hash

# Message digests

struct psa_hash_operation_s typedef struct psa_hash_operation_s psa_hash_operation_t psa_hash_operation_t

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

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

- Set the structure to all-bits-zero, for example:

      psa_hash_operation_toperation;
      memset(&operation,0,sizeof(operation));

- Initialize the structure to logical zero values, for example:

      psa_hash_operation_toperation={0};

- Initialize the structure to the initializer PSA_HASH_OPERATION_INIT, for example:

      psa_hash_operation_toperation=PSA_HASH_OPERATION_INIT;

- Assign the result of the function psa_hash_operation_init() to the structure, for example:

      psa_hash_operation_toperation;
      operation=psa_hash_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.

psa_status_t psa_status_t psa_hash_compute (psa_algorithm_t alg, const uint8_t *input, size_t input_length, uint8_t *hash, size_t hash_size, size_t *hash_length) psa_hash_compute psa_algorithm_t alg const uint8_t * input size_t input_length uint8_t * hash size_t hash_size size_t * hash_length

Calculate the hash (digest) of a message.

To verify the hash of a message against an expected value, use psa_hash_compare() instead.

alg

The hash algorithm to compute (`PSA_ALG_XXX` value such that PSA_ALG_IS_HASH(`alg`) is true).

input

Buffer containing the message to hash.

input_length

Size of the `input` buffer in bytes.

hash

Buffer where the hash is to be written.

hash_size

Size of the `hash` buffer in bytes.

hash_length

On success, the number of bytes that make up the hash value. This is always PSA_HASH_LENGTH(`alg`).

PSA_SUCCESS

Success.

PSA_ERROR_NOT_SUPPORTED

`alg` is not supported or is not a hash algorithm.

PSA_ERROR_INVALID_ARGUMENT

PSA_ERROR_BUFFER_TOO_SMALL

`hash_size` is too small

PSA_ERROR_INSUFFICIENT_MEMORY

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.

psa_status_t psa_status_t psa_hash_compare (psa_algorithm_t alg, const uint8_t *input, size_t input_length, const uint8_t *hash, size_t hash_length) psa_hash_compare psa_algorithm_t alg const uint8_t * input size_t input_length const uint8_t * hash size_t hash_length

Calculate the hash (digest) of a message and compare it with a reference value.

alg

The hash algorithm to compute (`PSA_ALG_XXX` value such that PSA_ALG_IS_HASH(`alg`) is true).

input

Buffer containing the message to hash.

input_length

Size of the `input` buffer in bytes.

hash

Buffer containing the expected hash value.

hash_length

Size of the `hash` buffer in bytes.

PSA_SUCCESS

The expected hash is identical to the actual hash of the input.

PSA_ERROR_INVALID_SIGNATURE

The hash of the message was calculated successfully, but it differs from the expected hash.

PSA_ERROR_NOT_SUPPORTED

`alg` is not supported or is not a hash algorithm.

PSA_ERROR_INVALID_ARGUMENT

`input_length` or `hash_length` do not match the hash size for `alg`

PSA_ERROR_INSUFFICIENT_MEMORY

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.

psa_hash_operation_t static psa_hash_operation_t psa_hash_operation_init (void) psa_hash_operation_init void

Return an initial value for a hash operation object.

psa_status_t psa_status_t psa_hash_setup (psa_hash_operation_t *operation, psa_algorithm_t alg) psa_hash_setup psa_hash_operation_t * operation psa_algorithm_t alg

Set up a multipart hash operation.

The sequence of operations to calculate a hash (message digest) 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_hash_operation_t, e.g. PSA_HASH_OPERATION_INIT.

3. Call psa_hash_setup() to specify the algorithm.

4. Call psa_hash_update() zero, one or more times, passing a fragment of the message each time. The hash that is calculated is the hash of the concatenation of these messages in order.

5. To calculate the hash, call psa_hash_finish(). To compare the hash with an expected value, call psa_hash_verify().

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

After a successful call to psa_hash_setup(), the application must eventually terminate the operation. The following events terminate an operation:

- A successful call to psa_hash_finish() or psa_hash_verify().

- A call to psa_hash_abort().

operation

The operation object to set up. It must have been initialized as per the documentation for psa_hash_operation_t and not yet in use.

alg

The hash algorithm to compute (`PSA_ALG_XXX` value such that PSA_ALG_IS_HASH(`alg`) is true).

PSA_SUCCESS

Success.

PSA_ERROR_NOT_SUPPORTED

`alg` is not a supported hash algorithm.

PSA_ERROR_INVALID_ARGUMENT

`alg` is not a hash algorithm.

