凱撒密碼破譯
from my csdn blog
信息安全原理 hw1
Caesar: AWPLDPPYNCJAEJZFCYLXPHTESESPDLXPVPJLYODPYOEZESPEL
破譯該密碼礼殊，并做破譯出的明文指定的事情
凱撒密碼是位移密碼,寫個程序遍歷出所有結(jié)果
#casesarTest.py
cipher = 'AWPLDPPYNCJAEJZFCYLXPHTESESPDLXPVPJLYODPYOEZESPEL'
def decoding(cipher):
'''try to decoding cipher and show all result'''
def transform(key):
for alpha in key:
beta = key[alpha]
beta = chr(ord(beta) + 1)
if ord(beta) > ord('Z'):
beta = 'A'
key[alpha] = beta
return key
key = {}
cipherTest = ''
for alpha in range(ord('A'), ord('A')+26):
key[chr(alpha)] = chr(alpha)
for i in range(26):
cipherTest = ''
for j in range(len(cipher)):
cipherTest += key[cipher[j]]
key = transform(key)
print('{0:2} : {1}'.format(i, cipherTest))
decoding(cipher)
amrzs@ubuntu:security$ python3 caesarTest.py > result.txt
0 : AWPLDPPYNCJAEJZFCYLXPHTESESPDLXPVPJLYODPYOEZESPEL
1 : BXQMEQQZODKBFKAGDZMYQIUFTFTQEMYQWQKMZPEQZPFAFTQFM
2 : CYRNFRRAPELCGLBHEANZRJVGUGURFNZRXRLNAQFRAQGBGURGN
3 : DZSOGSSBQFMDHMCIFBOASKWHVHVSGOASYSMOBRGSBRHCHVSHO
4 : EATPHTTCRGNEINDJGCPBTLXIWIWTHPBTZTNPCSHTCSIDIWTIP
5 : FBUQIUUDSHOFJOEKHDQCUMYJXJXUIQCUAUOQDTIUDTJEJXUJQ
6 : GCVRJVVETIPGKPFLIERDVNZKYKYVJRDVBVPREUJVEUKFKYVKR
7 : HDWSKWWFUJQHLQGMJFSEWOALZLZWKSEWCWQSFVKWFVLGLZWLS
8 : IEXTLXXGVKRIMRHNKGTFXPBMAMAXLTFXDXRTGWLXGWMHMAXMT
9 : JFYUMYYHWLSJNSIOLHUGYQCNBNBYMUGYEYSUHXMYHXNINBYNU
10 : KGZVNZZIXMTKOTJPMIVHZRDOCOCZNVHZFZTVIYNZIYOJOCZOV
11 : LHAWOAAJYNULPUKQNJWIASEPDPDAOWIAGAUWJZOAJZPKPDAPW
12 : MIBXPBBKZOVMQVLROKXJBTFQEQEBPXJBHBVXKAPBKAQLQEBQX
13 : NJCYQCCLAPWNRWMSPLYKCUGRFRFCQYKCICWYLBQCLBRMRFCRY
14 : OKDZRDDMBQXOSXNTQMZLDVHSGSGDRZLDJDXZMCRDMCSNSGDSZ
15 : PLEASEENCRYPTYOURNAMEWITHTHESAMEKEYANDSENDTOTHETA
16 : QMFBTFFODSZQUZPVSOBNFXJUIUIFTBNFLFZBOETFOEUPUIFUB
17 : RNGCUGGPETARVAQWTPCOGYKVJVJGUCOGMGACPFUGPFVQVJGVC
18 : SOHDVHHQFUBSWBRXUQDPHZLWKWKHVDPHNHBDQGVHQGWRWKHWD
19 : TPIEWIIRGVCTXCSYVREQIAMXLXLIWEQIOICERHWIRHXSXLIXE
20 : UQJFXJJSHWDUYDTZWSFRJBNYMYMJXFRJPJDFSIXJSIYTYMJYF
21 : VRKGYKKTIXEVZEUAXTGSKCOZNZNKYGSKQKEGTJYKTJZUZNKZG
22 : WSLHZLLUJYFWAFVBYUHTLDPAOAOLZHTLRLFHUKZLUKAVAOLAH
23 : XTMIAMMVKZGXBGWCZVIUMEQBPBPMAIUMSMGIVLAMVLBWBPMBI
24 : YUNJBNNWLAHYCHXDAWJVNFRCQCQNBJVNTNHJWMBNWMCXCQNCJ
25 : ZVOKCOOXMBIZDIYEBXKWOGSDRDROCKWOUOIKXNCOXNDYDRODK
第15行是什么秉扑？拉出來看看
15 : PLEASE ENCRYPT YOUR NAME WITH THE SAME KEY AND SEND TO THE TA
那么先把密鑰弄出來季稳，已經(jīng)可以看出是位移15位
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
P Q R S T U V W X Y Z A B C D E F G H I J K L M N O
KEY_SHIFT = 15
def getKey(shift):
'''get the key with the shift'''
key = {}
for alpha in range(ord('A'), ord('A')+26):
beta = alpha + shift - 26 if alpha + shift > ord('Z') else alpha + shift
key[chr(alpha)] = chr(beta)
return key
def printKey(key):
'''print the key'''
for alpha in range(ord('A'), ord('A')+26):
print('{0} '.format(chr(alpha)), end=' ')
print()
for alpha in range(ord('A'), ord('A')+26):
print('{0} '.format(key[chr(alpha)]), end=' ')
print()
key = getKey(KEY_SHIFT)
printKey(key)
接下來就是加密自己的名字
def encrypt(key, plaintext):
'''encrypt the string and return the cipher'''
ciphertext = ''
for i in range(len(plaintext)):
ciphertext += key[plaintext[i]]
return ciphertext
MY_NAME = 'AMRZS' #english name
cipher = encrypt(key, MY_NAME)
print(cipher)
amrzs@ubuntu:security$ python3 caesar.py
PBGOH
