Key derivation

General Description

Key derivation definitions.

Macros
#define	IFX_SE_KEY_DERIVATION_OPERATION_INIT   {0}
	This only zeroes out the first byte in the union, the rest is unspecified.
#define	IFX_SE_KEY_DERIVATION_INPUT_SECRET   ((ifx_se_key_derivation_step_t)0x0101)
	A secret input for key derivation. More...
#define	IFX_SE_KEY_DERIVATION_INPUT_PASSWORD   ((ifx_se_key_derivation_step_t)0x0102)
	A low-entropy secret input for password hashing / key stretching. More...
#define	IFX_SE_KEY_DERIVATION_INPUT_OTHER_SECRET    ((ifx_se_key_derivation_step_t)0x0103)
	A high-entropy additional secret input for key derivation. More...
#define	IFX_SE_KEY_DERIVATION_INPUT_LABEL   ((ifx_se_key_derivation_step_t)0x0201)
	A label for key derivation. More...
#define	IFX_SE_KEY_DERIVATION_INPUT_SALT   ((ifx_se_key_derivation_step_t)0x0202)
	A salt for key derivation. More...
#define	IFX_SE_KEY_DERIVATION_INPUT_INFO   ((ifx_se_key_derivation_step_t)0x0203)
	An information string for key derivation. More...
#define	IFX_SE_KEY_DERIVATION_INPUT_SEED   ((ifx_se_key_derivation_step_t)0x0204)
	A seed for key derivation. More...
#define	IFX_SE_KEY_DERIVATION_INPUT_COST   ((ifx_se_key_derivation_step_t)0x0205)
	A cost parameter for password hashing / key stretching. More...
#define	IFX_SE_KEY_DERIVATION_INPUT_FIXED_DATA   ((ifx_se_key_derivation_step_t)0x0206)
	Fixed data for the key derivation. More...

Typedefs
typedef struct ifx_se_key_derivation_s	ifx_se_key_derivation_operation_t
	The type of the state data structure for key derivation operations. More...
typedef uint16_t	ifx_se_key_derivation_step_t
	Encoding of the step of a key derivation.

Functions
ifx_se_status_t	ifx_se_key_derivation_abort (ifx_se_key_derivation_operation_t *operation, void *ctx)
	Abort a key derivation operation. More...
ifx_se_status_t	ifx_se_key_derivation_setup (ifx_se_key_derivation_operation_t *operation, ifx_se_alg_fih_t alg, void *ctx)
	Set up a key derivation operation. More...
ifx_se_status_t	ifx_se_key_derivation_get_capacity (const ifx_se_key_derivation_operation_t *operation, ifx_se_fih_ptr_t capacity, void *ctx)
	Retrieve the current capacity of a key derivation operation. More...
ifx_se_status_t	ifx_se_key_derivation_set_capacity (ifx_se_key_derivation_operation_t *operation, ifx_se_fih_t capacity, void *ctx)
	Set the maximum capacity of a key derivation operation. More...
ifx_se_status_t	ifx_se_key_derivation_input_key (ifx_se_key_derivation_operation_t *operation, ifx_se_key_derivation_step_t step, ifx_se_key_id_fih_t key, void *ctx)
	Provide an input for key derivation in the form of a key. More...
ifx_se_status_t	ifx_se_key_derivation_input_bytes (ifx_se_key_derivation_operation_t *operation, ifx_se_key_derivation_step_t step, const ifx_se_fih_ptr_t data, ifx_se_fih_t data_length, void *ctx)
	Provide an input for key derivation or key agreement. More...
ifx_se_status_t	ifx_se_key_derivation_output_bytes (ifx_se_key_derivation_operation_t *operation, ifx_se_fih_ptr_t output, ifx_se_fih_t output_length, void *ctx)
	Read some data from a key derivation operation. More...
ifx_se_status_t	ifx_se_key_derivation_output_key (const ifx_se_key_attributes_t *attributes, ifx_se_key_derivation_operation_t *operation, ifx_se_fih_ptr_t key, void *ctx)
	Derive a key from an ongoing key derivation operation. More...
ifx_se_status_t	ifx_se_key_derivation_key_agreement (ifx_se_key_derivation_operation_t *operation, ifx_se_key_derivation_step_t step, ifx_se_key_id_fih_t private_key, const ifx_se_fih_ptr_t peer_key, ifx_se_fih_t peer_key_length, void *ctx)
	Perform a key agreement and use the shared secret as input to a key derivation. More...
ifx_se_status_t	ifx_se_raw_key_agreement (ifx_se_alg_fih_t alg, ifx_se_key_id_fih_t private_key, const ifx_se_fih_ptr_t peer_key, ifx_se_fih_t peer_key_length, ifx_se_fih_ptr_t output, ifx_se_fih_t output_size, ifx_se_fih_ptr_t output_length, void *ctx)
	Perform a key agreement and return the raw shared secret. More...
static struct ifx_se_key_derivation_s	ifx_se_key_derivation_operation_init (void)
	Initialize the key derivation context. More...

