Crate simple_tlv

simple-tlv

Implementation of the SIMPLE-TLV serialization format from ISO 7816-4:2005.

5.2.1 SIMPLE-TLV data objects

Each SIMPLE-TLV data object shall consist of two or three consecutive fields: a mandatory tag field, a mandatory length field and a conditional value field. A record (see 7.3.1) may be a SIMPLE-TLV data object.

• The tag field consists of a single byte encoding a tag number from 1 to 254. The values '00' and 'FF' are invalid for tag fields. If a record is a SIMPLE-TLV data object, then the tag may be used as record identifier.
• The length field consists of one or three consecutive bytes.
  • If the first byte is not set to 'FF', then the length field consists of a single byte encoding a number from zero to 254 and denoted N.
  • If the first byte is set to 'FF', then the length field continues on the subsequent two bytes with any value encoding a number from zero to 65,535 and denoted N.
• If N is zero, there is no value field, i.e., the data object is empty. Otherwise (N > 0), the value field consists of N consecutive bytes.

Credits

This library is a remix of RustCrypto/utils/der, with a view towards:

• not requiring references to ASN.1 (e.g., since SIMPLE-TLV does not have any)
• not requiring allocations or memmoves (like ring, derp, x509:der)
• adding a type layer on top of SIMPLE-TLV's byte slice values

The core idea taken from der is to have Encodable require an encoded_length method. By calling this recursively in a first pass, allocations required in other approaches are avoided.

Structs

Decoder	SIMPLE-TLV decoder.
Encoder	SIMPLE-TLV encoder.
Error	Error type.
Length	SIMPLE-TLV-encoded length.
Slice	Slice of at most Length::max() bytes.
Tag	The tag field consists of a single byte encoding a tag number from 1 to 254. The values '00' and 'FF' are invalid.
TaggedValue	SIMPLE-TLV data object.

Enums

ErrorKind

Error type.

Traits

Container	Multiple encodables in a container.
Decodable	Decoding trait.
Encodable	Encoding trait.
Tagged	Types with an associated SIMPLE-TLV Tag.

Type Definitions

Result	Result type.
TaggedSlice	Raw SIMPLE-TLV data object TaggedValue<Slice<'_>>.

Derive Macros

Decodable	Derive the Decodable trait on a struct.
Encodable	Derive the Encodable trait on a struct.