Canonical Encoding Rules
<protocol, standard> (CER) A restricted variant of
BER for producing unequivocal
transfer syntax for data structures described by
ASN.1.
Whereas
BER gives choices as to how data values may be encoded, CER and
DER select just one encoding from those allowed by the basic encoding rules, eliminating all of the options.
They are useful when the encodings must be preserved, e.g. in security exchanges.
CER and
DER differ in the set of restrictions that they place on the encoder.
The basic difference between CER and
DER is that
DER uses definitive length form and CER uses indefinite length form.
Documents:
ITU-T X.690,
ISO 8825-1.
See also
PER.
