pyBestCaesarDecrypt by letter frequency

# Caesar Cypher Decoding
# Decode some text by finding out what Caesar offset produces the best result based on the
# characters in the resultant text, scored by their frequency in typical English text


def caesar_decrypt(intext):
    # Arrange alphabet in reverse order of frequency, so that the index position corresponds to a score for that letter
    LetterDistr = "xqjzvkywgfbpmculdrhsnioate"
    # letters occurring near the front of LetterDistr score low. Letters towards the end score high.

    # Decode the input text using all possible Caesar offsets, 0 to 25, in turn
    # For each of the 26 results, compute the sum of the scores for the letters
    # For example, every "e" in the output scores 25*25, whereas "x" scores 0

    bestscore = 0
    for off in range(0, 26):            # Try each offset (0 to 25) in turn
        otext = ""
        score = 0
        for ch in intext:
            x = ord(ch) - ord('a')      # compute the distance of ch from 'a' in alphabet
            x += off                    # add the current Caesar offset
            x %= 26                     # wrap around 26 letters
            char = chr(x + ord('a'))
            otext += char               # build the decoded output text
            if char in LetterDistr:
                weight = LetterDistr.index(char)        # get letter weight based on frequency in English
                score += weight * weight    # exaggerate the weight variance and accumulate a message score
        if score > bestscore:
            bestscore = score           # remember the best score so far
            bestkey = off               # remember the offset that gave the best score so far
            bestout = otext             # remember the best decyphered text so far
        # print(off, score, otext)          # optional progress print
    print("Best Offset: ", bestkey)
    print("Decrypted text: ", bestout)


encrypted_text = "kyvfecpkzdvjyvljvurjtivnuizmvinrjpvjkviurp"
caesar_decrypt(encrypted_text)

# Output
# Best Offset:  9
# Decrypted text:  theonlytimesheusedascrewdriverwasyesterday