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Message
From: allan at ajfengr.com<allan@a...>
Date: Tue Apr 1 21:14:18 CEST 2008
Subject: [oc] TDES's Initial Value(IV)
The IV is not there. I have also evaluated the TDES and found it
is more accurately called "CBC-capable". I mean the area-optimized
option is usable for CBC application, but the CBC logic is not
included. The speed-optimized option is not usable for a CBC
implementation due to the pipelining.
However, you can easily add CBC capability outside of the core
provided. For encryption:
1) Exor the IV with your first block of plaintext before encrypting
2) Exor each subsequent block of plaintext with the block of
cipertext generated in the previous step.
For decryption:
1) After decrypting the first block of ciphertext, exor the resulting
plaintext with the IV.
2) After decrypting each subsequent block of ciphertext, exor the
resulting plaintext with ciphertext from the previous block.
This can't even be attempted with the speed-optimized version,
because subsequent blocks are started before the previous block has
completed. That is why I think it is more accurate to call the
area-optimized version "CBC-capable"
I found Bruce Schneier's "Applied Cryptography" real helpful for
figuring these things out.
Best regards,
Allan
----- Original Message -----
From: gwkim007 at nate.com<gwkim007@n...>
To:
Date: Mon Mar 31 07:23:39 CEST 2008
Subject: [oc] TDES's Initial Value(IV)
> Hello, Everyone.
>
> I am evaluating the TDES (prj name : des).
>
> On the Tripple DES's CBC Mode, Initial Vector(IV) is needed.
> But I couldn't find that in rtl code.
> Plz, describe that.
> Thks for reading!
>
>
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