Hi there, In section 4.1, just after your use of the deprecated "ANY" notation, your profile states incorrectly that "DER is defined in [X.208-88]". X.208 defines Abstract Syntax Notation ONE (ASN.1), but it does not define any of the ASN.1 encoding rules. Way back in 1988, the time period to which you refer, the ASN.1 encoding rules were defined in X.209. Of course both X.208 and X.209 have been superseded and relegated along with their lists of unresolved defects to the maintenance site, at http://www.furniss.co.uk/maint/asn/index.html. In 1988, only BER existed as an ASN.1 standard, as defined in X.209 (though X.509:88 defined a set of restrictions on X.209 that they called DER). The DER, PER and CER encoding rules were not standardized until 1994. It could be that you are referring to "[X.509-88]" in your document rather than the current version of X.509 (which defines ACs) to try to include some sort of DER support for X.208/209 - hard to tell. The initial DER was created by Hoyt Kesterson's X.509 group. Out of their efforts, the ASN.1 DER rules evolved, and are now defined in the current ASN.1 standard, X.690. Though the spirit of X.509-88 and X.690:DER are the same, X.690:DER corrects a number of oversights present in X.509-88. These two rule sets differ in slight ways, particularly in how bit string values and a few other very small details are handled. These distinctions become important when digital signatures are involved. A good description of DER can be found in a free download copy of the recent ASN.1 book by John Larmouth, called ASN.1 Complete, at http://www.nokalva.com/asn1/booksintro.html. Hard copy is also available from B&N (not for free I think). All of the wrinkles and warts are discussed. Worth a read if you have to deal often with such things. Phil ---- Phillip H. Griffin Griffin Consulting http://asn-1.com Secure ASN.1 Design & Implementation +1-919-832-7008 1625 Glenwood Avenue, Five Points +1-919-832-7390 [fax] Raleigh, North Carolina 27608 USA ------------------------------------------------------------