Macro Definition Documentation

IFX_SE_KEY_DERIVATION_INPUT_SECRET

#define IFX_SE_KEY_DERIVATION_INPUT_SECRET   ((ifx_se_key_derivation_step_t)0x0101)

A secret input for key derivation.

This should be a key of type IFX_SE_KEY_TYPE_DERIVE (passed to ifx_se_key_derivation_input_key()) or the shared secret resulting from a key agreement (obtained via ifx_se_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 ifx_se_key_derivation_output_bytes(), ifx_se_key_derivation_verify_bytes(), or ifx_se_key_derivation_verify_key(), but not ifx_se_key_derivation_output_key().

IFX_SE_KEY_DERIVATION_INPUT_PASSWORD

#define IFX_SE_KEY_DERIVATION_INPUT_PASSWORD   ((ifx_se_key_derivation_step_t)0x0102)

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

This is usually a key of type IFX_SE_KEY_TYPE_PASSWORD (passed to ifx_se_key_derivation_input_key()) or a direct input (passed to ifx_se_key_derivation_input_bytes()) that is a password or passphrase. It can also be high-entropy secret such as a key of type IFX_SE_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 ifx_se_key_derivation_output_bytes(), ifx_se_key_derivation_verify_bytes(), or ifx_se_key_derivation_verify_key(), but not ifx_se_key_derivation_output_key().

IFX_SE_KEY_DERIVATION_INPUT_OTHER_SECRET

#define IFX_SE_KEY_DERIVATION_INPUT_OTHER_SECRET    ((ifx_se_key_derivation_step_t)0x0103)

A high-entropy additional secret input for key derivation.

This is typically the shared secret resulting from a key agreement obtained via ifx_se_key_derivation_key_agreement(). It may alternatively be a key of type IFX_SE_KEY_TYPE_DERIVE passed to ifx_se_key_derivation_input_key(), or a direct input passed to ifx_se_key_derivation_input_bytes().

IFX_SE_KEY_DERIVATION_INPUT_LABEL

#define IFX_SE_KEY_DERIVATION_INPUT_LABEL   ((ifx_se_key_derivation_step_t)0x0201)

A label for key derivation.

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

IFX_SE_KEY_DERIVATION_INPUT_SALT

#define IFX_SE_KEY_DERIVATION_INPUT_SALT   ((ifx_se_key_derivation_step_t)0x0202)

A salt for key derivation.

This should be a direct input. It can also be a key of type IFX_SE_KEY_TYPE_RAW_DATA or IFX_SE_KEY_TYPE_PEPPER.

IFX_SE_KEY_DERIVATION_INPUT_INFO

#define IFX_SE_KEY_DERIVATION_INPUT_INFO   ((ifx_se_key_derivation_step_t)0x0203)

An information string for key derivation.

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

IFX_SE_KEY_DERIVATION_INPUT_SEED

#define IFX_SE_KEY_DERIVATION_INPUT_SEED   ((ifx_se_key_derivation_step_t)0x0204)

A seed for key derivation.

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

IFX_SE_KEY_DERIVATION_INPUT_COST

#define IFX_SE_KEY_DERIVATION_INPUT_COST   ((ifx_se_key_derivation_step_t)0x0205)

A cost parameter for password hashing / key stretching.

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

IFX_SE_KEY_DERIVATION_INPUT_FIXED_DATA

#define IFX_SE_KEY_DERIVATION_INPUT_FIXED_DATA   ((ifx_se_key_derivation_step_t)0x0206)

Fixed data for the key derivation.

This should be a direct input.

Typedef Documentation

ifx_se_key_derivation_operation_t

typedef struct ifx_se_key_derivation_s ifx_se_key_derivation_operation_t

The type of the state data structure for key derivation operations.

