The type of the state data structure for multipart MAC operations.

Before calling any function on a MAC operation object, the application must initialize it by any of the following means:

• Set the structure to all-bits-zero, for example:
  1 psa_mac_operation_t operation;

  2 memset(&operation, 0, sizeof(operation));
• Initialize the structure to logical zero values, for example:
  1 psa_mac_operation_t operation = {0};
• Initialize the structure to the initializer #PSA_MAC_OPERATION_INIT, for example:
  1 psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT;
• Assign the result of the function psa_mac_operation_init() to the structure, for example:
  1 psa_mac_operation_t operation;

  2 operation = psa_mac_operation_init();

This is an implementation-defined struct. Applications should not make any assumptions about the content of this structure. Implementation details can change in future versions without notice.

Definition at line 1258 of file TARGET_TFM/TARGET_TFM_LATEST/include/psa/crypto.h.

The type of the state data structure for multipart MAC operations.

Before calling any function on a MAC operation object, the application must initialize it by any of the following means:

• Set the structure to all-bits-zero, for example:
  1 psa_mac_operation_t operation;

  2 memset(&operation, 0, sizeof(operation));
• Initialize the structure to logical zero values, for example:
  1 psa_mac_operation_t operation = {0};
• Initialize the structure to the initializer #PSA_MAC_OPERATION_INIT, for example:
  1 psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT;
• Assign the result of the function psa_mac_operation_init() to the structure, for example:
  1 psa_mac_operation_t operation;

  2 operation = psa_mac_operation_init();

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.

Definition at line 1284 of file TARGET_MBED_PSA_SRV/inc/psa/crypto.h.

The type of the state data structure for multipart MAC operations.

Before calling any function on a MAC operation object, the application must initialize it by any of the following means:

• Set the structure to all-bits-zero, for example:
  1 psa_mac_operation_t operation;

  2 memset(&operation, 0, sizeof(operation));
• Initialize the structure to logical zero values, for example:
  1 psa_mac_operation_t operation = {0};
• Initialize the structure to the initializer #PSA_MAC_OPERATION_INIT, for example:
  1 psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT;
• Assign the result of the function psa_mac_operation_init() to the structure, for example:
  1 psa_mac_operation_t operation;

  2 operation = psa_mac_operation_init();

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.

Definition at line 1323 of file TARGET_TFM/TARGET_TFM_V1_0/include/psa/crypto.h.

Abort a MAC 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 psa_mac_sign_setup() or psa_mac_verify_setup() again.

You may call this function any time after the operation object has been initialized by one of the methods described in psa_mac_operation_t.

In particular, calling psa_mac_abort() after the operation has been terminated by a call to psa_mac_abort(), psa_mac_sign_finish() or psa_mac_verify_finish() is safe and has no effect.

Parameters

[in,out]

operation

Initialized MAC operation.

Return values

PSA_SUCCESS
PSA_ERROR_COMMUNICATION_FAILURE
PSA_ERROR_HARDWARE_FAILURE
PSA_ERROR_CORRUPTION_DETECTED
PSA_ERROR_BAD_STATE	The library has not been previously initialized by psa_crypto_init(). It is implementation-dependent whether a failure to initialize results in this error code.

Calculate the MAC (message authentication code) of a message.

Note

To verify the MAC of a message against an expected value, use psa_mac_verify() instead. Beware that comparing integrity or authenticity data such as MAC values with a function such as memcmp is risky because the time taken by the comparison may leak information about the MAC value which could allow an attacker to guess a valid MAC and thereby bypass security controls.

Parameters

	key	Identifier of the key to use for the operation. It must allow the usage PSA_KEY_USAGE_SIGN_MESSAGE.
	alg	The MAC algorithm to compute (PSA_ALG_XXX value such that PSA_ALG_IS_MAC(alg) is true).
[in]	input	Buffer containing the input message.
	input_length	Size of the input buffer in bytes.
[out]	mac	Buffer where the MAC value is to be written.
	mac_size	Size of the mac buffer in bytes.
[out]	mac_length	On success, the number of bytes that make up the MAC value.

