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comp.lang.ruby

Flaw in ruby-crypt's GOST implementation

Hartog C. de Mik

3/7/2009 4:33:00 PM



2 Answers

Hartog C. de Mik

3/7/2009 4:40:00 PM

0

On Sun, Mar 08, 2009 at 01:33:14AM +0900, Hartog C. de Mik wrote:
>
>

... is it that I PGP sign my messages that no text appears?

Let's try again - I have found a flaw in the pure Ruby
crypto-suite. It concerns the GOST implementation.

If you are using GOST as a cipher I would advice you to switch to an
other cipher until the problem is propperly fixed.

Please read my blog post (http://...) for more information.



Kind Regards,


Hartog C. de Mik
--
-.-. --- ..-. ..-. . . .- -.. -.. .. -.-. -

Nobuyoshi Nakada

3/9/2009 9:46:00 AM

0

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://...) for more information.

> http://www.coffeeaddict.nl/blog/200...

> 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