Key derivation

A secret input for key derivation.

This should be a key of type PSA_KEY_TYPE_DERIVE (passed to psa_key_derivation_input_key() ) or the shared secret resulting from a key agreement (obtained via psa_key_derivation_key_agreement() ).

The secret can also be a direct input (passed to key_derivation_input_bytes()). In this case, the derivation operation may not be used to derive keys: the operation will only allow psa_key_derivation_output_bytes() , psa_key_derivation_verify_bytes() , or psa_key_derivation_verify_key() , but not psa_key_derivation_output_key() .

A low-entropy secret input for password hashing / key stretching.

This is usually a key of type PSA_KEY_TYPE_PASSWORD (passed to psa_key_derivation_input_key() ) or a direct input (passed to psa_key_derivation_input_bytes() ) that is a password or passphrase. It can also be high-entropy secret such as a key of type PSA_KEY_TYPE_DERIVE or the shared secret resulting from a key agreement.

The secret can also be a direct input (passed to key_derivation_input_bytes()). In this case, the derivation operation may not be used to derive keys: the operation will only allow psa_key_derivation_output_bytes() , psa_key_derivation_verify_bytes() , or psa_key_derivation_verify_key() , but not psa_key_derivation_output_key() .

A high-entropy additional secret input for key derivation.

This is typically the shared secret resulting from a key agreement obtained via psa_key_derivation_key_agreement() . It may alternatively be a key of type PSA_KEY_TYPE_DERIVE passed to psa_key_derivation_input_key() , or a direct input passed to psa_key_derivation_input_bytes() .

A label for key derivation.

This should be a direct input. It can also be a key of type PSA_KEY_TYPE_RAW_DATA .

A salt for key derivation.

This should be a direct input. It can also be a key of type PSA_KEY_TYPE_RAW_DATA or PSA_KEY_TYPE_PEPPER .

An information string for key derivation.

This should be a direct input. It can also be a key of type PSA_KEY_TYPE_RAW_DATA .

A seed for key derivation.

This should be a direct input. It can also be a key of type PSA_KEY_TYPE_RAW_DATA .

A cost parameter for password hashing / key stretching.

This must be a direct input, passed to psa_key_derivation_input_integer() .

Encoding of the step of a key derivation.

Values of this type are generally constructed by macros called PSA_KEY_DERIVATION_INPUT_xxx .