Return values

PSA_SUCCESS	Success.
PSA_ERROR_INVALID_HANDLE
PSA_ERROR_NOT_PERMITTED
PSA_ERROR_INVALID_ARGUMENT	key is not compatible with alg.
PSA_ERROR_NOT_SUPPORTED	alg is not supported or is not a MAC algorithm.
PSA_ERROR_BUFFER_TOO_SMALL	mac_size is too small
PSA_ERROR_INSUFFICIENT_MEMORY
PSA_ERROR_COMMUNICATION_FAILURE
PSA_ERROR_HARDWARE_FAILURE
PSA_ERROR_CORRUPTION_DETECTED
PSA_ERROR_STORAGE_FAILURE	The key could not be retrieved from storage.
PSA_ERROR_BAD_STATE	The library has not been previously initialized by psa_crypto_init(). It is implementation-dependent whether a failure to initialize results in this error code.

Note

To verify the MAC of a message against an expected value, use psa_mac_verify() instead. Beware that comparing integrity or authenticity data such as MAC values with a function such as memcmp is risky because the time taken by the comparison may leak information about the MAC value which could allow an attacker to guess a valid MAC and thereby bypass security controls.

Parameters

	handle	Handle to the key to use for the operation.
	alg	The MAC algorithm to compute (PSA_ALG_XXX value such that PSA_ALG_IS_MAC(alg) is true).
[in]	input	Buffer containing the input message.
	input_length	Size of the input buffer in bytes.
[out]	mac	Buffer where the MAC value is to be written.
	mac_size	Size of the mac buffer in bytes.
[out]	mac_length	On success, the number of bytes that make up the MAC value.

Return values

PSA_SUCCESS	Success.
PSA_ERROR_INVALID_HANDLE
PSA_ERROR_NOT_PERMITTED
PSA_ERROR_INVALID_ARGUMENT	handle is not compatible with alg.
PSA_ERROR_NOT_SUPPORTED	alg is not supported or is not a MAC algorithm.
PSA_ERROR_BUFFER_TOO_SMALL	mac_size is too small
PSA_ERROR_INSUFFICIENT_MEMORY
PSA_ERROR_COMMUNICATION_FAILURE
PSA_ERROR_HARDWARE_FAILURE
PSA_ERROR_CORRUPTION_DETECTED
PSA_ERROR_STORAGE_FAILURE	The key could not be retrieved from storage.
PSA_ERROR_BAD_STATE	The library has not been previously initialized by psa_crypto_init(). It is implementation-dependent whether a failure to initialize results in this error code.

Return an initial value for a MAC operation object.

Finish the calculation of the MAC of a message.

The application must call psa_mac_sign_setup() before calling this function. This function calculates the MAC of the message formed by concatenating the inputs passed to preceding calls to psa_mac_update().

When this function returns successfuly, the operation becomes inactive. If this function returns an error status, the operation enters an error state and must be aborted by calling psa_mac_abort().

Warning

Applications should not call this function if they expect a specific value for the MAC. Call psa_mac_verify_finish() instead. Beware that comparing integrity or authenticity data such as MAC values with a function such as memcmp is risky because the time taken by the comparison may leak information about the MAC value which could allow an attacker to guess a valid MAC and thereby bypass security controls.

Parameters

[in,out]	operation	Active MAC operation.
[out]	mac	Buffer where the MAC value is to be written.
	mac_size	Size of the mac buffer in bytes.
[out]	mac_length	On success, the number of bytes that make up the MAC value. This is always #PSA_MAC_FINAL_SIZE(key_type, key_bits, alg) where key_type and key_bits are the type and bit-size respectively of the key and alg is the MAC algorithm that is calculated.

Return values

PSA_SUCCESS	Success.
PSA_ERROR_BAD_STATE	The operation state is not valid (it must be an active mac sign operation).
PSA_ERROR_BUFFER_TOO_SMALL	The size of the mac buffer is too small. You can determine a sufficient buffer size by calling PSA_MAC_FINAL_SIZE().
PSA_ERROR_INSUFFICIENT_MEMORY
PSA_ERROR_COMMUNICATION_FAILURE
PSA_ERROR_HARDWARE_FAILURE
PSA_ERROR_CORRUPTION_DETECTED
PSA_ERROR_STORAGE_FAILURE
PSA_ERROR_BAD_STATE	The library has not been previously initialized by psa_crypto_init(). It is implementation-dependent whether a failure to initialize results in this error code.