This is an implementation-defined struct. Applications should not make any assumptions about the content of this structure except as directed by the documentation of a specific implementation.

Function Documentation

ifx_se_key_derivation_abort()

ifx_se_status_t ifx_se_key_derivation_abort	(	ifx_se_key_derivation_operation_t *	operation,
		void *	ctx
	)

Abort a key derivation operation.

Aborting an operation frees all associated resources except for the operation structure itself. Once aborted, the operation object can be reused for another operation by calling ifx_se_key_derivation_setup() again.

This function may be called at any time after the operation object has been initialized as described in ifx_se_key_derivation_operation_t.

In particular, it is valid to call ifx_se_key_derivation_abort() twice, or to call ifx_se_key_derivation_abort() on an operation that has not been set up.

Parameters

[in,out]	operation	The operation to abort.
[in]	ctx	The pointer to the SE syscall context that contain a special syscall data (IPC release callback etc).

Return values

IFX_SE_SUCCESS
IFX_SE_ERROR_COMMUNICATION_FAILURE
IFX_SE_ERROR_HARDWARE_FAILURE
IFX_SE_ERROR_CORRUPTION_DETECTED

ifx_se_key_derivation_setup()

ifx_se_status_t ifx_se_key_derivation_setup	(	ifx_se_key_derivation_operation_t *	operation,
		ifx_se_alg_fih_t	alg,
		void *	ctx
	)

Set up a key derivation operation.

A key derivation algorithm takes some inputs and uses them to generate a byte stream in a deterministic way. This byte stream can be used to produce keys and other cryptographic material.

To derive a key:

1. Start with an initialized object of type ifx_se_key_derivation_operation_t.
2. Call ifx_se_key_derivation_setup() to select the algorithm.
3. Provide the inputs for the key derivation by calling ifx_se_key_derivation_input_bytes() or ifx_se_key_derivation_input_key() as appropriate. Which inputs are needed, in what order, and whether they may be keys and if so of what type depends on the algorithm.
4. Optionally set the operation's maximum capacity with ifx_se_key_derivation_set_capacity(). You may do this before, in the middle of or after providing inputs. For some algorithms, this step is mandatory because the output depends on the maximum capacity.
5. To derive a key, call ifx_se_key_derivation_output_key(). To derive a byte string for a different purpose, call ifx_se_key_derivation_output_bytes(). Successive calls to these functions use successive output bytes calculated by the key derivation algorithm.
6. Clean up the key derivation operation object with ifx_se_key_derivation_abort().

If this function returns an error, the key derivation operation object is not changed.

If an error occurs at any step after a call to ifx_se_key_derivation_setup(), the operation will need to be reset by a call to ifx_se_key_derivation_abort().

Implementations must reject an attempt to derive a key of size 0.

Parameters

[in,out]	operation	The key derivation operation object to set up. It must have been initialized but not set up yet.
[in]	alg	The key derivation algorithm to compute (IFX_SE_ALG_XXX value such that IFX_SE_ALG_IS_KEY_DERIVATION(alg) is true).
[in]	ctx	The pointer to the SE syscall context that contain a special syscall data (IPC release callback etc).

Return values

IFX_SE_SUCCESS	Success.
IFX_SE_ERROR_INVALID_ARGUMENT	alg is not a key derivation algorithm.
IFX_SE_ERROR_NOT_SUPPORTED	alg is not supported or is not a key derivation algorithm.
IFX_SE_ERROR_INSUFFICIENT_MEMORY
IFX_SE_ERROR_COMMUNICATION_FAILURE
IFX_SE_ERROR_HARDWARE_FAILURE
IFX_SE_ERROR_CORRUPTION_DETECTED
IFX_SE_ERROR_STORAGE_FAILURE
IFX_SE_ERROR_BAD_STATE	The operation state is not valid (it must be inactive).

ifx_se_key_derivation_get_capacity()

ifx_se_status_t ifx_se_key_derivation_get_capacity	(	const ifx_se_key_derivation_operation_t *	operation,
		ifx_se_fih_ptr_t	capacity,
		void *	ctx
	)

Retrieve the current capacity of a key derivation operation.

The capacity of a key derivation is the maximum number of bytes that it can return. When you get N bytes of output from a key derivation operation, this reduces its capacity by N.

