Crypto Key Derive

This MotoHawk™ block is part of the Cryptography Blockset and performs a key derivation operation using the key material referenced in the associated Crypto Key Definition.

Block ID

Crypto Key Derive

Library

motohawk_crypto_lib

Description

This MotoHawk™ block is part of the Cryptography Blockset and performs a key derivation operation using the key material referenced in the associated Crypto Key Definition.

There may be a number of supported derivation functions. The input port configuration are specific to a particular derivation function. The derivation function will use the input port key material combined with the referenced key to produce a new key. The dimension of the new key will be the same as the referenced key.

HKDF

The HKDF is a simple key derivation function based on the HMAC authentication code. Details can be found in RFC5869. The HKDF uses an input 'Salt' vector combined with an additional 'Info' vector which combined with the shared secret key (i.e. the referenced key) to produce a new key.

HKDF Input Ports

Salt[] (uint8)

An array of salt data to feed the HKDF derivation function. The vector size is determined by the selected length in the block mask 'Salt Length' parameter.

Info[] (uint8)

An array of info data to feed the HKDF derivation function. The vector size is determined by the selected length in the block mask 'Info Length' parameter.

HKDF Output Ports

DerivedKey[N] (uint8)

The derived key which is computed from the referenced key material in combination with the input data. Note that the dimension of the array is determined by the key type.

Block Parameters

Parameter Field	Values	Comments/Description
Crypto Key Source	Single quote enclosed c-legal alpha-numeric text	The name of the associated Crypto Key Definition.
Derivation Function	Drop down	The selected derivation function. Block mask parameters, input ports and output ports may be reconfigured depending on this selection.
Salt Length	Positive integer	Visible when the derived key HKDF algorithm is selected. This defines the length of the salt data expected at the Salt input port.
Info Length	Positive integer	Visible when the derived key HKDF algorithm is selected. This defines the length of the info data expected at the Info input port.