Re: A Paranoid Encryption Mode

From: Kenneth Almquist (ka_at_sorry.no.email)
Date: 01/06/04 

Date: 5 Jan 2004 19:20:34 -0500

John Savard wrote:
> On 4 Jan 2004 20:17:06 -0500, ka@sorry.no.email (Kenneth Almquist)
> wrote, in part:

>> The second possibility--making the session key depend in part on
>> the message body--is equivalent to changing making the session
>> key depend only on the header, and using a different encryption
>> algorithm.
>
> You are quite correct. After all, what I am doing is taking the
> header, and using it as input to an encryption operation performed on
> the message as a whole.
>
> But different encryption algorithms aren't equivalent in security.

Yes, but saying that two algorithms aren't equivalent in security
doesn't tell us *which* of the two algorithms is more secure. In
the article which began this thread, you posted a fairly complex
design. However, you either failed to explain why one might choose
your proposal over a simple design, or else you did explain but I
failed to understand the explanation.
                                Kenneth Almquist

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