Parameters

[in]	operation	The operation to query.
[out]	capacity	On success, the capacity of the operation (encoded pointer to size_t variable).
[in]	ctx	The pointer to the SE syscall context that contain a special syscall data (IPC release callback etc).

Return values

IFX_SE_SUCCESS
IFX_SE_ERROR_COMMUNICATION_FAILURE
IFX_SE_ERROR_HARDWARE_FAILURE
IFX_SE_ERROR_CORRUPTION_DETECTED
IFX_SE_ERROR_BAD_STATE	The operation state is not valid (it must be active).

ifx_se_key_derivation_set_capacity()

ifx_se_status_t ifx_se_key_derivation_set_capacity	(	ifx_se_key_derivation_operation_t *	operation,
		ifx_se_fih_t	capacity,
		void *	ctx
	)

Set the maximum capacity of a key derivation operation.

The capacity of a key derivation operation is the maximum number of bytes that the key derivation operation can return from this point onwards.

Parameters

[in,out]	operation	The key derivation operation object to modify.
[in]	capacity	The new capacity of the operation. It must be less or equal to the operation's current capacity.
[in]	ctx	The pointer to the SE syscall context that contain a special syscall data (IPC release callback etc).

Return values

IFX_SE_SUCCESS
IFX_SE_ERROR_INVALID_ARGUMENT	capacity is larger than the operation's current capacity. In this case, the operation object remains valid and its capacity remains unchanged.
IFX_SE_ERROR_COMMUNICATION_FAILURE
IFX_SE_ERROR_HARDWARE_FAILURE
IFX_SE_ERROR_CORRUPTION_DETECTED
IFX_SE_ERROR_BAD_STATE	The operation state is not valid (it must be active).

ifx_se_key_derivation_input_key()

ifx_se_status_t ifx_se_key_derivation_input_key	(	ifx_se_key_derivation_operation_t *	operation,
		ifx_se_key_derivation_step_t	step,
		ifx_se_key_id_fih_t	key,
		void *	ctx
	)

Provide an input for key derivation in the form of a key.

Which inputs are required and in what order depends on the algorithm. Refer to the documentation of each key derivation or key agreement algorithm for information.

This function obtains input from a key object, which is usually correct for secret inputs or for non-secret personalization strings kept in the key store. To pass a non-secret parameter which is not in the key store, call ifx_se_key_derivation_input_bytes() instead of this function. Refer to the documentation of individual step types (IFX_SE_KEY_DERIVATION_INPUT_xxx values of type ifx_se_key_derivation_step_t) for more information.

If this function returns an error status, the operation enters an error state and must be aborted by calling ifx_se_key_derivation_abort().

Parameters

[in,out]	operation	The key derivation operation object to use. It must have been set up with ifx_se_key_derivation_setup() and must not have produced any output yet.
[in]	step	Which step the input data is for.
[in]	key	Identifier of the key. It must have an appropriate type for step and must allow the usage IFX_SE_KEY_USAGE_DERIVE or IFX_SE_KEY_USAGE_VERIFY_DERIVATION (see note) and the algorithm used by the operation.
[in]	ctx	The pointer to the SE syscall context that contain a special syscall data (IPC release callback etc).

Note

Once all inputs steps are completed, the operations will allow:

• ifx_se_key_derivation_output_bytes() if each input was either a direct input or a key with IFX_SE_KEY_USAGE_DERIVE set;
• ifx_se_key_derivation_output_key() if the input for step IFX_SE_KEY_DERIVATION_INPUT_SECRET or IFX_SE_KEY_DERIVATION_INPUT_PASSWORD was from a key slot with IFX_SE_KEY_USAGE_DERIVE and each other input was either a direct input or a key with IFX_SE_KEY_USAGE_DERIVE set;
• ifx_se_key_derivation_verify_bytes() if each input was either a direct input or a key with IFX_SE_KEY_USAGE_VERIFY_DERIVATION set;
• ifx_se_key_derivation_verify_key() under the same conditions as ifx_se_key_derivation_verify_bytes().

