final caesar

caesar.py

text = u'In cryptography, a Caesar cipher, also known as Caesar\'s cipher, the shift cipher, Caesar\'s code or Caesar shift, is one of the simplest and most widely known encryption techniques. It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet. For example, with a left shift of 3, D would be replaced by A, E would become B, and so on. The method is named after Julius Caesar, who used it in his private correspondence.'

vowels = ['a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U']
attempts = []
guessed = False

# there are 26 possible ceasar's cyphers "variations"
for i in range(0, 26):

    # shift letters `i` times to the right
    dec_text = ''
    for c in text:
        if ord(c) >= ord('a') and ord(c) <= ord('z'):
            dec_text += chr((((ord(c) + i) - ord('a')) % 26) + ord('a'))
        elif ord(c) >= ord('A') and ord(c) <= ord('Z'):
            dec_text += chr((((ord(c) + i) - ord('A')) % 26) + ord('A'))
        else:
            dec_text += c

    # count groups of 3 or more consonants to estimate the likelihood of the text being right
    consecutive_consonants = 0
    consonant_factor = 0
    for c in dec_text:
        if ((c in vowels) == True) or ((ord(c) < ord('a')) and (ord(c) > ord('Z'))) or (ord(c) > ord('z')) or (ord(c) < ord('A')):
            consecutive_consonants = 0
            continue
        consecutive_consonants += 1
        if consecutive_consonants >= 3:
            consonant_factor += 1
            consecutive_consonants = 0

    # structure the data obtained
    result = {
        'dec_text': dec_text,
        'consonant_factor': consonant_factor
    }

    # store attempts in order of most likely to be right to less likely to be right
    index = 0
    for attempt in attempts:
        if attempt['consonant_factor'] > result['consonant_factor']:
            break
        index += 1
    attempts.insert(index, result)


# print the most probable results
for attempt in attempts:
    if attempt['consonant_factor'] == attempts[0]['consonant_factor']:
        print attempt['dec_text']
    else:
        break