Abstract Syntax Notation One (ASN1) is a notation method for defining data types and structures. Within the ASN1 specification are the encoding and decoding rules for those data types and structures so that applications can exchange data. Some of the Internet's most common protocols use ASN1 to describe their syntax; LDAP, SMNP, H323 and SSL.

The Boost.ASN1 is a cross-platform library that offers encoding and decoding functionality according to the specification described in ITU-T international standards X.680 and X.691:

- Basic Encoding Rules (BER)
- Distinguished Encoding Rules (DER)
- Canonical Encoding Rules (CER)
- Packed Encoding Rules (PER)

This library does not parse ASN1 files to create C++ structures as some other libraries do. This library is designed to be used directly with an easy to use set of classes and templates.