The application must call psa_mac_sign_setup() before calling this function. This function calculates the MAC of the message formed by concatenating the inputs passed to preceding calls to psa_mac_update().

When this function returns successfuly, the operation becomes inactive. If this function returns an error status, the operation enters an error state and must be aborted by calling psa_mac_abort().

Warning

Applications should not call this function if they expect a specific value for the MAC. Call psa_mac_verify_finish() instead. Beware that comparing integrity or authenticity data such as MAC values with a function such as memcmp is risky because the time taken by the comparison may leak information about the MAC value which could allow an attacker to guess a valid MAC and thereby bypass security controls.

Parameters

[in,out]	operation	Active MAC operation.
[out]	mac	Buffer where the MAC value is to be written.
	mac_size	Size of the mac buffer in bytes.
[out]	mac_length	On success, the number of bytes that make up the MAC value. This is always #PSA_MAC_LENGTH(key_type, key_bits, alg) where key_type and key_bits are the type and bit-size respectively of the key and alg is the MAC algorithm that is calculated.

Return values

PSA_SUCCESS	Success.
PSA_ERROR_BAD_STATE	The operation state is not valid (it must be an active mac sign operation).
PSA_ERROR_BUFFER_TOO_SMALL	The size of the mac buffer is too small. You can determine a sufficient buffer size by calling PSA_MAC_LENGTH().
PSA_ERROR_INSUFFICIENT_MEMORY
PSA_ERROR_COMMUNICATION_FAILURE
PSA_ERROR_HARDWARE_FAILURE
PSA_ERROR_CORRUPTION_DETECTED
PSA_ERROR_STORAGE_FAILURE
PSA_ERROR_BAD_STATE	The library has not been previously initialized by psa_crypto_init(). It is implementation-dependent whether a failure to initialize results in this error code.

Set up a multipart MAC calculation operation.

This function sets up the calculation of the MAC (message authentication code) of a byte string. To verify the MAC of a message against an expected value, use psa_mac_verify_setup() instead.

The sequence of operations to calculate a MAC is as follows:

1. Allocate an operation object which will be passed to all the functions listed here.
2. Initialize the operation object with one of the methods described in the documentation for psa_mac_operation_t, e.g. #PSA_MAC_OPERATION_INIT.
3. Call psa_mac_sign_setup() to specify the algorithm and key.
4. Call psa_mac_update() zero, one or more times, passing a fragment of the message each time. The MAC that is calculated is the MAC of the concatenation of these messages in order.
5. At the end of the message, call psa_mac_sign_finish() to finish calculating the MAC value and retrieve it.

If an error occurs at any step after a call to psa_mac_sign_setup(), the operation will need to be reset by a call to psa_mac_abort(). The application may call psa_mac_abort() at any time after the operation has been initialized.

After a successful call to psa_mac_sign_setup(), the application must eventually terminate the operation through one of the following methods:

• A successful call to psa_mac_sign_finish().
• A call to psa_mac_abort().

Parameters

[in,out]	operation	The operation object to set up. It must have been initialized as per the documentation for psa_mac_operation_t and not yet in use.
	key	Identifier of the key to use for the operation. It must remain valid until the operation terminates. It must allow the usage PSA_KEY_USAGE_SIGN_MESSAGE.
	alg	The MAC algorithm to compute (PSA_ALG_XXX value such that PSA_ALG_IS_MAC(alg) is true).

Return values

PSA_SUCCESS	Success.
PSA_ERROR_INVALID_HANDLE
PSA_ERROR_NOT_PERMITTED
PSA_ERROR_INVALID_ARGUMENT	key is not compatible with alg.
PSA_ERROR_NOT_SUPPORTED	alg is not supported or is not a MAC algorithm.
PSA_ERROR_INSUFFICIENT_MEMORY
PSA_ERROR_COMMUNICATION_FAILURE
PSA_ERROR_HARDWARE_FAILURE
PSA_ERROR_CORRUPTION_DETECTED
PSA_ERROR_STORAGE_FAILURE	The key could not be retrieved from storage.
PSA_ERROR_BAD_STATE	The operation state is not valid (it must be inactive).
PSA_ERROR_BAD_STATE	The library has not been previously initialized by psa_crypto_init(). It is implementation-dependent whether a failure to initialize results in this error code.

