cipher

# Symmetric ciphers

struct psa_cipher_operation_s typedef struct psa_cipher_operation_s psa_cipher_operation_t psa_cipher_operation_t

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

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

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

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

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

      psa_cipher_operation_toperation={0};

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

      psa_cipher_operation_toperation=PSA_CIPHER_OPERATION_INIT;

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

      psa_cipher_operation_toperation;
      operation=psa_cipher_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_cipher_encrypt (mbedtls_svc_key_id_t key, psa_algorithm_t alg, const uint8_t *input, size_t input_length, uint8_t *output, size_t output_size, size_t *output_length) psa_cipher_encrypt mbedtls_svc_key_id_t key psa_algorithm_t alg const uint8_t * input size_t input_length uint8_t * output size_t output_size size_t * output_length

Encrypt a message using a symmetric cipher.

This function encrypts a message with a random IV (initialization vector). Use the multipart operation interface with a psa_cipher_operation_t object to provide other forms of IV.

key

Identifier of the key to use for the operation. It must allow the usage PSA_KEY_USAGE_ENCRYPT.

alg

The cipher algorithm to compute (`PSA_ALG_XXX` value such that PSA_ALG_IS_CIPHER(`alg`) is true).

input

Buffer containing the message to encrypt.

input_length

Size of the `input` buffer in bytes.

output

Buffer where the output is to be written. The output contains the IV followed by the ciphertext proper.

output_size

Size of the `output` buffer in bytes.

output_length

On success, the number of bytes that make up the output.

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 cipher algorithm.

PSA_ERROR_BUFFER_TOO_SMALL

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.

psa_status_t psa_status_t psa_cipher_decrypt (mbedtls_svc_key_id_t key, psa_algorithm_t alg, const uint8_t *input, size_t input_length, uint8_t *output, size_t output_size, size_t *output_length) psa_cipher_decrypt mbedtls_svc_key_id_t key psa_algorithm_t alg const uint8_t * input size_t input_length uint8_t * output size_t output_size size_t * output_length

Decrypt a message using a symmetric cipher.

This function decrypts a message encrypted with a symmetric cipher.

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_DECRYPT.

alg

The cipher algorithm to compute (`PSA_ALG_XXX` value such that PSA_ALG_IS_CIPHER(`alg`) is true).

input

Buffer containing the message to decrypt. This consists of the IV followed by the ciphertext proper.

input_length

Size of the `input` buffer in bytes.

output

Buffer where the plaintext is to be written.

output_size

Size of the `output` buffer in bytes.

output_length

On success, the number of bytes that make up the output.

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 cipher algorithm.

PSA_ERROR_BUFFER_TOO_SMALL

PSA_ERROR_INSUFFICIENT_MEMORY

PSA_ERROR_COMMUNICATION_FAILURE

PSA_ERROR_HARDWARE_FAILURE

PSA_ERROR_STORAGE_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_cipher_operation_t static psa_cipher_operation_t psa_cipher_operation_init (void) psa_cipher_operation_init void

Return an initial value for a cipher operation object.

psa_status_t psa_status_t psa_cipher_encrypt_setup (psa_cipher_operation_t *operation, mbedtls_svc_key_id_t key, psa_algorithm_t alg) psa_cipher_encrypt_setup psa_cipher_operation_t * operation mbedtls_svc_key_id_t key psa_algorithm_t alg

Set the key for a multipart symmetric encryption operation.

The sequence of operations to encrypt a message with a symmetric cipher 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_cipher_operation_t, e.g. PSA_CIPHER_OPERATION_INIT.

3. Call psa_cipher_encrypt_setup() to specify the algorithm and key.

4. Call either psa_cipher_generate_iv() or psa_cipher_set_iv() to generate or set the IV (initialization vector). You should use psa_cipher_generate_iv() unless the protocol you are implementing requires a specific IV value.

5. Call psa_cipher_update() zero, one or more times, passing a fragment of the message each time.

6. Call psa_cipher_finish().

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

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

- A successful call to psa_cipher_finish().

- A call to psa_cipher_abort().

operation

The operation object to set up. It must have been initialized as per the documentation for psa_cipher_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_ENCRYPT.

alg

The cipher algorithm to compute (`PSA_ALG_XXX` value such that PSA_ALG_IS_CIPHER(`alg`) is true).

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 cipher algorithm.

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 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_cipher_decrypt_setup (psa_cipher_operation_t *operation, mbedtls_svc_key_id_t key, psa_algorithm_t alg) psa_cipher_decrypt_setup psa_cipher_operation_t * operation mbedtls_svc_key_id_t key psa_algorithm_t alg

Set the key for a multipart symmetric decryption operation.

The sequence of operations to decrypt a message with a symmetric cipher 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_cipher_operation_t, e.g. PSA_CIPHER_OPERATION_INIT.