Return values

IFX_SE_SUCCESS	Success.
IFX_SE_ERROR_INVALID_HANDLE
IFX_SE_ERROR_NOT_PERMITTED	The key allows neither IFX_SE_KEY_USAGE_DERIVE nor IFX_SE_KEY_USAGE_VERIFY_DERIVATION, or it doesn't allow this algorithm. Also operation rejected with this response when HUK key is selected in SECURE life cycle and debug port is opened or enabled by policy.
IFX_SE_ERROR_INVALID_ARGUMENT	step is not compatible with the operation's algorithm, or step does not allow key inputs of the given type or does not allow key inputs at all.
IFX_SE_ERROR_INSUFFICIENT_MEMORY
IFX_SE_ERROR_COMMUNICATION_FAILURE
IFX_SE_ERROR_HARDWARE_FAILURE
IFX_SE_ERROR_CORRUPTION_DETECTED
IFX_SE_ERROR_STORAGE_FAILURE
IFX_SE_ERROR_BAD_STATE	The operation state is not valid for this input step.

ifx_se_key_derivation_input_bytes()

ifx_se_status_t ifx_se_key_derivation_input_bytes	(	ifx_se_key_derivation_operation_t *	operation,
		ifx_se_key_derivation_step_t	step,
		const ifx_se_fih_ptr_t	data,
		ifx_se_fih_t	data_length,
		void *	ctx
	)

Provide an input for key derivation or key agreement.

Which inputs are required and in what order depends on the algorithm. Refer to the documentation of each key derivation or key agreement algorithm for information.

This function passes direct inputs, which is usually correct for non-secret inputs. To pass a secret input, which should be in a key object, call ifx_se_key_derivation_input_key() instead of this function. Refer to the documentation of individual step types (IFX_SE_KEY_DERIVATION_INPUT_xxx values of type ifx_se_key_derivation_step_t) for more information.

If this function returns an error status, the operation enters an error state and must be aborted by calling ifx_se_key_derivation_abort().

Parameters

[in,out]	operation	The key derivation operation object to use. It must have been set up with ifx_se_key_derivation_setup() and must not have produced any output yet.
[in]	step	Which step the input data is for.
[in]	data	Input data to use (encoded pointer to input data).
[in]	data_length	Size of the data buffer in bytes (size_t).
[in]	ctx	The pointer to the SE syscall context that contain a special syscall data (IPC release callback etc).

Return values

IFX_SE_SUCCESS	Success.
IFX_SE_ERROR_INVALID_ARGUMENT	step is not compatible with the operation's algorithm, or step does not allow direct inputs.
IFX_SE_ERROR_INSUFFICIENT_MEMORY
IFX_SE_ERROR_COMMUNICATION_FAILURE
IFX_SE_ERROR_HARDWARE_FAILURE
IFX_SE_ERROR_CORRUPTION_DETECTED
IFX_SE_ERROR_STORAGE_FAILURE
IFX_SE_ERROR_BAD_STATE	The operation state is not valid for this input step.

ifx_se_key_derivation_output_bytes()

ifx_se_status_t ifx_se_key_derivation_output_bytes	(	ifx_se_key_derivation_operation_t *	operation,
		ifx_se_fih_ptr_t	output,
		ifx_se_fih_t	output_length,
		void *	ctx
	)

Read some data from a key derivation operation.

This function calculates output bytes from a key derivation algorithm and return those bytes. If you view the key derivation's output as a stream of bytes, this function destructively reads the requested number of bytes from the stream. The operation's capacity decreases by the number of bytes read.

If this function returns an error status other than IFX_SE_ERROR_INSUFFICIENT_DATA, the operation enters an error state and must be aborted by calling ifx_se_key_derivation_abort().

Parameters

[in,out]	operation	The key derivation operation object to read from.
[out]	output	Buffer where the output will be written (encoded pointer to output buffer).
[in]	output_length	Number of bytes to output.
[in]	ctx	The pointer to the SE syscall context that contain a special syscall data (IPC release callback etc).

Return values

IFX_SE_SUCCESS
IFX_SE_ERROR_NOT_PERMITTED	One of the inputs was a key whose policy didn't allow IFX_SE_KEY_USAGE_DERIVE.
IFX_SE_ERROR_INSUFFICIENT_DATA	The operation's capacity was less than output_length bytes. Note that in this case, no output is written to the output buffer. The operation's capacity is set to 0, thus subsequent calls to this function will not succeed, even with a smaller output buffer.
IFX_SE_ERROR_INSUFFICIENT_MEMORY
IFX_SE_ERROR_COMMUNICATION_FAILURE
IFX_SE_ERROR_HARDWARE_FAILURE
IFX_SE_ERROR_CORRUPTION_DETECTED
IFX_SE_ERROR_STORAGE_FAILURE
IFX_SE_ERROR_BAD_STATE	The operation state is not valid (it must be active and completed all required input steps).

ifx_se_key_derivation_output_key()

ifx_se_status_t ifx_se_key_derivation_output_key	(	const ifx_se_key_attributes_t *	attributes,
		ifx_se_key_derivation_operation_t *	operation,
		ifx_se_fih_ptr_t	key,
		void *	ctx
	)

Derive a key from an ongoing key derivation operation.

