2019-06-06 [read as txt or PDF]

Abstract Syntax Notation One (ASN.1) allows defining data structures that can be serialized and deserialized in a cross-platform way.

Basic Encoding Rules (BER) specify a self-describing and self-delimiting format for encoding ASN.1 data structures.

Distinguished Encoding Rules (DER) is a restricted variant of BER thas is unequivocal.

DER is a tag-length-value (TLV) encoding:

Class encodings:

Class Bit 8 Bit 7
universal 0 0
application 0 1
context-specific 1 0
private 1 1