Re: [TLS] [Technical Errata Reported] RFC5246 (4382)

[Dave Garrett <[e-mail]>]

Based on the definition, the current text is correct. I think the definition is confusing and not particularly helpful, but it's correct.

opaque Datum[3];  // 3 bytes
Datum Data[9];      // 9 bytes
Datum Data<3>;   // 9 bytes

The second notation is only used in RFC5246 in the specification of the SSL2 CLIENT-HELLO for "cipher_specs". Relevant lines quoted:

>      uint8 V2CipherSpec[3];
[...]
>          V2CipherSpec cipher_specs[V2ClientHello.cipher_spec_length];
[...]
>
>   cipher_spec_length
>      This field is the total length of the field cipher_specs.  It
>      cannot be zero and MUST be a multiple of the V2CipherSpec length
>      (3).

The length definition does say it's the total length of the array, not number of elements, so it appears to be using the notation correctly.


Dave


On Friday, May 29, 2015 08:38:51 am Eric Rescorla wrote:
> I do not believe that this report is correct:
> 
> "A vector (single-dimensioned array) is a stream of homogeneous data
> elements.
> The size of the vector may be specified at documentation time or left
> unspecified until runtime. In either case, the length declares the number of
> bytes, not the number of elements, in the vector."
> 
> 
> On Fri, May 29, 2015 at 4:39 AM, RFC Errata System <
> [e-mail]> wrote:
> 
> > The following errata report has been submitted for RFC5246,
> > "The Transport Layer Security (TLS) Protocol Version 1.2".
> >
> > --------------------------------------
> > You may review the report below and at:
> > http://www.rfc-editor.org/errata_search.php?rfc=5246&eid=4382
> >
> > --------------------------------------
> > Type: Technical
> > Reported by: Laura Corcoran <[e-mail]>
> >
> > Section: 4.3
> >
> > Original Text
> > -------------
> > In the following example, Datum is defined to be three consecutive
> >    bytes that the protocol does not interpret, while Data is three
> >    consecutive Datum, consuming a total of nine bytes.
> >
> >       opaque Datum[3];      /* three uninterpreted bytes */
> >       Datum Data[9];        /* 3 consecutive 3 byte vectors */
> >
> >
> > Corrected Text
> > --------------
> > In the following example, Datum is defined to be three consecutive
> >    bytes that the protocol does not interpret, while Data is three
> >    consecutive Datum, consuming a total of nine bytes.
> >
> >       opaque Datum[3];      /* three uninterpreted bytes */
> >       Datum Data[3];        /* 3 consecutive 3 byte vectors */
> >
> >
> > Notes
> > -----
> > The 9 in "Datum Data[9]" should be a 3 because Datum is a data type that
> > consumes 3 bytes, so as written the Data vector is 27 bytes long. To make
> > it a 9 byte vector the 9 must change to a 3.
> >
> > Instructions:
> > -------------
> > This erratum is currently posted as "Reported". If necessary, please
> > use "Reply All" to discuss whether it should be verified or
> > rejected. When a decision is reached, the verifying party (IESG)
> > can log in to change the status and edit the report, if necessary.
> >
> > --------------------------------------
> > RFC5246 (draft-ietf-tls-rfc4346-bis-10)
> > --------------------------------------
> > Title               : The Transport Layer Security (TLS) Protocol Version
> > 1.2
> > Publication Date    : August 2008
> > Author(s)           : T. Dierks, E. Rescorla
> > Category            : PROPOSED STANDARD
> > Source              : Transport Layer Security
> > Area                : Security
> > Stream              : IETF
> > Verifying Party     : IESG