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| def padding(src,num):
src = str(src)
src = '0'*(num-len(src))+src
return src
def xor(str1,str2):
res = []
for i in range(len(str1)):
if int(str1[i])==int(str2[i]):
res.append(0)
else:
res.append(1)
return res
def list_from_zero(list1):
new = []
for each in list1:
new.append(each-1)
return new
def bin2asc(list_of_bin):
group = [list_of_bin[8*i:8*i+8] for i in range(int(len(list_of_bin)/8))]
res = ''
for one in group:
temp = 0
for each in one:
temp*=2
temp+=int(each)
res+=chr(temp)
return res
def asc2bin(str1):
res = ''
for each in str1:
res+=padding(bin(ord(each))[2:],8)
return res
class DES:
def __init__(self,key):
self.key=''
key=key[0:8]
print("[*]key只取了8个字母扩展成bits,长于8个字母的key取了前八个字母!")
for i in key:
self.key+=padding(bin(ord(i))[2:],8)
self.p_box_left = list_from_zero([57,49,41,33,25,17,9,1,58,50,42,34,26,18,10,2,59,51,43,35,27,19,11,3,60,52,44,36])
self.p_box_right = list_from_zero([63,55,47,39,31,23,15,7,62,54,46,38,30,22,14,6,61,53,45,37,29,21,13,5,28,20,12,4])
self.key_left = [self.key[i] for i in self.p_box_left]
self.key_right = [self.key[i] for i in self.p_box_right]
self.s=[[14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7, 0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8, 4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0, 15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13]
,[15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10, 3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5, 0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15, 13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9]
,[10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8, 13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1, 13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7, 1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12]
,[7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15, 13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9, 10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4, 3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14]
,[2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9, 14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6, 4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14, 11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3]
,[12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11, 10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8, 9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6, 4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13]
,[4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1, 13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6, 1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2, 6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12]
,[13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7, 1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2, 7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8, 2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11]]
self.p = list_from_zero([58,50,42,34,26,18,10,2,60,52,44,36,28,20,12,4,
62,54,46,38,30,22,14,6,64,56,48,40,32,24,16,8,
57,49,41,33,25,17,9,1,59,51,43,35,27,19,11,3,
61,53,45,37,29,21,13,5,63,55,47,39,31,23,15,7])
self.p_rev = list_from_zero([40, 8, 48, 16, 56, 24, 64, 32, 39, 7, 47, 15, 55, 23, 63, 31,
38, 6, 46, 14, 54, 22, 62, 30, 37, 5, 45, 13, 53, 21, 61, 29,
36, 4, 44, 12, 52, 20, 60, 28, 35, 3, 43, 11, 51, 19, 59, 27,
34, 2, 42, 10, 50, 18, 58, 26, 33, 1, 41, 9, 49, 17, 57, 25])
self.roll_dict = {1:1,2:1,3:2,4:2,5:2,6:2,7:2,8:2,9:1,10:2,11:2,12:2,13:2,14:2,15:2,16:1}
self.yasuo = list_from_zero([14, 17, 11, 24, 1, 5, 3, 28, 15, 6, 21, 10
,23, 19, 12, 4, 26, 8, 16, 7, 27, 20, 13, 2
,41, 52, 31, 37, 47, 55, 30, 40, 51, 45, 33, 48
,44, 49, 39, 56, 34, 53, 46, 42, 50, 36, 29, 32])
self.p_box = list_from_zero([16, 7, 20, 21, 29, 12, 28, 17, 1, 15, 23, 26, 5, 18, 31, 10, 2, 8, 24, 14, 32, 27, 3, 9, 19, 13, 30, 6, 22, 11, 4, 25])
def IP_change(self,plain):
new_plain = [plain[i] for i in self.p]
return new_plain
def IP_rev(self,cypher):
new_cypher = [cypher[i] for i in self.p_rev]
return new_cypher
def key_gen(self,times):
roll_time = self.roll_dict[times]
for i in range(roll_time):
temp = self.key_left.pop(0)
self.key_left.append(temp)
temp = self.key_right.pop(0)
self.key_right.append(temp)
all_list = self.key_left+self.key_right
final = [all_list[i] for i in self.yasuo]
return final
def key_gen_decode(self,times):
roll_time = self.roll_dict[17-times]
all_list = self.key_left+self.key_right
final = [all_list[i] for i in self.yasuo]
