[Cryptography] Is ASN.1 still the thing?

[Erwann ABALEA]

Le mar. 14 nov. 2017 à 23:51, Nico Williams <nico at cryptonector.com> a
écrit :

> On Mon, Nov 13, 2017 at 04:26:47PM -0500, Jerry Leichter wrote:
> > I haven't seen a direct comparison, but I very much doubt ASN.1 would
>
> Can we be a bit more pedantically correct?  ASN.1 is *syntax* and has an
> associated set of encoding rules.
>
> Those rules include:
>
>  - tag-length-value (TLV) encoding rules that suck: BER, DER, CER
>
>  - PER -- an XDR-like set of rules, but with 1-byte alignment (vs.
>    4-byte alignment for XDR)
>

Pedantically-wise, PER is bit-aligned, and some padding bits can be added
for octet alignment. The Unaligned variant of PER (UPER) is strictly
bit-aligned.

PER also can support the encoding of data with a reduced number of bits
when told so. For example if a field is declared as 2 characters from the
[A,Z] set, an instance of this field will be encoded using 10 bits only.
Similar optimizations are applied to integers.

-- 
Erwann.
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