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?
