From: Nobuyoshi Nakada <nobu@...>
Date: 2009-03-09T18:45:43+09:00
Subject: Re: Flaw in ruby-crypt's GOST implementation

Hi,

At Sun, 8 Mar 2009 01:39:32 +0900,
Hartog C. de Mik wrote in [ruby-talk:330604]:
> Please read my blog post (http://is.gd/m4K1) for more information.

> http://www.coffeeaddict.nl/blog/20090306/171/

> I patched my version of gost.rb to use the key preparation I
> found in the C# version of bouncycastle.org. Where the
> original code has become:
> 
> # derive the 32-byte key from the user-supplied key
> if (userKey.length < 32)
>   userKey.length.upto(31) { userKey = userKey << "0" }
> end 
> 
> # make the 8 sub keys
> @key = []
> for i in (0..7)
>   @key[i] = bytesToInt(userKey,i*4);
> end

It can be done more concisely.

  @key = userKey[0...32].ljust(32, "\0").unpack("V*")

-- 
Nobu Nakada