for i in range(roll_time):
temp = self.key_left.pop(-1)
self.key_left.insert(0,temp)
temp = self.key_right.pop(-1)
self.key_right.insert(0,temp)
return final
def E_box(self,part):
first_list = [part[i*4:i*4+4] for i in range(8)]
second_list = []
for each in range(len(first_list)):
temp = first_list[each][:]
temp.insert(0,first_list[(each-1)%8][-1])
temp.append(first_list[(each+1)%8][0])
second_list += temp
return second_list
def S_box(self,part):
group = [part[6*i:6*i+6] for i in range(8)]
final = []
i=0
for each in group:
row = each[0]*2+each[5]
col = each[4]+each[3]*2+each[2]*4+each[1]*8
temp = padding(bin(self.s[i][row*16+col])[2:],4)
i+=1
for one in temp:
final.append(int(one))
return final
def P_box(self,part):
final = [part[i] for i in self.p_box]
return final
def decode_64bits(self,plain):
ipchange = self.IP_change(plain)
L = ipchange[0:32]
R = ipchange[32:]
for i in range(16):
extend = self.E_box(L[:])
key = self.key_gen_decode(i+1)
after_xor = xor(extend,key)
after_s = self.S_box(after_xor)
after_p = self.P_box(after_s)
final = xor(R,after_p)
R=L[:]
L = final[:]
res = ''.join([str(i) for i in self.IP_rev(L+R)])
return res
def encode_64bits(self,cypher):
ipchange = self.IP_change(cypher)
L = ipchange[0:32]
R = ipchange[32:]
for i in range(16):
temp = L[:]
L = R[:]
extend = self.E_box(R)
key = self.key_gen(i+1)
after_xor = xor(extend,key)
after_s = self.S_box(after_xor)
after_p = self.P_box(after_s)
final = xor(temp,after_p)
R = final[:]
res = ''.join([str(i) for i in self.IP_rev(L+R)])
return res
def analyse():
a=DES('DeS_KeY!')
str1='1000100101000100001101001000101110000101000000010001011100110000'
for each in range(len(str1)):
new = list(str1[:])
if new[each]=='1':
new[each]='0'
new=''.join(new)
res = a.decode_64bits(new)
print("第"+str(each+1)+"位明文改变了密文的:第",end='')
for sec in range(len(res)):
if res[sec]=='0':
print(str(sec+1),end=' ')
print("改变")
print()
else:
new[each]='1'
new=''.join(new)
res = a.decode_64bits(new)
print("第"+str(each+1)+"位明文改变了密文的:第",end='')
for sec in range(len(res)):
if res[sec]=='0':
print(str(sec+1),end=' ')
print("改变")
print()
if __name__=="__main__":
a=DES('DeS_KeY!')
print("plain:",'1101'*16)
temp = a.encode_64bits('1101'*16)
print("cypher:",temp)
print("decode",a.decode_64bits(temp))
|
需要注意的是,feistel是一种加密的框架,因为其中的f可以由用户自行定义,而且f对于解密不产生任何影响。提醒一点:解密的时候首先要把L和R反一下,一开始写des的时候解密就是因为最后没有注意到这里导致无法解密,最后手撸des的时候发现这一点才解决...
也就是原来的第58位放到第一位,第50位放到第二位balabala..
16轮迭代之后恰好为28,回到原点继续代下一个块
具体看下每个部分
具体的使用,举个栗子,假设第一个6bits为110101,取首位两个bits,即为11,为3对应第三行
中间1010为10对应第十列,第一个6bits对应S1那么就换成12,即1100
也就通过S盒完成了110101->1100的6bits到4bits的转换 列出8个S盒: S盒1:
14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7 0, 15, 7, 4, 14, 2,
13, 1, 10, 6, 12, 11, 9, 5, 3, 8 4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9,
7, 3, 10, 5, 0 15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13
S盒2: 15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10 3, 13, 4, 7,
15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5 0, 14, 7, 11, 10, 4, 13, 1, 5,
8, 12, 6, 9, 3, 2, 15 13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14,
9 S盒3: 10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8 13, 7, 0,
9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1 13, 6, 4, 9, 8, 15, 3, 0, 11,
1, 2, 12, 5, 10, 14, 7 1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2,
12 S盒4: 7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5 ,11, 12, 4, 15 13, 8, 11,
5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9 10, 6, 9, 0, 12, 11, 7, 13,
15, 1, 3, 14, 5, 2, 8, 4 3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7,
2, 14 S盒5: 2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9 14, 11,
2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6 4, 2, 1, 11, 10, 13, 7, 8,
15, 9, 12, 5, 6, 3, 0, 14 11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10,
4, 5, 3 S盒6: 12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11 10,
15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8 9, 14, 15, 5, 2, 8, 12,
3, 7, 0, 4, 10, 1, 13, 11, 6 4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6,
0, 8, 13 S盒7: 4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1 13,
0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6 1, 4, 11, 13, 12, 3, 7,
14, 10, 15, 6, 8, 0, 5, 9, 2 6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14,
2, 3, 12 S盒8: 13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7 1,
15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2 7, 11, 4, 1, 9, 12,
14, 2, 0, 6, 10, 13, 15, 3, 5, 8 2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9,
0, 3, 5, 6, 11