1import base64
  2import string
  3import collections
  4import csv
  5import random
  6from math import sqrt
  7import itertools
  8import simple_crypto as sc# helper functions
  9
 10stl = 20  # str_tips length
 11do_4 = False
 12
 13# 1. Convert hex to base64 and back.
 14print "\n---- Problem 1: Convert hex to base64 and back ----"
 15p1_hex = "49276d206b696c6c696e6720796f757220627261696e206c696b65206120706f69736f6e6f7573206d757368726f6f6d"
 16p1_b64 = "SSdtIGtpbGxpbmcgeW91ciBicmFpbiBsaWtlIGEgcG9pc29ub3VzIG11c2hyb29t"
 17p1_hex_dec = p1_hex.decode ('hex')
 18p1_b64_enc = base64.b64encode (p1_hex_dec)
 19p1_b64_dec = base64.b64decode (p1_b64_enc)
 20p1_hex_enc = p1_b64_dec.encode ('hex')
 21print "hex (G) :", sc.str_tips (p1_hex, stl) 
 22print "b64 (G) :", sc.str_tips (p1_b64, stl)
 23print "hex_dec :", p1_hex_dec
 24print "b64_enc :", sc.str_tips (p1_b64_enc, stl)
 25print "b64_dec :", p1_b64_dec
 26print "hex_enc :", sc.str_tips (p1_hex_enc, stl)
 27assert p1_b64_enc == p1_b64, 'Hex -> B64 failed'
 28assert p1_b64_dec == p1_hex_dec, 'Decoding mismatch (dec b64 != dec hex)'
 29assert p1_hex_enc == p1_hex, 'b64 -> hex failed'
 30
 31
 32# 2. Fixed XOR
 33print "\n---- Problem 2: Fixed XOR ----"
 34p2_a = "1c0111001f010100061a024b53535009181c"
 35p2_b = "686974207468652062756c6c277320657965"
 36p2_r = "746865206b696420646f6e277420706c6179"
 37p2_a_dec = p2_a.decode ('hex')
 38p2_b_dec = p2_b.decode ('hex')
 39p2_r_dec = p2_r.decode ('hex')
 40p2_o_dec =  sc.xor_string(p2_a_dec, p2_b_dec)
 41print "a_dec   : ", p2_a_dec
 42print "b_dec   : ", p2_b_dec
 43print "a^b (G) : ", p2_r_dec
 44print "a^b     : ", p2_o_dec
 45assert p2_o_dec.encode ('hex') == p2_r, 'a^b failed'
 46
 47
 48# 3. Single-character XOR Cipher
 49print "\n---- Problem 3: Single-character XOR Cipher ----"
 50p3_hex = "1b37373331363f78151b7f2b783431333d78397828372d363c78373e783a393b3736"
 51p3_hex_dec = p3_hex.decode ('hex')
 52f = sc.freq_array_load()
 53key, value = sc.ngram_freq_cos_sim (p3_hex_dec, f)
 54p3_xor_dec = sc.xor_char (p3_hex_dec, key)
 55p3_xor_enc = sc.xor_char (p3_xor_dec, key)
 56p3_hex_enc = p3_xor_enc.encode ('hex')
 57print "p3 dec : ", key
 58print "p3 dec : ", p3_xor_dec
 59assert p3_hex == p3_hex_enc, 'dec/enc failed'
 60
 61# 4. Detect single-character XOR
 62if do_4:
 63    print "\n---- Problem 4: Detect single-character XOR ----"
 64    lines = [line.strip() for line in open('gistfile_p4.txt')]
 65    best = (0,'',"")
 66    f = sc.freq_array_load()
 67    for x in lines:
 68        x_raw = x.decode('hex')
 69        key, value = sc.ngram_freq_cos_sim (x_raw, f)
 70        if value > best[0]:
 71            best = (value, key, x)
 72    print "p4 key : ", best[1]
 73    print "p4 dec : ", sc.xor_str (best[2].decode('hex'),best[1]).strip()
 74
 75
 76# 5. Repeating-key XOR Cipher
 77print "\n---- Problem 5: Repeating-key XOR Cipher ----"
 78p5_str = "Burning 'em, if you ain't quick and nimble\nI go crazy when I hear a cymbal"
 79p5_key = "ICE"
 80p5_enc_hex = "0b3637272a2b2e63622c2e69692a23693a2a3c6324202d623d63343c2a26226324272765272a282b2f20430a652e2c652a3124333a653e2b2027630c692b20283165286326302e27282f"
 81p5_enc = p5_enc_hex.decode('hex')
 82p5_str_enc = sc.xor_str(p5_str,p5_key)
 83p5_str_enc_hex = sc.xor_str(p5_str,p5_key).encode('hex')
 84p5_dec = sc.xor_str(p5_enc, p5_key)
 85print "p5 str     (G) :", sc.str_tips (p5_str, stl)
 86print "p5 enc hex (G) :", sc.str_tips (p5_enc_hex, stl)
 87print "p5 str enc hex :", sc.str_tips (p5_str_enc_hex, stl)
 88print "p5 dec         :", sc.str_tips (p5_dec, stl)
 89assert p5_enc == p5_str_enc, "p5 encryption failed"
 90assert p5_dec == p5_str, "p5 decryption failed"
 91
 92# 5b. Encrypt a bunch of stuff using your repeating-key XOR function
 93keys = 10
 94sa = [] # string array
 95sa.append ("Please! This is supposed to be a happy occasion.")
 96sa.append ("Let's not bicker and argue over who killed who.")
 97sa.append ("Go and boil your bottoms, you sons of silly persons!")
 98sa.append ("Listen, strange women lyin' in ponds distributin' swords is no basis for a system of government.")
 99sa.append ("Supreme executive power derives from a mandate from the masses, not from some farcical aquatic ceremony.")
100for s in sa:
101    for k in range(keys):
102        key_len = random.randint (3,30)
103        key = ''.join (random.choice (string.ascii_letters) for r in range (key_len))
104        assert sc.test_xor (s,key)
105print "Repeating-key XOR tested successfully on:", "\n\t", \
106         len(sa), "strings", "\n\t", \
107         len(sa)*keys, "unique keys"
108
109
110# 6. Break repeating-key XOR
111print "\n---- Problem 6: Break repeating-key XOR ----"
112p6_a = "this is a test"
113p6_b = "wokka wokka!!!"
114p6_hd_ab = sc.hamming_dist (p6_a, p6_b)
115assert p6_hd_ab == 37 # Given
116print "Hamming Distance [", p6_a,",", p6_b,"] =", p6_hd_ab
117p6_str_b64 = ''.join([line.strip() for line in open('gistfile_p6.txt')])
118p6_str = base64.b64decode (p6_str_b64)
119p6_key_len = sc.key_len_finder (p6_str)
120print "Possible p6_key_len :", p6_key_len[0][0],",", p6_key_len[1][0],",", p6_key_len[2][0]
121
122
123
124s = "DFJKSDJFKsjlakfjdsfkd"
125key_len = 5
126
127
128print sc.group_and_trans (s,key_len)
129