base16 flag 666C6167 base32[A-Z2-7] flag MZWGCZY= base36 flag 727432 base58 flag 3cr9Ae base64 flag Zmxh base85 flag Ao(mg base91 flag @iH<Z base92 flag F#S<I base100 flag 👝👣👘👞 base1024 flag base2048 flag ڥڊװ base65535 flag ꍦ鱡
defalpha(cipher): # 预处理,去掉空格以及回车 c = '' for i inrange(len(cipher)): if (cipher[i].isalpha()): c += cipher[i] return c
defcount_IC(cipher): # 给定字符串计算其重合指数 count = [0for i inrange(26)] L = len(cipher) IC = 0.0 for i inrange(len(cipher)): if (cipher[i].isupper()): count[ord(cipher[i]) - ord('A')] += 1 elif (cipher[i].islower()): count[ord(cipher[i]) - ord('a')] += 1 for i inrange(26): IC += (count[i] * (count[i] - 1)) / (L * (L - 1)) return IC
defcount_key_len(cipher, key_len): # 对字符串按输入个数进行分组，计算每一组的IC值返回平均值 N = [''for i inrange(key_len)] IC = [0for i inrange(key_len)] for i inrange(len(cipher)): m = i % key_len N[m] += cipher[i] for i inrange(key_len): IC[i] = count_IC(N[i]) # print(IC) print("长度为%d时,平均重合指数为%.5f" % (key_len, np.mean(IC))) return np.mean(IC)
deflength(cipher): # 遍历确定最有可能的密钥长度返回密钥长度 key_len = 0 mins = 100 aver = 0.0 for i inrange(1, 10): k = count_key_len(cipher, i) if (abs(k - 0.065) < mins): mins = abs(k - 0.065) key_len = i aver = k print("密钥长度为%d,此时重合指数每组的平均值为%.5f" % (key_len, aver)) return key_len
defcount_MIC(c1, c2, n): # n=k1-k2为偏移量,计算c1,c2互重合指数MIC count_1 = [0for i inrange(26)] count_2 = [0for i inrange(26)] L_1 = len(c1) L_2 = len(c2) MIC = 0 for i inrange(L_1): if (c1[i].isupper()): count_1[ord(c1[i]) - ord('A')] += 1 elif (c1[i].islower()): count_1[ord(c1[i]) - ord('a')] += 1 for i inrange(L_2): if (c2[i].isupper()): count_2[(ord(c2[i]) - ord('A') + n + 26) % 26] += 1 elif (c2[i].islower()): count_2[(ord(c2[i]) - ord('a') + n + 26) % 26] += 1 for i inrange(26): MIC += count_1[i] * count_2[i] / (L_1 * L_2) return MIC
defcount_n(c1, c2): # 确定两个子串最优的相对偏移量n=k1-k2 n = 0 mins = 100 k = [0.0for i inrange(26)] for i inrange(26): k[i] = count_MIC(c1, c2, i) # print(i,k[i]) if (abs(k[i] - 0.065) < mins): mins = abs(k[i] - 0.065) n = i return n
defgroup_k(cipher, key_len): # 完成分组操作并计算每一组与第一组的最优相对偏移量并返回 N = [''for i inrange(key_len)] MIC = [0for i inrange(key_len)] s = [0for i inrange(key_len)] for i inrange(len(cipher)): # 对密文进行分组 m = i % key_len N[m] += cipher[i] for i inrange(1, key_len): # 计算与第一组之间的相对偏移量 s[i] = count_n(N[0], N[i]) # s[i] = k1-k(i+1) MIC[i] = count_MIC(N[0], N[i], s[i]) # MIC[i] = MIC(1,i+1) print("第1组和第%d组之间偏移为%d时，互重合指数为%.5f" % (i + 1, s[i], MIC[i])) return s
defmiyao(key_len, s, k): # k为第一个子串的移位，输出密钥并返回密钥所有字母的下标 mi = [''for i inrange(key_len)] for i inrange(key_len): s[i] = -s[i] + k # k2=k1-n mi[i] = chr((s[i] + 26) % 26 + ord('a')) print("第一个偏移量为%d,密钥为%s时" % (k, mi)) return s
defthe_end(cipher, key_len, s): # 输入密文密钥返回明文结果 plain = '' i = 0 while (i < len(cipher)): for j inrange(key_len): if (cipher[i].isupper()): plain += chr((ord(cipher[i]) - ord('A') - s[j] + 26) % 26 + ord('A')) else: plain += chr((ord(cipher[i]) - ord('a') - s[j] + 26) % 26 + ord('a')) i += 1 if (i == len(cipher)): break # print(plain) return plain
if __name__ == "__main__": fp = open("密文.txt", "r") cipher = '' for i in fp.readlines(): cipher = cipher + i fp.close() cipher = alpha(cipher) key_len = length(cipher) s = group_k(cipher, key_len) m = s.copy() for k inrange(26): s = m.copy() s = miyao(key_len, s, k) plain = the_end(cipher, key_len, s) print(plain[0:20]) # 输出部分明文确定偏移量k1 print("参考输出，请输入第一个子串的偏移量:", end='') k = int(input()) m = miyao(key_len, m, k) plain = the_end(cipher, key_len, m)
'''对英文文本进行分词''' word = wordninja.split(plain) plain = '' for i inrange(len(word)): plain += word[i] plain += ' ' print("明文为\n" + plain)
