Subject: [Cbor] [Technical Errata Reported] RFC8610 (6543)

From: RFC Errata System <[email-masked]>
Date: Tue, 13 Apr 2021 17:13:22 -0700 (PDT)

The following errata report has been submitted for RFC8610,
"Concise Data Definition Language (CDDL): A Notational Convention to Express Concise Binary Object Representation (CBOR) and JSON Data Structures".

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You may review the report below and at:
https://www.rfc-editor.org/errata/eid6543

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Type: Technical
Reported by: Sean Bartell <[email-masked]>

Section: B

Original Text
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     bytes = [bsqual] %x27 *BCHAR %x27
     BCHAR = %x20-26 / %x28-5B / %x5D-10FFFD / SESC / CRLF

Corrected Text
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     bytes = %x27 *BCHAR %x27
           / bsqual %x27 *QCHAR %x27
     BCHAR = %x20-26 / %x28-5B / %x5D-10FFFD / SESC / CRLF
     QCHAR = DIGIT / ALPHA / "+" / "/" / "-" / "_" / "=" / WS

Notes
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Section 3.1 states that comments are allowed in prefixed byte strings. This correction explicitly uses WS (which includes comments) in the rule for prefixed byte strings. Although the original ABNF would allow *most* comments, it would prohibit comments including a single quote, or comments with a backslash at the end of the line.

My correction allows prefixed byte strings to use every hex and base64 character. Alternatively, the ABNF could be narrowed down using separate rules for hex and base64, or it could be broadened to allow other characters. The ultimate effect would be the same regardless.

Note that both the original and corrected ABNF allow CRLF in unprefixed bytestrings.

(Note: Unlike my previous two errata, which affected unprefixed byte strings, this one affects prefixed byte strings.)

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RFC8610 (draft-ietf-cbor-cddl-08)
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Title               : Concise Data Definition Language (CDDL): A Notational Convention to Express Concise Binary Object Representation (CBOR) and JSON Data Structures
Publication Date    : June 2019
Author(s)           : H. Birkholz, C. Vigano, C. Bormann
Category            : PROPOSED STANDARD
Source              : Concise Binary Object Representation Maintenance and Extensions
Area                : Applications and Real-Time
Stream              : IETF
Verifying Party     : IESG