Just playing around with ciphers again. No really use for this nowadays since it’s easilly broken, but I figured I’ll post it here anyway.


Here you can generate a cipher text based on rotation/shift in the alphabet.


Remember that the chars that will be shifted are ABCDEFGHIJKLMNOPQRSTUVWXYZ.

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Here’s the javascript source:

var ROT = {
    chars: 'ABCDEFGHIJKLMNOPQRSTUVWXYZ',
    generate: function(plaintext, shift)
    {
        var ciphertext = this.rotate(plaintext, parseInt(shift));
        return ciphertext;
    },
    solve: function(ciphertext, shift)
    {
        var plaintext = this.rotate(ciphertext, -1*parseInt(shift));
        return plaintext;
    },
    rotate: function(str, shift, pos)
    {
        var pos = pos || 0;

        if(!str.length)
            return '';

        var old_char = str.charAt(pos);
        var old_pos = this.chars.indexOf(old_char.toUpperCase());

        if(old_pos < 0)//Some other character
            return old_char.toUpperCase() + this.rotate(str, shift, pos+1);

        var new_pos = (old_pos + shift) % this.chars.length;
        new_pos = new_pos < 0 ? this.chars.length + new_pos : new_pos;

        var new_char = this.chars.charAt(new_pos);

        if(str.length-1 > pos)
            return new_char + this.rotate(str, shift, pos+1);

        return new_char;
    }
}