This function sets up the calculation of the MAC (message authentication code) of a byte string. To verify the MAC of a message against an expected value, use psa_mac_verify_setup() instead.

The sequence of operations to calculate a MAC is as follows:

1. Allocate an operation object which will be passed to all the functions listed here.
2. Initialize the operation object with one of the methods described in the documentation for psa_mac_operation_t, e.g. #PSA_MAC_OPERATION_INIT.
3. Call psa_mac_sign_setup() to specify the algorithm and key.
4. Call psa_mac_update() zero, one or more times, passing a fragment of the message each time. The MAC that is calculated is the MAC of the concatenation of these messages in order.
5. At the end of the message, call psa_mac_sign_finish() to finish calculating the MAC value and retrieve it.

If an error occurs at any step after a call to psa_mac_sign_setup(), the operation will need to be reset by a call to psa_mac_abort(). The application may call psa_mac_abort() at any time after the operation has been initialized.

After a successful call to psa_mac_sign_setup(), the application must eventually terminate the operation through one of the following methods:

• A successful call to psa_mac_sign_finish().
• A call to psa_mac_abort().

Parameters

[in,out]	operation	The operation object to set up. It must have been initialized as per the documentation for psa_mac_operation_t and not yet in use.
	handle	Handle to the key to use for the operation. It must remain valid until the operation terminates.
	alg	The MAC algorithm to compute (PSA_ALG_XXX value such that PSA_ALG_IS_MAC(alg) is true).

Return values

PSA_SUCCESS	Success.
PSA_ERROR_INVALID_HANDLE
PSA_ERROR_NOT_PERMITTED
PSA_ERROR_INVALID_ARGUMENT	handle is not compatible with alg.
PSA_ERROR_NOT_SUPPORTED	alg is not supported or is not a MAC algorithm.
PSA_ERROR_INSUFFICIENT_MEMORY
PSA_ERROR_COMMUNICATION_FAILURE
PSA_ERROR_HARDWARE_FAILURE
PSA_ERROR_CORRUPTION_DETECTED
PSA_ERROR_STORAGE_FAILURE	The key could not be retrieved from storage.
PSA_ERROR_BAD_STATE	The operation state is not valid (it must be inactive).
PSA_ERROR_BAD_STATE	The library has not been previously initialized by psa_crypto_init(). It is implementation-dependent whether a failure to initialize results in this error code.

Add a message fragment to a multipart MAC operation.

The application must call psa_mac_sign_setup() or psa_mac_verify_setup() before calling this function.

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

Parameters

[in,out]	operation	Active MAC operation.
[in]	input	Buffer containing the message fragment to add to the MAC calculation.
	input_length	Size of the input buffer in bytes.

Return values

PSA_SUCCESS	Success.
PSA_ERROR_BAD_STATE	The operation state is not valid (it must be active).
PSA_ERROR_INSUFFICIENT_MEMORY
PSA_ERROR_COMMUNICATION_FAILURE
PSA_ERROR_HARDWARE_FAILURE
PSA_ERROR_CORRUPTION_DETECTED
PSA_ERROR_STORAGE_FAILURE
PSA_ERROR_BAD_STATE	The library has not been previously initialized by psa_crypto_init(). It is implementation-dependent whether a failure to initialize results in this error code.

Calculate the MAC of a message and compare it with a reference value.

Parameters

	key	Identifier of the key to use for the operation. It must allow the usage PSA_KEY_USAGE_VERIFY_MESSAGE.
	alg	The MAC algorithm to compute (PSA_ALG_XXX value such that PSA_ALG_IS_MAC(alg) is true).
[in]	input	Buffer containing the input message.
	input_length	Size of the input buffer in bytes.
[out]	mac	Buffer containing the expected MAC value.
	mac_length	Size of the mac buffer in bytes.

