Re: Stream cipher against block cipher

From: AE (nospam_at_hidden.com)
Date: 06/30/03 

Date: Mon, 30 Jun 2003 08:12:59 +0200

Mok-Kong Shen wrote:
>
> AE wrote:
>
> [snip]
>
>>It is easy to convert a block cipher to a stream cipher (use an
>>appropriate mode of operation and you've got a cipher as strong as the
>>initial codebook) while it is hard to convert a stream cipher to a block
>>cipher (one can do it your way but dependent of the type of stream
>>cipher one is using the result is either severely flawed or completely
>>broken).
>
>
> While one is on the issue of one type of cipher vs
> another, I just want to say that it might be practically
> sensible to leave open the posssibility of appropriately
> combining stream cipher techniques and block cipher
> techniques in one design, thus eventually reaping the
> benefits from both subfields of crypto methodology.
>
> M. K. Shen

I do agree, and this is done frequently and in different ways - from
stream ciphers as obviously having block ciphers in mind as WAKE to
modern stream ciphers with non-linear feedback like SNOW or, on the
other side of the scope, to Skipjack.

I'm most interested in stream ciphers using block cipher techniques
since I believe stream ciphers are allowing better optimisation due to
their smaller scope while the block ciphers allows better security
analysis and better design decisions from the very beginning due to the
larger amount of public knowledge.

AE

Relevant Pages

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  • Re: Scrypt - Linux crypting tool
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  • Re: and now for something complete different part 2
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  • Re: Needle in a haystack--or is this just stupid? - LONG
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