JAC (Java Asn1 Compiler) is a tool for you if you want to (1)parse your asn1 file (2)create .java classes and (3)encode/decode instances of your classes. Just forget all asn1 byte streams, and take the advantage of OOP! BER, CER and DER are all supported
Toolset for the TMPL (Template Matching Processor Language). Compiler and runtime for creating/ evaluating templates on XML data streams. Can be integrated easily in Java projects.