信息技术 ASN.1编码规则:基本编码规则(BER)、典型编码规则(CER)和区分编码规则(DER)的规范

[中文适用范围]： 此建议|国际标准规定了一组基本编码规则，这些规则可用于导出使用 ITU-T Rec.1 中规定的符号定义的类型值的传输语法规范。 X.680 | ISO/IEC 8824-1、ITU-T 建议书。 X.681 | ISO/IEC 8824-2、ITU-T 建议书。 X.682 | ISO/IEC 8824-3 和 ITU-T Rec. X.683 | ISO/IEC 8824-4，统称为抽象语法表示法一或 ASN.l。 这些基本编码规则也适用于对这种传输语法进行解码，以便识别正在传输的数据值。 它还指定了一组规范且独特的编码规则，这些规则将值的编码限制为基本编码规则提供的替代方案之一。 [外文原描述]： ISO/IEC 8825-1:2002 defines a set of Basic Encoding Rules (BER) that may be applied to values of types defined using the ASN.1 notation. Application of these encoding rules produces a transfer syntax for such values. It is implicit in the specification of these encoding rules that they are also used for decoding. ISO/IEC 8825-1:2002 defines also a set of Distinguished Encoding Rules (DER) and a set of Canonical Encoding Rules (CER) both of which provide constraints on the Basic Encoding Rules (BER). The key difference between them is that DER uses the definite length form of encoding while CER uses the indefinite length form. DER is more suitable for the small encoded values, while CER is more suitable for the large ones. It is implicit in the specification of these encoding rules that they are also used for decoding.