This function calculates output bytes from a key derivation algorithm and uses those bytes to generate a key deterministically. The key's location, usage policy, type and size are taken from attributes.

If you view the key derivation's output as a stream of bytes, this function destructively reads as many bytes as required from the stream. The operation's capacity decreases by the number of bytes read.

If this function returns an error status other than IFX_SE_ERROR_INSUFFICIENT_DATA, the operation enters an error state and must be aborted by calling ifx_se_key_derivation_abort().

How much output is produced and consumed from the operation, and how the key is derived, depends on the key type and on the key size (denoted bits below):

• For key types for which the key is an arbitrary sequence of bytes of a given size, this function is functionally equivalent to calling ifx_se_key_derivation_output_bytes and passing the resulting output to ifx_se_import_key. However, this function has a security benefit: if the implementation provides an isolation boundary then the key material is not exposed outside the isolation boundary. As a consequence, for these key types, this function always consumes exactly (bits / 8) bytes from the operation. The following key types defined in this specification follow this scheme:
  • IFX_SE_KEY_TYPE_AES;
  • IFX_SE_KEY_TYPE_ARIA;
  • IFX_SE_KEY_TYPE_CAMELLIA;
  • IFX_SE_KEY_TYPE_DERIVE;
  • IFX_SE_KEY_TYPE_HMAC;
  • IFX_SE_KEY_TYPE_PASSWORD_HASH.
• For ECC keys on a Montgomery elliptic curve (IFX_SE_KEY_TYPE_ECC_KEY_PAIR(curve) where curve designates a Montgomery curve), this function always draws a byte string whose length is determined by the curve, and sets the mandatory bits accordingly. That is:
  • Curve25519 (IFX_SE_ECC_FAMILY_MONTGOMERY, 255 bits): draw a 32-byte string and process it as specified in RFC 7748 §5.
  • Curve448 (IFX_SE_ECC_FAMILY_MONTGOMERY, 448 bits): draw a 56-byte string and process it as specified in RFC 7748 §5.
• For key types for which the key is represented by a single sequence of bits bits with constraints as to which bit sequences are acceptable, this function draws a byte string of length (bits / 8) bytes rounded up to the nearest whole number of bytes. If the resulting byte string is acceptable, it becomes the key, otherwise the drawn bytes are discarded. This process is repeated until an acceptable byte string is drawn. The byte string drawn from the operation is interpreted as specified for the output produced by ifx_se_export_key(). The following key types defined in this specification follow this scheme:
  • IFX_SE_KEY_TYPE_DES. Force-set the parity bits, but discard forbidden weak keys. For 2-key and 3-key triple-DES, the three keys are generated successively (for example, for 3-key triple-DES, if the first 8 bytes specify a weak key and the next 8 bytes do not, discard the first 8 bytes, use the next 8 bytes as the first key, and continue reading output from the operation to derive the other two keys).
  • Finite-field Diffie-Hellman keys (IFX_SE_KEY_TYPE_DH_KEY_PAIR(group) where group designates any Diffie-Hellman group) and ECC keys on a Weierstrass elliptic curve (IFX_SE_KEY_TYPE_ECC_KEY_PAIR(curve) where curve designates a Weierstrass curve). For these key types, interpret the byte string as integer in big-endian order. Discard it if it is not in the range [0, N - 2] where N is the boundary of the private key domain (the prime p for Diffie-Hellman, the subprime q for DSA, or the order of the curve's base point for ECC). Add 1 to the resulting integer and use this as the private key x. This method allows compliance to NIST standards, specifically the methods titled "key-pair generation by testing candidates" in NIST SP 800-56A §5.6.1.1.4 for Diffie-Hellman, in FIPS 186-4 §B.1.2 for DSA, and in NIST SP 800-56A §5.6.1.2.2 or FIPS 186-4 §B.4.2 for elliptic curve keys.
• For other key types, including IFX_SE_KEY_TYPE_RSA_KEY_PAIR, the way in which the operation output is consumed is implementation-defined.

