Subject: [Curdle] [Technical Errata Reported] RFC8103 (5353)

From: RFC Errata System <[email-masked]>
Date: Wed, 9 May 2018 19:44:50 -0700 (PDT)

The following errata report has been submitted for RFC8103,
"Using ChaCha20-Poly1305 Authenticated Encryption in the Cryptographic Message Syntax (CMS)".

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You may review the report below and at:
http://www.rfc-editor.org/errata/eid5353

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Type: Technical
Reported by: Kevin Israel <[email-masked]>

Section: 6

Original Text
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   The amount of encrypted data possible in a single invocation of
   AEAD_CHACHA20_POLY1305 is 2^32-1 blocks of 64 octets each, because of
   the size of the block counter field in the ChaCha20 block function.
   This gives a total of 247,877,906,880 octets, which is likely to be
   sufficient to handle the size of any CMS content type.  Note that the
   ciphertext length field in the authentication buffer will accommodate
   2^64 octets, which is much larger than necessary.

Corrected Text
--------------
   The amount of encrypted data possible in a single invocation of
   AEAD_CHACHA20_POLY1305 is 2^32-1 blocks of 64 octets each, because of
   the size of the block counter field in the ChaCha20 block function.
   This gives a total of 274,877,906,880 octets, which is likely to be
   sufficient to handle the size of any CMS content type.  Note that the
   ciphertext length field in the authentication buffer will accommodate
   2^64 octets, which is much larger than necessary.

Notes
-----
The calculated total number of octets that can be encrypted in a single invocation is incorrect. See RFC Errata, Erratum ID 4858, RFC 7539.

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RFC8103 (draft-ietf-curdle-cms-chacha20-poly1305-06)
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Title               : Using ChaCha20-Poly1305 Authenticated Encryption in the Cryptographic Message Syntax (CMS)
Publication Date    : February 2017
Author(s)           : R. Housley
Category            : PROPOSED STANDARD
Source              : CURves, Deprecating and a Little more Encryption
Area                : Security
Stream              : IETF
Verifying Party     : IESG

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From: Russ Housley <[email-masked]>
Date: Thu, 10 May 2018 12:36:17 -0400

It probably make sense for this to be approved.  It has an impact on the P_MAX size.

Russ

> On May 9, 2018, at 10:44 PM, RFC Errata System <[email-masked]> wrote:
> 
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