 163, 12, 120, 222, 255, 126, 226, 135, 40, 192, 150, 215, 240, 99, 1, 97, 64, 36, 248, 82, 234, 68, 70, 184, 125, 198, 31, 5, 73, 187, 118, 106, 239, 169, 74, 95, 24, 20, 223, 19, 33, 78, 216, 168, 108, 59, 88, 247, 195, 66, 181, 121]
def generate(o):
k = permutate(o,s_box)
b = []
for i in range(0, len(k), 7):
b.append(k[i:i+7] + [1])
c = []
for i in range(32):
pos = 0
x = 0
for j in b[i]:
x += (j<<pos)
pos += 1
c.append((0x10001x) % (0x7f))
return permutate(o,s_box)
class N1ES_2:
def __init__(self, key):
if len(key) != 32 :
raise Exception("key must be 32 bytes long")
self.key = key
self.gen_subkey()
def gen_subkey(self):
o = string_to_bits(self.key)
k = []
for i in range(8):
o = generate(o)
k.extend(o)
o = string_to_bits([chr(c) for c in o[0:32]])
self.Kn = []
for i in range(32):
t = map(chr, k[i 8: i 8 + 8])
self.Kn.append(''.join(i for i in t))
return
def encrypt(self, plaintext):
if (len(plaintext) % 16 != 0 or isinstance(plaintext, bytes) == False):
raise Exception("plaintext must be a multiple of 16 in length")
res = ''
for i in range(len(plaintext) / 16):
block = plaintext[i 16:(i + 1) 16]
L = block[:8]
R = block[8:]
for round_cnt in range(32):
L, R = R, str_xor(round_add(R, self.Kn[round_cnt]),L)
L, R = str_permutate(L,s_box) , str_permutate(R,s_box)
L, R = R, L
res += L + R
return res
key = "7056b257805ec2b8325795b0e6061f89"
n1es = N1ES_2(key)
cipher = n1es.encrypt(FLAG)
print base64.b64encode(cipher) # TZPvbvJQ8l2T7G5NmrlDWPLoymq2See29B16+/xf+qk=
```
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