TLVencoded

TLV encoding stands for Tag-Length-Value, a data encoding method in which each data element is encoded as a triplet: a tag that identifies the data type, a length that specifies the size of the value, and a value that contains the data bytes. The method is commonly referred to as TLV encoding or TLV-encoded data.

The tag conveys information about the element's type and encoding rules. It may specify a class (universal, application, context-specific, private) and indicate whether the element is primitive or constructed, and it may also carry a tag number that further identifies the item. The length field encodes how many octets follow in the value. Length can be encoded in a short form for small values or a long form for larger ones; some protocols also allow an indefinite form for streaming data.

TLV is used in many standards and applications, notably ASN.1 BER/DER encodings, ISO 7816 smart cards, NFC data formats such as NDEF, and various cryptographic structures. This encoding supports nested data by allowing a value to itself contain TLV-encoded data.

A simple example is a universal, primitive integer tag 0x02 with length 0x01 and value 0x05, representing the number 5. Another example is 0x16 (IA5String) with length 0x04 and value "test". The flexibility and self-describing nature of TLV encoding make it a common choice for data interchange and storage across diverse domains.