From: Josh Cheek <josh.cheek@...>
Date: 2010-07-02T00:44:42+09:00
Subject: Re: New AES gem available -- fast-aes

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2010/7/1 P=E5l Bergstr=F6m <pal@palbergstrom.com>

> I should add that I don't fully understand this thing with encryption
> and the terminology. Could you explain a bit the key length and 128 bit?
> Is it always the length as in your example?
>
>
Empirically yes:

require 'rubygems'
require 'fast-aes'
require 'pp'

key , results =3D String.new , Array.new

for char in [*'a'..'z'] + [*'A'..'H']
  results << begin
    FastAES.new key and "Valid: #{key}"
  rescue =3D> error
    error
  end
  key << char
end

pp results




Definitively (fast_aes.c), still yes:

key_bits =3D strlen(key_data)*8;
switch(key_bits)
{
    case 128:
    case 192:
    case 256:
        fast_aes->key_bits =3D key_bits;
        memcpy(fast_aes->key, key_data, key_bits/8);
        /*printf("AES key=3D%s, bits=3D%d\n", fast_aes->key,
fast_aes->key_bits);*/
        break;
    default:
        sprintf(error_mesg, "AES key must be 128, 192, or 256 bits in lengt=
h
(got %d): %s", key_bits, key_data);
        rb_raise(rb_eArgError, error_mesg);
        return Qnil;
}

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