Re: [ANN] Lua 5.2.0 (work5) now available

[Sean Conner <sean@...>]

It was thus said that the Great pj@pjb.com.au once stated:
> Joseph Stewart wrote:
> > but what can't you do with 32-bit values that you need to do?
> 
> I wrote:
> > Strong encryption ?
> > In block cyphers, you need lots of XOR ops, and block sizes of
> > 32 bits are inherently vulnerable but 64 bits are very tough...
> 
> Rob Kendrick wrote:
> > It's difficult to see how simply doubling the number of bits
> > you process at once removes an inherent vulnerability.
> 
> See:   http://en.citizendium.org/wiki/Code_book_attack
> 
>   DES and the generation of ciphers that followed it all used a 64-bit
>   block size. To completely break a single key, an attacker would need
>   a code book with 2^64 entries. Even to weaken it significantly takes
>   a code book with 2^32 entries with the same key, 32 gigabytes of data.
>   With any sensible re-keying policy, a code book attack is not a threat.
>   More recent ciphers such as AES use a 128-bit block size,
>   which makes code book attacks utterly impractical.

  Um, there's processing a DES block with two 32-bit quantities, or
processing a DES block with one 64-bit quantity.  As far as I know, DES
isn't even defined for 32-bit blocks. 

  -spc (Or heck, you can process a DES block as 8 8-bit quantities, although
	it might be a bit slow ... )