Return values

PSA_SUCCESS	The expected MAC is identical to the actual MAC of the input.
PSA_ERROR_INVALID_SIGNATURE	The MAC of the message was calculated successfully, but it differs from the expected value.
PSA_ERROR_INVALID_HANDLE
PSA_ERROR_NOT_PERMITTED
PSA_ERROR_INVALID_ARGUMENT	key is not compatible with alg.
PSA_ERROR_NOT_SUPPORTED	alg is not supported or is not a MAC algorithm.
PSA_ERROR_INSUFFICIENT_MEMORY
PSA_ERROR_COMMUNICATION_FAILURE
PSA_ERROR_HARDWARE_FAILURE
PSA_ERROR_CORRUPTION_DETECTED
PSA_ERROR_STORAGE_FAILURE	The key could not be retrieved from storage.
PSA_ERROR_BAD_STATE	The library has not been previously initialized by psa_crypto_init(). It is implementation-dependent whether a failure to initialize results in this error code.

Parameters

	handle	Handle to the key to use for the operation.
	alg	The MAC algorithm to compute (PSA_ALG_XXX value such that PSA_ALG_IS_MAC(alg) is true).
[in]	input	Buffer containing the input message.
	input_length	Size of the input buffer in bytes.
[out]	mac	Buffer containing the expected MAC value.
	mac_length	Size of the mac buffer in bytes.

Return values

PSA_SUCCESS	The expected MAC is identical to the actual MAC of the input.
PSA_ERROR_INVALID_SIGNATURE	The MAC of the message was calculated successfully, but it differs from the expected value.
PSA_ERROR_INVALID_HANDLE
PSA_ERROR_NOT_PERMITTED
PSA_ERROR_INVALID_ARGUMENT	handle is not compatible with alg.
PSA_ERROR_NOT_SUPPORTED	alg is not supported or is not a MAC algorithm.
PSA_ERROR_INSUFFICIENT_MEMORY
PSA_ERROR_COMMUNICATION_FAILURE
PSA_ERROR_HARDWARE_FAILURE
PSA_ERROR_CORRUPTION_DETECTED
PSA_ERROR_STORAGE_FAILURE	The key could not be retrieved from storage.
PSA_ERROR_BAD_STATE	The library has not been previously initialized by psa_crypto_init(). It is implementation-dependent whether a failure to initialize results in this error code.

Finish the calculation of the MAC of a message and compare it with an expected value.

The application must call psa_mac_verify_setup() before calling this function. This function calculates the MAC of the message formed by concatenating the inputs passed to preceding calls to psa_mac_update(). It then compares the calculated MAC with the expected MAC passed as a parameter to this function.

When this function returns successfuly, the operation becomes inactive. If this function returns an error status, the operation enters an error state and must be aborted by calling psa_mac_abort().

Note

Implementations shall make the best effort to ensure that the comparison between the actual MAC and the expected MAC is performed in constant time.

Parameters

[in,out]	operation	Active MAC operation.
[in]	mac	Buffer containing the expected MAC value.
	mac_length	Size of the mac buffer in bytes.

Return values

PSA_SUCCESS	The expected MAC is identical to the actual MAC of the message.
PSA_ERROR_INVALID_SIGNATURE	The MAC of the message was calculated successfully, but it differs from the expected MAC.
PSA_ERROR_BAD_STATE	The operation state is not valid (it must be an active mac verify operation).
PSA_ERROR_INSUFFICIENT_MEMORY
PSA_ERROR_COMMUNICATION_FAILURE
PSA_ERROR_HARDWARE_FAILURE
PSA_ERROR_CORRUPTION_DETECTED
PSA_ERROR_STORAGE_FAILURE
PSA_ERROR_BAD_STATE	The library has not been previously initialized by psa_crypto_init(). It is implementation-dependent whether a failure to initialize results in this error code.

Set up a multipart MAC verification operation.

This function sets up the verification of the MAC (message authentication code) of a byte string against an expected value.

The sequence of operations to verify a MAC is as follows:

1. Allocate an operation object which will be passed to all the functions listed here.
2. Initialize the operation object with one of the methods described in the documentation for psa_mac_operation_t, e.g. #PSA_MAC_OPERATION_INIT.
3. Call psa_mac_verify_setup() to specify the algorithm and key.
4. Call psa_mac_update() zero, one or more times, passing a fragment of the message each time. The MAC that is calculated is the MAC of the concatenation of these messages in order.
5. At the end of the message, call psa_mac_verify_finish() to finish calculating the actual MAC of the message and verify it against the expected value.

