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# xorz
It is basically a transformed vigenere.
There is no original idea ,and all codes are my own.
## problem
```python
from itertools import *
from data import flag,plain
key=flag.strip("de1ctf{").strip("}")
assert(len(key)<38)
salt="WeAreDe1taTeam"
ki=cycle(key)
si=cycle(salt)
cipher = ''.join([hex(ord(p) ^ ord(next(ki)) ^ ord(next(si)))[2:].zfill(2) for p in plain])
print cipher
# output:
# 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
```
## solve.py
```python
#coding:utf8
from itertools import cycle
c="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"
def getCipher(c):
codeintlist = []
codeintlist.extend(
(map(lambda i: int(c[i:i + 2], 16), range(0, len(c), 2))))
salt="WeAreDe1taTeam"
si=cycle(salt)
newcodeintlist = [ci ^ ord(next(si)) for ci in codeintlist]
return newcodeintlist
def getKeyPool(cipher, stepSet, plainSet, keySet):
''' all inputs are like:
[0x11,0x22,0x33]
output is like:
{
1:[[0x11]],
3:[
[0x11,0x33,0x46],
[0x22,0x58],
[0x33]
]
}
'''
keyPool = dict()
for step in stepSet:
maybe = [None] * step
for pos in xrange(step):
maybe[pos] = []
for k in keySet:
flag = 1
for c in cipher[pos::step]:
if c ^ k not in plainSet:
flag = 0
if flag:
maybe[pos].append(k)
for posPool in maybe:
if len(posPool) == 0:
maybe = []
break
if len(maybe) != 0:
keyPool[step] = maybe
return keyPool
def calCorrelation(cpool):
'''input like:{'e':2,'p':3}
output: possibility ,which is between 0 and 1.
(correlation between the decrypted column letter frequencies and
the relative letter frequencies for normal English text)
'''
frequencies = {"e": 0.12702, "t": 0.09056, "a": 0.08167, "o": 0.07507, "i": 0.06966,
"n": 0.06749, "s": 0.06327, "h": 0.06094, "r": 0.05987, "d": 0.04253,
"l": 0.04025, "c": 0.02782, "u": 0.02758, "m": 0.02406, "w": 0.02360,
"f": 0.02228, "g": 0.02015, "y": 0.01974, "p": 0.01929, "b": 0.01492,
"v": 0.00978, "k": 0.00772, "j": 0.00153, "x": 0.00150, "q": 0.00095,
"z": 0.00074}
relative = 0.0
total = 0
fpool = 'etaoinshrdlcumwfgypbvkjxqz'
total = sum(cpool.values()) # include all printable chars
for i in cpool.keys():
if i in fpool:
relative += frequencies[i] * cpool[i] / total
return relative
def analyseFrequency(cfreq):
key = []
for posFreq in cfreq:
mostRelative = 0
for keyChr in posFreq.keys():
r = calCorrelation(posFreq[keyChr])
if r > mostRelative:
mostRelative = r
keychar = keyChr
key.append(keychar)
return key
def getFrequency(cipher, keyPoolList):
''' input like: [1,2,3]
keyPoolList like:[[0x11,0x12],[0x22]]
output like:
[{
0x11:{'a':2,'b':3},
0x12:{'e':6}
},
{
0x22:{'g':1}
}]
'''
freqList = []
keyLen = len(keyPoolList)
for i in xrange(keyLen):
posFreq = dict()
for k in keyPoolList[i]:
posFreq[k] = dict()
for c in cipher[i::keyLen]:
p = chr(k ^ c)
posFreq[k][p] = posFreq[k][p] + 1 if p in posFreq[k] else 1
freqList.append(posFreq)
return freqList
def vigenereDecrypt(cipher, key):
plain = ''
cur = 0
ll = len(key)
for c in cipher:
plain += chr(c ^ key[cur])
cur = (cur + 1) % ll
return plain
def main():
ps = []
ks = []
ss = []
ps.extend(xrange(32, 127))
ks.extend(xrange(0xff + 1))
ss.extend(xrange(38))
cipher = getCipher(c)
keyPool = getKeyPool(cipher=cipher, stepSet=ss, plainSet=ps, keySet=ks)
for i in keyPool:
freq = getFrequency(cipher, keyPool[i])
key = analyseFrequency(freq)
plain = vigenereDecrypt(cipher, key)
print plain,"\n"
print ''.join(map(chr,key))
if __name__ == '__main__':
main()
# output: Wvlc0m3tOjo1nu55un1ojOt3q0cl3W rectify output to get flag
# data.py content：
# flag="de1ctf{W3lc0m3tOjo1nu55un1ojOt3m0cl3W}"
# plain="In faith I do not love thee with mine eyes,For they in thee a thousand errors note;But `tis my heart that loves what they despise,Who in despite of view is pleased to dote.Nor are mine ears with thy tongue`s tune delighted;Nor tender feeling to base touches prone,Nor taste, nor smell, desire to be invitedTo any sensual feast with thee alone.But my five wits, nor my five senses canDissuade one foolish heart from serving thee,Who leaves unswayed the likeness of a man,Thy proud heart`s slave and vassal wretch to be.Only my plague thus far I count my gain,That she that makes me sin awards me pain."
```
