def break_xor(cip):
e_distances = []
for KEYSIZE in range(2, 41):
# 3. For each KEYSIZE, take the first KEYSIZE worth of bytes, and the second
# KEYSIZE worth of bytes, and find the distance between them. Normalize this
# this result by dividing by KEYSIZE.
edit_dist_acc = 0
NUM_AVG = 15
for i in range(0, NUM_AVG):
edit_dist_acc += hamming_d(
cip[KEYSIZE * 2 * i:KEYSIZE * (2 * i + 1)],
cip[KEYSIZE * (2 * i + 1):KEYSIZE * 2 * (i + 1)])
avg_edit_dist = (edit_dist_acc) / float(NUM_AVG)
norm_e_dist = avg_edit_dist / float(KEYSIZE)
e_distances.append((KEYSIZE, norm_e_dist))
# 4. The KEYSIZE with the smallest normalized edit distance is probably the key.
# You could proceed perhaps with the smallest 2-3 KEYSIZE values.
sorted_dist = sorted(e_distances, key=operator.itemgetter(1))
#**DEBUG**
#for i in sorted_dist:
# print i
for KEYSIZE, norm_edit_dist in sorted_dist[:1]:
# 5. Now that you probably know the KEYSIZE: break the ciphertext into blocks
# of KEYSIZE length. Now transpose the blocks: make a block that is the first
# byte of each block, and block that is the second bytes, and so on.
block_cip = ['' for i in range(0, KEYSIZE)]
for index, char in enumerate(cip):
block_cip[index % KEYSIZE] += char
# 7. Solve each block as if it was single-character XOR.
key = ''
for block in block_cip:
key += chr(sbx.decrypt(block.encode('hex'))[0])
print "GUESSED KEY:\n " + key
print "MESSAGE:\n" + rx.rep_xor(cip, key).decode('hex')
def get_xor_bytes(blocks, score_fn):
l = len(blocks)
xor_bytes = [None for i in range(l)]
for i in range(l):
(_, _, xor_bytes[i]) = singlebytexor.decrypt(blocks[i], score_fn)
return bytearray(xor_bytes)
def break_xor(cip):
'''Breaks repeating XOR.
@arg cip The cipher text, in raw bytes (i.e. not encoded in any form).
@return None. Displays the probable key guesses.
'''
e_distances = []
for KEYSIZE in range(2, 41):
# 3. For each KEYSIZE, take the first KEYSIZE worth of bytes, and the second
# KEYSIZE worth of bytes, and find the distance between them. Normalize this
# this result by dividing by KEYSIZE.
edit_dist_acc = 0
NUM_AVG = 15
for i in range(0, NUM_AVG):
edit_dist_acc += hamming_d(cip[KEYSIZE*2*i:KEYSIZE*(2*i + 1)],
cip[KEYSIZE*(2*i + 1):KEYSIZE*2*(i+1)])
avg_edit_dist = (edit_dist_acc) / float(NUM_AVG)
norm_e_dist = avg_edit_dist / float(KEYSIZE)
e_distances.append((KEYSIZE, norm_e_dist))
# 4. The KEYSIZE with the smallest normalized edit distance is probably the key.
# You could proceed perhaps with the smallest 2-3 KEYSIZE values. You could
# also take the average of the edit distances of the first few blocks.
sorted_dist = sorted(e_distances, key=operator.itemgetter(1))
#**DEBUG**
debug = open("/tmp/break_xor_debug-" + strftime("%d-%b-%Y-%H-%M-%S", gmtime()), "w")
for i in sorted_dist:
debug.write(str(i) + "\n")
debug.close()
for KEYSIZE, norm_edit_dist in sorted_dist[:1]:
# 5. Now that you probably know the KEYSIZE: break the ciphertext into blocks
# of KEYSIZE length. Now transpose the blocks: make a block that is the first
# byte of each block, and block that is the second bytes, and so on.
block_cip = ['' for i in range(0, KEYSIZE)]
for index, char in enumerate(cip):
block_cip[index % KEYSIZE] += char
# 7. Solve each block as if it was single-character XOR.
key = ''
for block in block_cip:
key += chr(sbx.decrypt(block.encode('hex'))[0])
print "GUESSED KEY:\n " + key
print "MESSAGE:\n" + rx.rep_xor(cip, key).decode('hex')
import singlebytexor as sbx
for l in open('4.txt').readlines():
# try to decrypt every single 'ciphertext'
s = sbx.decrypt(l.strip())
# if it yields an interesting (i.e. printable) result, display it.
if sbx.printable(s[1]):
print s
from singlebytexor import score, decrypt
with open("4.txt", "r") as f:
for line in f.read().split("\n"):
d = decrypt(line)
if d is not None:
print line, d
# 7b5a4215415d544115415d5015455447414c155c46155f4058455c5b523f Now that the party is jumping