In all cases, the data that is read is discarded from the operation. The operation's capacity is decreased by the number of bytes read.

For algorithms that take an input step IFX_SE_KEY_DERIVATION_INPUT_SECRET, the input to that step must be provided with ifx_se_key_derivation_input_key(). Future versions of this specification may include additional restrictions on the derived key based on the attributes and strength of the secret key.

Parameters

[in]	attributes	The attributes for the new key. If the key type to be created is IFX_SE_KEY_TYPE_PASSWORD_HASH then the algorithm in the policy must be the same as in the current operation.
[in,out]	operation	The key derivation operation object to read from.
[out]	key	On success, an identifier for the newly created key (encoded pointer to ifx_se_key_id_fih_t variable). For persistent keys, this is the key identifier defined in attributes. 0 on failure.
[in]	ctx	The pointer to the SE syscall context that contain a special syscall data (IPC release callback etc).

Return values

IFX_SE_SUCCESS	Success. If the key is persistent, the key material and the key's metadata have been saved to persistent storage.
IFX_SE_ERROR_ALREADY_EXISTS	This is an attempt to create a persistent key, and there is already a persistent key with the given identifier.
IFX_SE_ERROR_INSUFFICIENT_DATA	There was not enough data to create the desired key. Note that in this case, no output is written to the output buffer. The operation's capacity is set to 0, thus subsequent calls to this function will not succeed, even with a smaller output buffer.
IFX_SE_ERROR_NOT_SUPPORTED	The key type or key size is not supported, either by the implementation in general or in this particular location.
IFX_SE_ERROR_INVALID_ARGUMENT	The provided key attributes are not valid for the operation.
IFX_SE_ERROR_NOT_PERMITTED	The IFX_SE_KEY_DERIVATION_INPUT_SECRET or IFX_SE_KEY_DERIVATION_INPUT_PASSWORD input was not provided through a key; or one of the inputs was a key whose policy didn't allow IFX_SE_KEY_USAGE_DERIVE.
IFX_SE_ERROR_INSUFFICIENT_MEMORY
IFX_SE_ERROR_INSUFFICIENT_STORAGE
IFX_SE_ERROR_COMMUNICATION_FAILURE
IFX_SE_ERROR_HARDWARE_FAILURE
IFX_SE_ERROR_CORRUPTION_DETECTED
IFX_SE_ERROR_DATA_INVALID
IFX_SE_ERROR_DATA_CORRUPT
IFX_SE_ERROR_STORAGE_FAILURE
IFX_SE_ERROR_BAD_STATE	The operation state is not valid (it must be active and completed all required input steps).

ifx_se_key_derivation_key_agreement()

ifx_se_status_t ifx_se_key_derivation_key_agreement	(	ifx_se_key_derivation_operation_t *	operation,
		ifx_se_key_derivation_step_t	step,
		ifx_se_key_id_fih_t	private_key,
		const ifx_se_fih_ptr_t	peer_key,
		ifx_se_fih_t	peer_key_length,
		void *	ctx
	)

Perform a key agreement and use the shared secret as input to a key derivation.

A key agreement algorithm takes two inputs: a private key private_key a public key peer_key. The result of this function is passed as input to a key derivation. The output of this key derivation can be extracted by reading from the resulting operation to produce keys and other cryptographic material.

If this function returns an error status, the operation enters an error state and must be aborted by calling ifx_se_key_derivation_abort().

Parameters

[in,out]	operation	The key derivation operation object to use. It must have been set up with ifx_se_key_derivation_setup() with a key agreement and derivation algorithm alg (IFX_SE_ALG_XXX value such that IFX_SE_ALG_IS_KEY_AGREEMENT(alg) is true and IFX_SE_ALG_IS_RAW_KEY_AGREEMENT(alg) is false). The operation must be ready for an input of the type given by step.
[in]	step	Which step the input data is for.
[in]	private_key	Identifier of the private key to use. It must allow the usage IFX_SE_KEY_USAGE_DERIVE.
[in]	peer_key	Public key of the peer (encoded pointer to input data). The peer key must be in the same format that ifx_se_import_key() accepts for the public key type corresponding to the type of private_key. That is, this function performs the equivalent of ifx_se_import_key(..., peer_key, peer_key_length) where with key attributes indicating the public key type corresponding to the type of private_key. For example, for EC keys, this means that peer_key is interpreted as a point on the curve that the private key is on. The standard formats for public keys are documented in the documentation of ifx_se_export_public_key().
[in]	peer_key_length	Size of peer_key in bytes (size_t).
[in]	ctx	The pointer to the SE syscall context that contain a special syscall data (IPC release callback etc).

