Class desfire::protocol

Inheritance Relationships

Derived Types

Class Documentation

class protocol

Class capturing the secure communication mode over some cryptographic primitive (crypto).

A protocol instance is responsible to secure the data for transmission and decode it in reception. It works by operating a crypto object in an appropriate way; in general, it is a stateful object.

See also

Currently only two implementations are relevant:

Subclassed by desfire::protocol_default, desfire::protocol_dummy, desfire::protocol_legacy

Public Functions

virtual void prepare_tx(bin_data &data, std::size_t offset, comm_mode mode) = 0

Prepares data for transmission. This method is responsible for securing, in-place, all data starting at offset using the specified mode.

Parameters:

  • data – Data to secure; it is modified in-place.

  • offset – Offset in data of the sensitive data.

  • mode – Mode in which to operate the underlying crypto.

virtual bool confirm_rx(bin_data &data, comm_mode mode) = 0

Post-processes data after reception.

Parameters:

  • data – Received data. The data must include a bits::status byte, which must come last in this sequence. The caller is responsible for shifting it to the last position. The data is modified in-place.

  • mode – Mode in which to operate the underlying crypto.

Returns:

A boolean representing whether data was successfully validated. A return value of false indicates invalid MAC, invalid key, or session, or invalid mode, or any unlikely but possible attempt of tampering.

virtual void init_session(bin_data const &random_data) = 0

Sets up the session symmetric key used for further communication. This is the first operation that follows a successful authentication. This method calls crypto::init_session with random_data.

Parameters:

random_data – Random data obtained via key exchange

virtual bool is_legacy() const = 0

A boolean indicating whether this class uses a legacy scheme.

Note

Currently there are only two schemes, protocol_legacy and protocol_default, so this is just a way to know whether it is legacy or not.

virtual ~protocol() = default