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Learn about the Basic Encoding Rules (BER) specified by the ASN.1 standard for encoding abstract information into concrete data streams using TLV encodings. Includes examples of BER encoding for two's complement integers and object identifiers.
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CITA 440 Week 4 BER
BER and TLV • The Basic Encoding Rules (BER) were the original rules laid out by the ASN.1 standard for encoding abstract information into a concrete data stream. The rules, collectively referred to as a transfer syntax in ASN.1 parlance, specify the exact octet sequences which are used to encode a given data item. • In BER, each data element is normally encoded as a type identifier (T), a length description (L), and the actual data element content value (V). These types of encodings are commonly called type-length-value or TLV encodings. • The most common BER format is encoding through octet values in hexadecimal.
Tag (Used in Identifier Field) • Tag uniquely identifies a data type • Comprises class and tag number • Class: • Universal • Application • Context-specific • Private (used extensively by commercial vendors)