Return values

IFX_SE_SUCCESS	Success.
IFX_SE_ERROR_INVALID_HANDLE
IFX_SE_ERROR_NOT_PERMITTED
IFX_SE_ERROR_INVALID_ARGUMENT	private_key is not compatible with alg, or peer_key is not valid for alg or not compatible with private_key, or step does not allow an input resulting from a key agreement.
IFX_SE_ERROR_NOT_SUPPORTED	alg is not supported or is not a key derivation algorithm.
IFX_SE_ERROR_INSUFFICIENT_MEMORY
IFX_SE_ERROR_COMMUNICATION_FAILURE
IFX_SE_ERROR_HARDWARE_FAILURE
IFX_SE_ERROR_CORRUPTION_DETECTED
IFX_SE_ERROR_STORAGE_FAILURE
IFX_SE_ERROR_BAD_STATE	The operation state is not valid for this key agreement step, or the library has not been previously initialized by ifx_se_crypto_init(). It is implementation-dependent whether a failure to initialize results in this error code.

ifx_se_raw_key_agreement()

ifx_se_status_t ifx_se_raw_key_agreement	(	ifx_se_alg_fih_t	alg,
		ifx_se_key_id_fih_t	private_key,
		const ifx_se_fih_ptr_t	peer_key,
		ifx_se_fih_t	peer_key_length,
		ifx_se_fih_ptr_t	output,
		ifx_se_fih_t	output_size,
		ifx_se_fih_ptr_t	output_length,
		void *	ctx
	)

Perform a key agreement and return the raw shared secret.

Warning

The raw result of a key agreement algorithm such as finite-field Diffie-Hellman or elliptic curve Diffie-Hellman has biases and should not be used directly as key material. It should instead be passed as input to a key derivation algorithm. To chain a key agreement with a key derivation, use ifx_se_key_derivation_key_agreement() and other functions from the key derivation interface.

Parameters

	alg	The key agreement algorithm to compute (IFX_SE_ALG_XXX value such that IFX_SE_ALG_IS_RAW_KEY_AGREEMENT(alg) is true).
[in]	private_key	Identifier of the private key to use. It must allow the usage IFX_SE_KEY_USAGE_DERIVE.
[in]	peer_key	Public key of the peer (encoded pointer to input data). It must be in the same format that ifx_se_import_key() accepts. The standard formats for public keys are documented in the documentation of ifx_se_export_public_key().
[in]	peer_key_length	Size of peer_key in bytes (size_t).
[out]	output	Buffer where the raw shared secret is to be written (encoded pointer to output buffer).
[in]	output_size	Size of the output buffer in bytes (size_t).
[out]	output_length	On success, the number of bytes that make up the returned output (encoded pointer to size_t variable).
[in]	ctx	The pointer to the SE syscall context that contain a special syscall data (IPC release callback etc).

Return values

IFX_SE_SUCCESS	Success.
IFX_SE_ERROR_INVALID_HANDLE
IFX_SE_ERROR_NOT_PERMITTED
IFX_SE_ERROR_INVALID_ARGUMENT	alg is not a key agreement algorithm, or private_key is not compatible with alg, or peer_key is not valid for alg or not compatible with private_key.
IFX_SE_ERROR_BUFFER_TOO_SMALL	output_size is too small
IFX_SE_ERROR_NOT_SUPPORTED	alg is not a supported key agreement algorithm.
IFX_SE_ERROR_INSUFFICIENT_MEMORY
IFX_SE_ERROR_COMMUNICATION_FAILURE
IFX_SE_ERROR_HARDWARE_FAILURE
IFX_SE_ERROR_CORRUPTION_DETECTED
IFX_SE_ERROR_STORAGE_FAILURE
IFX_SE_ERROR_BAD_STATE	The library has not been previously initialized by ifx_se_crypto_init(). It is implementation-dependent whether a failure to initialize results in this error code.

ifx_se_key_derivation_operation_init()

static struct ifx_se_key_derivation_s ifx_se_key_derivation_operation_init ( void  )

inlinestatic

Initialize the key derivation context.

Returns

ifx_se_key_derivation_s structure