If an error occurs at any step after a call to psa_mac_verify_setup(), the operation will need to be reset by a call to psa_mac_abort(). The application may call psa_mac_abort() at any time after the operation has been initialized.

After a successful call to psa_mac_verify_setup(), the application must eventually terminate the operation through one of the following methods:

• A successful call to psa_mac_verify_finish().
• A call to psa_mac_abort().

Parameters

[in,out]	operation	The operation object to set up. It must have been initialized as per the documentation for psa_mac_operation_t and not yet in use.
	key	Identifier of the key to use for the operation. It must remain valid until the operation terminates. It must allow the usage PSA_KEY_USAGE_VERIFY_MESSAGE.
	alg	The MAC algorithm to compute (PSA_ALG_XXX value such that PSA_ALG_IS_MAC(alg) is true).

Return values

PSA_SUCCESS	Success.
PSA_ERROR_INVALID_HANDLE
PSA_ERROR_NOT_PERMITTED
PSA_ERROR_INVALID_ARGUMENT	key is not compatible with alg.
PSA_ERROR_NOT_SUPPORTED	alg is not supported or is not a MAC algorithm.
PSA_ERROR_INSUFFICIENT_MEMORY
PSA_ERROR_COMMUNICATION_FAILURE
PSA_ERROR_HARDWARE_FAILURE
PSA_ERROR_CORRUPTION_DETECTED
PSA_ERROR_STORAGE_FAILURE	The key could not be retrieved from storage
PSA_ERROR_BAD_STATE	The operation state is not valid (it must be inactive).
PSA_ERROR_BAD_STATE	The library has not been previously initialized by psa_crypto_init(). It is implementation-dependent whether a failure to initialize results in this error code.

This function sets up the verification of the MAC (message authentication code) of a byte string against an expected value.

The sequence of operations to verify a MAC is as follows:

1. Allocate an operation object which will be passed to all the functions listed here.
2. Initialize the operation object with one of the methods described in the documentation for psa_mac_operation_t, e.g. #PSA_MAC_OPERATION_INIT.
3. Call psa_mac_verify_setup() to specify the algorithm and key.
4. Call psa_mac_update() zero, one or more times, passing a fragment of the message each time. The MAC that is calculated is the MAC of the concatenation of these messages in order.
5. At the end of the message, call psa_mac_verify_finish() to finish calculating the actual MAC of the message and verify it against the expected value.

If an error occurs at any step after a call to psa_mac_verify_setup(), the operation will need to be reset by a call to psa_mac_abort(). The application may call psa_mac_abort() at any time after the operation has been initialized.

After a successful call to psa_mac_verify_setup(), the application must eventually terminate the operation through one of the following methods:

• A successful call to psa_mac_verify_finish().
• A call to psa_mac_abort().

Parameters

[in,out]	operation	The operation object to set up. It must have been initialized as per the documentation for psa_mac_operation_t and not yet in use.
	handle	Handle to the key to use for the operation. It must remain valid until the operation terminates.
	alg	The MAC algorithm to compute (PSA_ALG_XXX value such that PSA_ALG_IS_MAC(alg) is true).

Return values

PSA_SUCCESS	Success.
PSA_ERROR_INVALID_HANDLE
PSA_ERROR_NOT_PERMITTED
PSA_ERROR_INVALID_ARGUMENT	key is not compatible with alg.
PSA_ERROR_NOT_SUPPORTED	alg is not supported or is not a MAC algorithm.
PSA_ERROR_INSUFFICIENT_MEMORY
PSA_ERROR_COMMUNICATION_FAILURE
PSA_ERROR_HARDWARE_FAILURE
PSA_ERROR_CORRUPTION_DETECTED
PSA_ERROR_STORAGE_FAILURE	The key could not be retrieved from storage
PSA_ERROR_BAD_STATE	The operation state is not valid (it must be inactive).
PSA_ERROR_BAD_STATE	The library has not been previously initialized by psa_crypto_init(). It is implementation-dependent whether a failure to initialize results in this error code.