[EMAIL PROTECTED] (James A. Donald) on Thursday, September 14, 2006 wrote: >Obviously we do need a standard for describing structured data, and we >need a standard that leads to that structured data being expressed >concisely and compactly, but seems to me that ASN.1 is causing a lot of >grief. > >What is wrong with it, what alternatives are there to it, or how can it >be fixed?
In SPKI we used S-Expressions. They have the advantage of being simple, perhaps even too simple. In describing interfaces in the KeyKOS design document <http://www.cis.upenn.edu/~KeyKOS/agorics/KeyKos/Gnosis/keywelcome.html> we used a notation similar to S-Expressions which was: (length, data) These could be combined into a structure: e.g. (4, len), (len, data) for data proceeded by a four byte length field. If you standardize that the data is always right justified in a field of length "len", and that binary data is encoded with a standard encoding (hexadecimal, 6-bit/character, decimal etc.), most of the problems I have seen described in this thread should "just go away". Some might object that having a specific number of bits for the length field limits future expansion of this approach. Indeed, ASN.1 avoids this issue by allowing the encoding of "infinite" length integers, and XML does the same. The cost of that flexibility is much more difficult encoding and decoding. If a length field length of 4 to 8 bytes (32 to 64 bits) is chosen, as a practical matter, any length data that is transmittable in an exchange can be represented. (A terabit/second is 10**12 bits/second. 32 bits can represent a million seconds at that data rate. 64 bits can represent much longer data items.) Cheers - Bill ----------------------------------------------------------------------- Bill Frantz | gets() remains as a monument | Periwinkle (408)356-8506 | to C's continuing support of | 16345 Englewood Ave www.pwpconsult.com | buffer overruns. | Los Gatos, CA 95032 --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]
