Subject: Resolving the newmodes algorithm list.

From: Bill Sommerfeld <[email-masked]>
Date: Tue, 29 Jul 2003 17:32:54 -0400

The current list in http://www.ietf.org/internet-drafts/draft-ietf-secsh-newmodes-00.txt

is:

     aes128-ctr       RECOMMENDED       AES (Rijndael) in SDCTR mode,
                                        with 128-bit key
     aes192-ctr       RECOMMENDED       AES with 192-bit key
     aes256-ctr       RECOMMENDED       AES with 256-bit key
     3des-ctr         RECOMMENDED       Three-key 3DES in SDCTR mode
     blowfish-ctr     RECOMMENDED       Blowfish in SDCTR mode
     twofish128-ctr   RECOMMENDED       Twofish in SDCTR mode,
                                        with 128-bit key
     twofish192-ctr   OPTIONAL          Twofish with 192-bit key
     twofish256-ctr   OPTIONAL          Twofish with 256-bit key
     serpent128-ctr   RECOMMENDED       Serpent in SDCTR mode, with
                                        with 128-bit key
     serpent192-ctr   OPTIONAL          Serpent with 192-bit key
     serpent256-ctr   OPTIONAL          Serpent with 256-bit key
     idea-ctr         OPTIONAL          IDEA in SDCTR mode
     cast128-ctr      OPTIONAL          CAST-128 in SDCTR mode

There seems to be no objection to the concept of downgrading all the
AES runner-ups to OPTIONAL, leaving only the three aes sizes and 3des
as RECOMMENDED.

Namely:

     aes128-ctr       RECOMMENDED       AES (Rijndael) in SDCTR mode,
                                        with 128-bit key
     aes192-ctr       RECOMMENDED       AES with 192-bit key
     aes256-ctr       RECOMMENDED       AES with 256-bit key
     3des-ctr         RECOMMENDED       Three-key 3DES in SDCTR mode
     blowfish-ctr     OPTIONAL          Blowfish in SDCTR mode
     twofish128-ctr   OPTIONAL          Twofish in SDCTR mode,
                                        with 128-bit key
     twofish192-ctr   OPTIONAL          Twofish with 192-bit key
     twofish256-ctr   OPTIONAL          Twofish with 256-bit key
     serpent128-ctr   OPTIONAL          Serpent in SDCTR mode, with
                                        with 128-bit key
     serpent192-ctr   OPTIONAL          Serpent with 192-bit key
     serpent256-ctr   OPTIONAL          Serpent with 256-bit key
     idea-ctr         OPTIONAL          IDEA in SDCTR mode
     cast128-ctr      OPTIONAL          CAST-128 in SDCTR mode

Also, what do people think of boosting aes128-ctr to MANDATORY ?
(note: this is a separate document.  as a practical matter,
implementations would not be "forced" to implement aes128-ctr until
they chose to claim they implemented newmodes).

					- Bill

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From: [email-masked] (David Wagner)
Date: Tue, 29 Jul 2003 21:35:03 +0000 (UTC)

>AES runner-ups to OPTIONAL, leaving only the three aes sizes and 3des

As one of the co-designers of one of the algorithms that was downgraded,
I warmly support your proposed downgrading.

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From: Nicolas Williams <[email-masked]>
Date: Tue, 29 Jul 2003 15:35:45 -0700

> they chose to claim they implemented newmodes).

I agree.  If two implementations support newmodes they should be able to
interop, and that means having at least one mode be required to
implement.

Nico
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