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Re: [COSE] Help with RFC8152 encryption example

Carsten Bormann <cabo@tzi.org> Mon, 10 May 2021 10:35 UTC

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From: Carsten Bormann <cabo@tzi.org>
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Date: Mon, 10 May 2021 12:35:16 +0200
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To: Anders Rundgren <anders.rundgren.net@gmail.com>
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Subject: Re: [COSE] Help with RFC8152 encryption example
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Hi Anders,

> On 10. May 2021, at 11:24, Anders Rundgren <anders.rundgren.net@gmail.com> wrote:
> I took this simple sample:
> https://datatracker.ietf.org/doc/html/rfc8152#appendix-C.4.1
> 
> and adjusted it to fit Carsten's http://cbor.me/
> 
> 16(
>      [
>         {
>             1:10
>          } ,
>        {
>           5:h'89f52f65a1c580933b5261a78c'
>        },
>         h'5974e1b99a3a4cc09a659aa2e9e7fff161d38ce71cb45ce460ffb569'
>      ]
> 
> It returns 51 bytes but the RFC says 52 bytes.

The example in the RFC is (comments removed)

16([h'A1010A', {5: h'89F52F65A1C580933B5261A78C'}, h'5974E1B99A3A4CC09A659AA2E9E7FFF161D38CE71CB45CE460FFB569’])

Or, if you enable cbor.me to show embedded CBOR [1],

16([<< {1: 10} >>, {5: h'89F52F65A1C580933B5261A78C'}, h'5974E1B99A3A4CC09A659AA2E9E7FFF161D38CE71CB45CE460FFB569’])

http://cbor.me/?bytes=D0(83(43(A1010A)-A1(05-4D(89F52F65A1C580933B5261A78C))-58.1C(5974E1B99A3A4CC09A659AA2E9E7FFF161D38CE71CB45CE460FFB569)))

Your example however is missing the 43 byte: The map {1:10} needs to be, CBOR encoded, kept in a byte string.

Grüße, Carsten

[1]: https://datatracker.ietf.org/doc/html/rfc8610#appendix-G.3

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