Re: 1-bit CFB mode

From: Ernest Hammingweight (hammingweight@hotmail.com)
Date: 02/05/03 

From: hammingweight@hotmail.com (Ernest Hammingweight)
Date: 4 Feb 2003 22:22:42 -0800

Paul Rubin <phr-n2003b@NOSPAMnightsong.com> wrote in message news:<7xsmva1liq.fsf_-_@ruckus.brouhaha.com>...
> Are there any known real-world uses at all for 2-bit or 4-bit CFB
> mode?
Dunno about 2-bit or 4-bit CFB mode but a project that I worked on
used 32-bit CFB mode for a slightly bizarre reason. We wanted to use
some smartcards to do a small amount of encryption. Wassennaar (sp?)
export restrictions meant that to buy a smartcard with 3-DES
encryption required a lot of dealing with bureaucracy and wasted time
and expense. However you could buy a card that could generate 3-DES 4
byte MACs (CBC MAC) without problems. We used the MACs to do 32-bit
CFB mode encryption.

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