X.690

Common card · No. 407030

X.690 is an ITU-T standard specifying several ASN.1 encoding formats: Basic Encoding Rules (BER) Canonical Encoding Rules (CER) Distinguished Encoding Rules (DER) The Basic Encoding Rules (BER) were the original rules laid out by the ASN.1 standard for encoding data into a binary format. The rules, collectively referred to as a transfer syntax in ASN.1 parlance, specify the exact octets (8-bit bytes) used to encode data. X.680 defines a syntax for declaring data types, for example: Booleans, numbers, strings, and compound structures. Each type definition also includes an identifying number. X.680 defines several primitive data types, for example: BooleanType, IntegerType, OctetStringType. (ASN.1 also provides for constructed types built from other types.) Types are associated with a class. For example, the primitive types are part of the universal class. The three other classes (application, private, and context-specific) are essentially different scopes to support customization...

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