Packed Encoding Rules

Protocol developers define data structures in ASN.1 modules, which are generally a section of a broader standards document written in the ASN.1 language. The advantage is that the ASN.1 description of the data encoding is independent of a particular computer or programming language (other than ASN.1.) Because ASN.1 is both human-readable and machine-readable, an ASN.1 compiler can compile modules into libraries of code, CODECs, that decode or encode the data structures. Some ASN.1 compilers can produce code to encode or decode several encodings, e.g. packed, BER or XML. ASN.1 is a joint standard of the International Telecommunication Union Telecommunication Standardization Sector (ITU-T) and ISO/IEC, originally defined in 1984 as part of CCITT X.409:1984. In 1988, ASN.1 moved to its own standard, X.208, due to wide applicability. The substantially revised 1995 version is covered by the X.680 series . The latest revision of the X.680 series of recommendations is the 5.0 Edition, published in 2015. ASN.1 is a data type declaration notation. It does not define how to manipulate a variable of such a type. This is actually defined in other languages such as SDL (Specification and Description Language) for executable modeling or TTCN-3 (Testing and Test Control Notation) for conformance testing. Both these languages natively support ASN.1 declarations. It is possible to import an ASN.1 module and declare variable of any of the ASN.1 types declared in the module. ASN.1 is used in very diverse applications such as parcel tracking, power distribution and biomedicine. Its most extensive use continues to be in standard telecommunication protocols such as Intelligent networks, UMTS, Voice over IP, Interactive television and HiperAccess. ASN.1 is used in X.509, which defines the format of certificates used in the HTTPS protocol for securely browsing the web, and in many other cryptographic systems. It's also used in the PKCS group of cryptography standards, X.400 electronic mail, X.500 and Lightweight Directory Access Protocol (LDAP), H.323 (VoIP), Kerberos, BACnet, Simple Network Management Protocol (SNMP), and third- and fourth-generation wireless communications technologies (UMTS, LTE, and WiMAX 2).