SECCON 2016 crypt 100 Vigenere cipher

solv.py

import itertools

ALPHA = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ{}'

def encrypt(key, plaintext):
    pairs = zip(plaintext, cycle(key))
    result = ''

    for pair in pairs:
        total = reduce(lambda x, y: ALPHA.index(x) + ALPHA.index(y), pair)
        print pairs,ALPHA[total % 28 ]
        result += ALPHA[total % 28]

    return result.lower()

def decrypt(key, ciphertext):
    pairs = zip(ciphertext, itertools.cycle(key))
    result = ''

    for pair in pairs:
        total = reduce(lambda x, y: ALPHA.index(x) - ALPHA.index(y), pair)
        result += ALPHA[total % 28]

    return result


def show_result(plaintext, key):
    encrypted = encrypt(key, plaintext)
    decrypted = decrypt(key, encrypted)

    print 'Key: %s' % key
    print 'Plaintext: %s' % plaintext
    print 'Encrytped: %s' % encrypted
    print 'Decrytped: %s' % decrypted


import hashlib
import sys

seq = tuple(ALPHA)
comb = list(itertools.permutations(seq,4))
for c in comb:
    c1 = ''.join(c)
    key = "VIGENERE" + c1
    s = decrypt( key ,"LMIG}RPEDOEEWKJIQIWKJWMNDTSR}TFVUFWYOCBAJBQ")
    md5 = hashlib.md5( s ).hexdigest()
    print key ,s,md5    
    if md5 == "f528a6ab914c1ecf856a1d93103948fe" :
        print s
        sys.exit()


# VIGENER?????VIGENER?????VIGENER?????VIGENER
# LMIG}RPEDOEEWKJIQIWKJWMNDTSR}TFVUFWYOCBAJBQ
# SECCON{     BCDEDEF     KLMNOPQ     VWXYYZ}
# VIGENER?????VIGENER?????VIGENER?????VIGENER
# SECCON{A    BCDEDEFG    KLMNOPQR    VWXYYZ}
# VIGENERE????VIGENERE????VIGENERE????VIGENER


# ```
# "  | 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 { } 
#  - + - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
#  A | 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 { } 
#  B | 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 { } A 
#  C | C D E F G H I J K L M N O P Q R S T U V W X Y Z { } A B 
#  D | D E F G H I J K L M N O P Q R S T U V W X Y Z { } A B C 
#  E | E F G H I J K L M N O P Q R S T U V W X Y Z { } A B C D 
#  F | F G H I J K L M N O P Q R S T U V W X Y Z { } A B C D E 
#  G | G H I J K L M N O P Q R S T U V W X Y Z { } A B C D E F 
#  H | H I J K L M N O P Q R S T U V W X Y Z { } A B C D E F G 
#  I | I J K L M N O P Q R S T U V W X Y Z { } A B C D E F G H 
#  J | J K L M N O P Q R S T U V W X Y Z { } A B C D E F G H I 
#  K | K L M N O P Q R S T U V W X Y Z { } A B C D E F G H I J 
#  L | L M N O P Q R S T U V W X Y Z { } A B C D E F G H I J K 
#  M | M N O P Q R S T U V W X Y Z { } A B C D E F G H I J K L 
#  N | N O P Q R S T U V W X Y Z { } A B C D E F G H I J K L M 
#  O | O 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 
#  P | 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 
#  Q | 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 P 
#  R | R S T U V W X Y Z { } A B C D E F G H I J K L M N O P Q 
#  S | S T U V W X Y Z { } A B C D E F G H I J K L M N O P Q R 
#  T | T U V W X Y Z { } A B C D E F G H I J K L M N O P Q R S 
#  U | U V W X Y Z { } A B C D E F G H I J K L M N O P Q R S T 
#  V | V W X Y Z { } A B C D E F G H I J K L M N O P Q R S T U 
#  W | W X Y Z { } A B C D E F G H I J K L M N O P Q R S T U V 
#  X | X Y Z { } A B C D E F G H I J K L M N O P Q R S T U V W 
#  Y | Y Z { } A B C D E F G H I J K L M N O P Q R S T U V W X 
#  Z | Z { } 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 
#  { | { } 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 
#  } | } 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 {

# SECCON{?????PGBAZ
# VIGENER?????VIGENER?????VIGENER?????VIGENER
# LMIG}RPEDOEEWKJIQIWKJWMNDTSR}TFVUFWYOCBAJBQ