Subject: [Cfrg] I-D Action: draft-arciszewski-xchacha-03.txt

From: [email-masked]
Date: Tue, 18 Dec 2018 10:26:14 -0800

A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Crypto Forum RG of the IRTF.

        Title           : XChaCha: eXtended-nonce ChaCha and AEAD_XChaCha20_Poly1305
        Author          : Scott Arciszewski
	Filename        : draft-arciszewski-xchacha-03.txt
	Pages           : 15
	Date            : 2018-12-18

Abstract:
   The eXtended-nonce ChaCha cipher construction (XChaCha) allows for
   ChaCha-based ciphersuites to accept a 192-bit nonce with similar
   guarantees to the original construction, except with a much lower
   probability of nonce misuse occurring.  This enables XChaCha
   constructions to be stateless, while retaining the same security
   assumptions as ChaCha.

   This document defines XChaCha20, which uses HChaCha20 to convert the
   key and part of the nonce into a subkey, which is in turn used with
   the remainder of the nonce with ChaCha20 to generate a pseudorandom
   keystream (e.g. for message encryption).

   This document also defines AEAD_XChaCha20_Poly1305, a variant of
   [RFC7539] that utilizes the XChaCha20 construction in place of
   ChaCha20.

The IETF datatracker status page for this draft is:
https://datatracker.ietf.org/doc/draft-arciszewski-xchacha/

There are also htmlized versions available at:
https://tools.ietf.org/html/draft-arciszewski-xchacha-03
https://datatracker.ietf.org/doc/html/draft-arciszewski-xchacha-03

A diff from the previous version is available at:
https://www.ietf.org/rfcdiff?url2=draft-arciszewski-xchacha-03

Please note that it may take a couple of minutes from the time of submission
until the htmlized version and diff are available at tools.ietf.org.

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/

---

From: Scott Arciszewski <[email-masked]>
Date: Tue, 18 Dec 2018 13:33:00 -0500

The major changes between draft02 and draft03 are:

- Neil Madden's suggested wording changes that contrast extended-nonce
cascades with NMR constructions were applied.

- The test vector for XChaCha20 was changed to use the block_counter = 1
rather than block_counter = 0.
  See [1] and [2] for the discussion that led to this change. The wording
has also been updated to make
  this clearer for implementors.

I believe the next steps are:

1. Rename the draft.
2. Amend the working group section of the metadata. (Do I just put "CFRG"?)
3. Any other changes deemed necessary or helpful before a draft04 or
draft05.

If this sounds correct, great. If not, please let me know. :)

[1]: https://github.com/bikeshedders/xchacha-rfc/issues/11
[2]: https://github.com/bikeshedders/xchacha-rfc/issues/12

Scott Arciszewski
Chief Development Officer
Paragon Initiative Enterprises <https://paragonie.com>

On Tue, Dec 18, 2018 at 1:26 PM <[email-masked]> wrote:

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