1.Q: Is it possible to build the asn1c compiler on Win32? 1.A: At this point, the asn1c source code is tied to GCC-specific extensions in several key places. The CYGWIN environment with gcc compiler may be what are you looking for. Please also consider using the Online ASN.1 compiler at http://lionet.info/asn1c which generates platform-independent code. 2.Q: How to build a simplest BER (XER) encoder or decoder? 2.A: Please check the "Quick Start Guide" on ./doc/asn1c-quick.pdf Please check the "Examples" section of ./doc/asn1c-usage.pdf Also, try the following to build the X.509v3 parser: cd ./examples/sample.source.PKIX1 make ./x509dump -h 3.Q: Your compiler supplies a der_encode() procedure. How do I encode BER? 3.A: The DER (and CER) are stricter subsets of a more generic BER encoding method. If you encode data with DER or CER, all BER-conformant decoders will easily understand that. Hence, to encode data in the BER format, simply use the DER encoder, der_encode(). See also: ISO/IEC 8825-1 / X.690: "ASN.1 encoding rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER)" -- Lev Walkin vlm@lionet.info