> > Since no class is specified, both tags default to > > context-specific > > This specification is not a context-specific tag class > but its a APPLICATION tag type which is given > ([APPLICATION 20]) in the specification itself. > > Please correct me if im wrong.
I'm afraid you're wrong. As it's written in the extract Mr. Rios sent, it's only the SEQUENCE which bears an APPLICATION tag, not the elements of that SEQUENCE. The elements use, as Zemer says, context-specific tags ===================================================================== Conrad Sigona Voice Mail : 1-732-302-9669 x400 OSS Nokalva Fax : 1-419-831-5035 [EMAIL PROTECTED] My direct line : 1-315-845-1773 > --- Zemer Margolin <[EMAIL PROTECTED]> wrote: > > Hi, > > For that reason exactly, the tagged typed were > > added. > > In this case the tag [2] is assigned to usec and [3] > > to seq-number. > > Since no class is specified, both tags default to > > context-specific, the ambiguity you've mentioned is > > removed and you can determine which elements are > > present. > > Hope I could be of help > > Zemer Margolin > > Tel: +9723-765-7571 > > E-mail: [EMAIL PROTECTED] > > > > -----Original Message----- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] Behalf Of Gustavo V. > > G. C. Rios > > Sent: Wednesday, October 29, 2003 3:28 AM > > To: [EMAIL PROTECTED] > > Subject: [ASN.1] (I AM DESPERATE, PLEASE) Beginner > > Question: ASN1 & Kerberos (rfc1510.txt) > > > > Dear gentleman, > > > > i am beginning studying ASN as an requirement for > > understanding kerberV > > security protocol. One of its message specification > > is the following: > > > > KRB-SAFE-BODY ::= [APPLICATION 20] SEQUENCE { > > user-data[0] OCTET STRING, > > timestamp[1] KerberosTime OPTIONAL, > > usec[2] INTEGER OPTIONAL, > > seq-number[3] INTEGER OPTIONAL, > > s-address[4] HostAddress, > > r-address[5] HostAddress OPTIONAL > > } > > > > My doubt regards with the decoding of the input > > stream. For the usec and > > seq-number values i have three possible scenarios: > > > > 0) The two values are present, > > 1) None of them are present, > > 2) Just one of them is present. > > > > Since both are optional and have the same type, for > > scenario 2, how will > > i *correctly* decode an input stream? I.e. , the > > next value to be decode > > is an integer, but will i see it as the usec or the > > seq-number value?
