Re: [ASN.1] Asn.1 and ROSE problems

[Rajul Gupta]

Title: Re: [ASN.1] Asn.1 and ROSE problems

Hi Vasa,   I can give you some information about DER and CER. Other members of group can give you more detailed information. You have already written DER and CER are derived from BER, but these are more restrictive. You can't have two different encodings for the same value.   For example, encoding of "value BOOLEAN ::= TRUE" can be anything between 0x01 to 0xFF in BER, but it has to be 0xFF in CER/DER. There are so many other examples like this.   These encoding rules are helpful for the applications that relay information associated with digital signature. Main difference between CER and DER, former uses indefinite-length format, and later uses definite-length format. Messages encoded by DER/CER can be decoded by BER decoder, but reverse is not true. I have seen not many people use CER, they use DER instead. However, I may be wrong. You can get more info about this from the books available at www.oss.com , or may be other places from the net.   Rajul Gupta OSS Nokalva [EMAIL PROTECTED] 1-732-302-9669 (x-137) http://www.oss.com ----- Original Message ----- From: Prasad Vasa To: '[EMAIL PROTECTED]' Sent: Tuesday, August 27, 2002 6:17 AM Subject: RE: [ASN.1] Asn.1 and ROSE problems hello, Can any body explain what is canonical-encoding(0)  and distinguished-encoding(1) What is the difference between them? Both the above encodings are derived forms of BER ( http://asn1.elibel.tm.fr/en/oid/root/joint-iso-itu-t/asn1/ber-derived/ )   I await your reply   Warm regards, Vasa -----Original Message----- From: DUBUISSON Olivier [mailto:[EMAIL PROTECTED]] Sent: Sunday, August 11, 2002 1:25 AM To: [EMAIL PROTECTED]; [EMAIL PROTECTED] Cc: zze-BARBEAU Julien FTRD/DTL/LAN Subject: Re: [ASN.1] Asn.1 and ROSE problems Bernard Kufluk wrote: > > Hi > > I am at the early stages in a project involving ASN.1 and ROSE. > I have obtained the X.219, 229 etc specs from the ITU and cut and pasted You seem to be using old versions of ROSE. The ASN.1 modules of the latest version (the X.880 series) is available from: http://www.itu.int/itu-t/asn1/database/itu-t/x/ > from the PDF to create the documents - but I'm a bit surprised that the > specs seem to have errors in them (spelling mistakes etc). > Does anyone have experience of this and is this normal ? Of course clean ASN.1 modules are expected, but this is unfortunately the case that standardization organizations sometimes publish standards which have not been thoroughly checked (as you can imagine this is a matter of time and manpower -- so feel free to join, say, the ITU-T and help improve the quality of what is produced, your help is much welcome).   > (Am I going > about this completely the wrong way ?) France Telecom is giving a lot of manpower to the ITU-T ASN.1 Project (see http://www.itu.int/itu-t/asn1) to extract the ASN.1 modules from all ITU-T Recommendations, check them with a compiler and pretty-print them into both a text and HTML (with hyperlinks) format. We provide a lot of other useful features such as a dependence tree, zipped packages gathering all ASN.1 modules needed to compile a Recommendation...). The result is freely available from the ITU-T website at: http://www.itu.int/itu-t/asn1/database/ (Of course not all Recommendations are available yet but we are working hard to improve this.) -- Olivier DUBUISSON (ITU-T ASN.1 Project leader) france telecom R&D DTL/TAL - 22307 Lannion Cedex - France t: +33 2 96 05 38 50 - f: +33 2 96 05 39 45 - http://asn1.elibel.tm.fr/