[Cryptography] Shortening block cipher length...

Jon Callas jon at callas.org
Mon Mar 29 21:17:57 EDT 2021



> On Mar 29, 2021, at 16:19, Peter Gutmann <pgut001 at cs.auckland.ac.nz> wrote:
> 
> Jon Callas <jon at callas.org> writes:
> 
>> For that matter, what's wrong with Counter Mode?
> 
> It turns any strong block cipher into the functional equivalent of RC4.  So
> what you're saying there is "what's wrong with RC4"?

I think it's very different when you're encrypting a 64-bit block, especially a single one, which is what I understand the use case to be. 

Anyway, you're attacking my flourish, and ignoring the main point -- CFB, which really does let you turn a long block cipher into a short one. I presume that you're okay with that.

	Jon



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