ietf-openpgp
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Re: Resolution on large-block ciphers (e.g., TWOFISH), PGP7

2000-07-17 05:33:23
Yes, I meant Twofish, not Blowfish.

The draft I found at imc.org still says in section 5.5.3:
    - [Optional] If secret data is encrypted, eight-octet Initial
      Vector (IV).

This should now read "an IV of the same length as the cipher block"?

[Is there a more recent draft than that posted at imc.org?  That one
claims to expire June 2000.]

As Werner Koch pointed out last year, this will require an implementation
to know the block size simply in order to parse the rest of the packet.
Given that the only material after the IV is the encrypted part, and thus
won't be readable anyway without support for that cipher, I suppose this
isn't all that serious.  But is there any intention to make the IV size
self-describing for future ciphers, or is this the final plan?

Thanks for the quick responses.