PSA_ERROR_INSUFFICIENT_MEMORY

PSA_ERROR_COMMUNICATION_FAILURE

PSA_ERROR_HARDWARE_FAILURE

PSA_ERROR_CORRUPTION_DETECTED

PSA_ERROR_BAD_STATE

The operation state is not valid (it must be inactive), or 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.

psa_status_t psa_status_t psa_hash_update (psa_hash_operation_t *operation, const uint8_t *input, size_t input_length) psa_hash_update psa_hash_operation_t * operation const uint8_t * input size_t input_length

Add a message fragment to a multipart hash operation.

The application must call psa_hash_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_hash_abort().

operation

Active hash operation.

input

Buffer containing the message fragment to hash.

input_length

Size of the `input` buffer in bytes.

PSA_SUCCESS

Success.

PSA_ERROR_INSUFFICIENT_MEMORY

PSA_ERROR_COMMUNICATION_FAILURE

PSA_ERROR_HARDWARE_FAILURE

PSA_ERROR_CORRUPTION_DETECTED

PSA_ERROR_BAD_STATE

The operation state is not valid (it must be active), or 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.

psa_status_t psa_status_t psa_hash_finish (psa_hash_operation_t *operation, uint8_t *hash, size_t hash_size, size_t *hash_length) psa_hash_finish psa_hash_operation_t * operation uint8_t * hash size_t hash_size size_t * hash_length

Finish the calculation of the hash of a message.

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

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

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

operation

Active hash operation.

hash

Buffer where the hash is to be written.

hash_size

Size of the `hash` buffer in bytes.

hash_length

On success, the number of bytes that make up the hash value. This is always PSA_HASH_LENGTH(`alg`) where `alg` is the hash algorithm that is calculated.

PSA_SUCCESS

Success.

PSA_ERROR_BUFFER_TOO_SMALL

The size of the `hash` buffer is too small. You can determine a sufficient buffer size by calling PSA_HASH_LENGTH(`alg`) where `alg` is the hash algorithm that is calculated.

PSA_ERROR_INSUFFICIENT_MEMORY

PSA_ERROR_COMMUNICATION_FAILURE

PSA_ERROR_HARDWARE_FAILURE

PSA_ERROR_CORRUPTION_DETECTED

PSA_ERROR_BAD_STATE

The operation state is not valid (it must be active), or 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.

psa_status_t psa_status_t psa_hash_verify (psa_hash_operation_t *operation, const uint8_t *hash, size_t hash_length) psa_hash_verify psa_hash_operation_t * operation const uint8_t * hash size_t hash_length

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

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

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

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

operation

Active hash operation.

hash

Buffer containing the expected hash value.

hash_length

Size of the `hash` buffer in bytes.

PSA_SUCCESS

The expected hash is identical to the actual hash of the message.

PSA_ERROR_INVALID_SIGNATURE

The hash of the message was calculated successfully, but it differs from the expected hash.

PSA_ERROR_INSUFFICIENT_MEMORY

PSA_ERROR_COMMUNICATION_FAILURE

PSA_ERROR_HARDWARE_FAILURE

PSA_ERROR_CORRUPTION_DETECTED

PSA_ERROR_BAD_STATE

The operation state is not valid (it must be active), or 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.

psa_status_t psa_status_t psa_hash_abort (psa_hash_operation_t *operation) psa_hash_abort psa_hash_operation_t * operation

Abort a hash 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_hash_setup() again.

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

In particular, calling psa_hash_abort() after the operation has been terminated by a call to psa_hash_abort(), psa_hash_finish() or psa_hash_verify() is safe and has no effect.

operation

Initialized hash operation.

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.

psa_status_t psa_status_t psa_hash_clone (const psa_hash_operation_t *source_operation, psa_hash_operation_t *target_operation) psa_hash_clone const psa_hash_operation_t * source_operation psa_hash_operation_t * target_operation

Clone a hash operation.

This function copies the state of an ongoing hash operation to a new operation object. In other words, this function is equivalent to calling psa_hash_setup() on `target_operation` with the same algorithm that `source_operation` was set up for, then psa_hash_update() on `target_operation` with the same input that that was passed to `source_operation`. After this function returns, the two objects are independent, i.e. subsequent calls involving one of the objects do not affect the other object.

source_operation

The active hash operation to clone.

target_operation

The operation object to set up. It must be initialized but not active.

PSA_SUCCESS

PSA_ERROR_COMMUNICATION_FAILURE

PSA_ERROR_HARDWARE_FAILURE

PSA_ERROR_CORRUPTION_DETECTED

PSA_ERROR_INSUFFICIENT_MEMORY

PSA_ERROR_BAD_STATE

The `source_operation` state is not valid (it must be active), or the `target_operation` state is not valid (it must be inactive), or 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.

PSA_HASH_OPERATION_INIT
{ 0, { 0 } }

This macro returns a suitable initializer for a hash operation object of type psa_hash_operation_t.