Computer Dictionary of Information Technology

Distinguished Encoding Rules

(DER) An X.690 encoding format (or transfer syntax) for data structures described by ASN.1 that specifies exactly one way to encode a value thus ensuring a unique, canonical, serialised representation. DER is a restricted variant of BER. For example, DER has exactly one way to encode a Boolean value. DER is used in cryptography, e.g. for digital certificates such as X.509.