Message digests

## Macros

#define | PSA_HASH_OPERATION_INIT {0, {0}}

## Typedefs

typedef struct psa_hash_operation_s | psa_hash_operation_t

## Functions

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_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)
static psa_hash_operation_t | psa_hash_operation_init (void)
psa_status_t | psa_hash_setup (psa_hash_operation_t *operation, psa_algorithm_t alg)
psa_status_t | psa_hash_update (psa_hash_operation_t *operation, const uint8_t *input, size_t input_length)
psa_status_t | psa_hash_finish (psa_hash_operation_t *operation, uint8_t *hash, size_t hash_size, size_t *hash_length)
psa_status_t | psa_hash_verify (psa_hash_operation_t *operation, const uint8_t *hash, size_t hash_length)
psa_status_t | psa_hash_abort (psa_hash_operation_t *operation)
psa_status_t | psa_hash_clone (const psa_hash_operation_t *source_operation, psa_hash_operation_t *target_operation)

## Detailed Description

## Macro Definition Documentation

## PSA_HASH_OPERATION_INIT

#define PSA_HASH_OPERATION_INIT {0, {0}}

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

Definition at line 95 of file crypto_struct.h.

## Typedef Documentation

## psa_hash_operation_t

typedef struct psa_hash_operation_s 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_t operation;
  memset(&operation, 0, sizeof(operation));
  psa_hash_operation_s
  Definition: crypto_struct.h:84
- Initialize the structure to logical zero values, for example:
  psa_hash_operation_t operation = {0};
- Initialize the structure to the initializer PSA_HASH_OPERATION_INIT, for example:
  psa_hash_operation_t operation = PSA_HASH_OPERATION_INIT;
  PSA_HASH_OPERATION_INIT
  #define PSA_HASH_OPERATION_INIT
  Definition: crypto_struct.h:95
- Assign the result of the function psa_hash_operation_init() to the structure, for example:
  psa_hash_operation_t operation;
  operation = psa_hash_operation_init();
  psa_hash_operation_init
  static psa_hash_operation_t psa_hash_operation_init(void)

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 909 of file crypto.h.

## Function Documentation

## psa_hash_abort()

psa_status_t 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.

Parameters

  [in,out] | operation | Initialized hash 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.

## psa_hash_clone()

psa_status_t 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.

Parameters

  [in] | source_operation | The active hash operation to clone.
  [in,out] | target_operation | The operation object to set up. It must be initialized but not active.

Return values

  PSA_SUCCESS |
  PSA_ERROR_BAD_STATE | The `source_operation` state is not valid (it must be active).
  PSA_ERROR_BAD_STATE | The `target_operation` state is not valid (it must be inactive).
  PSA_ERROR_COMMUNICATION_FAILURE |
  PSA_ERROR_HARDWARE_FAILURE |
  PSA_ERROR_CORRUPTION_DETECTED |
  PSA_ERROR_INSUFFICIENT_MEMORY |
  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_compare()

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
| ) |  |

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

Parameters

  | alg | The hash algorithm to compute (`PSA_ALG_XXX` value such that PSA_ALG_IS_HASH(`alg`) is true).
  [in] | input | Buffer containing the message to hash.
  | input_length | Size of the `input` buffer in bytes.
  [out] | hash | Buffer containing the expected hash value.
  | hash_length | Size of the `hash` buffer in bytes.

Return values

  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_INSUFFICIENT_MEMORY |
  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_compute()

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
| ) |  |

Calculate the hash (digest) of a message.

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

Parameters

  | alg | The hash algorithm to compute (`PSA_ALG_XXX` value such that PSA_ALG_IS_HASH(`alg`) is true).
  [in] | input | Buffer containing the message to hash.
  | input_length | Size of the `input` buffer in bytes.
  [out] | hash | Buffer where the hash is to be written.
  | hash_size | Size of the `hash` buffer in bytes.
  [out] | hash_length | On success, the number of bytes that make up the hash value. This is always PSA_HASH_LENGTH(`alg`).

Return values

  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_INSUFFICIENT_MEMORY |
  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_finish()

psa_status_t 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 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_hash_abort().

Warning
  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.

Parameters

  [in,out] | operation | Active hash operation.
  [out] | hash | Buffer where the hash is to be written.
  | hash_size | Size of the `hash` buffer in bytes.
  [out] | 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.

Return values

  PSA_SUCCESS | Success.
  PSA_ERROR_BAD_STATE | The operation state is not valid (it must be active).
  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 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()

static psa_hash_operation_t psa_hash_operation_init | ( | void |  | ) |

static

Return an initial value for a hash operation object.

## psa_hash_setup()

psa_status_t 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().

Parameters

  [in,out] | 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).

Return values

  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_BAD_STATE | The operation state is not valid (it must be inactive).
  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_update()

psa_status_t 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().

Parameters

  [in,out] | operation | Active hash operation.
  [in] | input | Buffer containing the message fragment to hash.
  | 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 muct be active).
  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_verify()

psa_status_t 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 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_hash_abort().

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

Parameters

  [in,out] | operation | Active hash operation.
  [in] | hash | Buffer containing the expected hash value.
  | hash_length | Size of the `hash` buffer in bytes.

Return values

  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_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_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.