Embedded systems programmers must handle an increasing number of protocols, specified in many syntaxes (XML, XDR). Protocols that were handled on larger network devices, such as X.509, VoIP, WAP, and SSLare, are increasingly moving into the embedded space. Many of these protocols are specified in Abstract Syntax Notation (ASN.1).

This paper will present options that the embedded systems programmer may use to incorporate ASN.1 handling that permits interoperability and efficiency. In particular, experiences in handling X.509 certificates using DER on constrained devices will be used to illustrate the concepts discussed.