3. Call psa_cipher_decrypt_setup() to specify the algorithm and key.

4. Call psa_cipher_set_iv() with the IV (initialization vector) for the decryption. If the IV is prepended to the ciphertext, you can call psa_cipher_update() on a buffer containing the IV followed by the beginning of the message.

5. Call psa_cipher_update() zero, one or more times, passing a fragment of the message each time.

6. Call psa_cipher_finish().

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

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

- A successful call to psa_cipher_finish().

- A call to psa_cipher_abort().

operation

The operation object to set up. It must have been initialized as per the documentation for psa_cipher_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_DECRYPT.

alg

The cipher algorithm to compute (`PSA_ALG_XXX` value such that PSA_ALG_IS_CIPHER(`alg`) is true).

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 cipher algorithm.

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 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_cipher_generate_iv (psa_cipher_operation_t *operation, uint8_t *iv, size_t iv_size, size_t *iv_length) psa_cipher_generate_iv psa_cipher_operation_t * operation uint8_t * iv size_t iv_size size_t * iv_length

Generate an IV for a symmetric encryption operation.

This function generates a random IV (initialization vector), nonce or initial counter value for the encryption operation as appropriate for the chosen algorithm, key type and key size.

The application must call psa_cipher_encrypt_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_cipher_abort().

operation

Active cipher operation.

iv

Buffer where the generated IV is to be written.

iv_size

Size of the `iv` buffer in bytes.

iv_length

On success, the number of bytes of the generated IV.

PSA_SUCCESS

Success.

PSA_ERROR_BUFFER_TOO_SMALL

The size of the `iv` buffer is too small.

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 operation state is not valid (it must be active, with no IV set), 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_cipher_set_iv (psa_cipher_operation_t *operation, const uint8_t *iv, size_t iv_length) psa_cipher_set_iv psa_cipher_operation_t * operation const uint8_t * iv size_t iv_length

Set the IV for a symmetric encryption or decryption operation.

This function sets the IV (initialization vector), nonce or initial counter value for the encryption or decryption operation.

The application must call psa_cipher_encrypt_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_cipher_abort().

When encrypting, applications should use psa_cipher_generate_iv() instead of this function, unless implementing a protocol that requires a non-random IV.

operation

Active cipher operation.

iv

Buffer containing the IV to use.

iv_length

Size of the IV in bytes.

PSA_SUCCESS

Success.

PSA_ERROR_INVALID_ARGUMENT

The size of `iv` is not acceptable for the chosen algorithm, or the chosen algorithm does not use an IV.

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 operation state is not valid (it must be an active cipher encrypt operation, with no IV set), 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_cipher_update (psa_cipher_operation_t *operation, const uint8_t *input, size_t input_length, uint8_t *output, size_t output_size, size_t *output_length) psa_cipher_update psa_cipher_operation_t * operation const uint8_t * input size_t input_length uint8_t * output size_t output_size size_t * output_length

Encrypt or decrypt a message fragment in an active cipher operation.

Before calling this function, you must:

1. Call either psa_cipher_encrypt_setup() or psa_cipher_decrypt_setup(). The choice of setup function determines whether this function encrypts or decrypts its input.

2. If the algorithm requires an IV, call psa_cipher_generate_iv() (recommended when encrypting) or psa_cipher_set_iv().

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

operation

Active cipher operation.

input

Buffer containing the message fragment to encrypt or decrypt.

input_length

Size of the `input` buffer in bytes.

output

Buffer where the output is to be written.

output_size

Size of the `output` buffer in bytes.

output_length

On success, the number of bytes that make up the returned output.

PSA_SUCCESS

Success.

PSA_ERROR_BUFFER_TOO_SMALL

The size of the `output` buffer is too small.

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 operation state is not valid (it must be active, with an IV set if required for the algorithm), 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_cipher_finish (psa_cipher_operation_t *operation, uint8_t *output, size_t output_size, size_t *output_length) psa_cipher_finish psa_cipher_operation_t * operation uint8_t * output size_t output_size size_t * output_length

Finish encrypting or decrypting a message in a cipher operation.

The application must call psa_cipher_encrypt_setup() or psa_cipher_decrypt_setup() before calling this function. The choice of setup function determines whether this function encrypts or decrypts its input.

This function finishes the encryption or decryption of the message formed by concatenating the inputs passed to preceding calls to psa_cipher_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_cipher_abort().

operation

Active cipher operation.

output

Buffer where the output is to be written.

output_size

Size of the `output` buffer in bytes.

output_length

On success, the number of bytes that make up the returned output.

PSA_SUCCESS

Success.

PSA_ERROR_INVALID_ARGUMENT

The total input size passed to this operation is not valid for this particular algorithm. For example, the algorithm is a based on block cipher and requires a whole number of blocks, but the total input size is not a multiple of the block size.

PSA_ERROR_INVALID_PADDING

This is a decryption operation for an algorithm that includes padding, and the ciphertext does not contain valid padding.

PSA_ERROR_BUFFER_TOO_SMALL

The size of the `output` buffer is too small.

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 operation state is not valid (it must be active, with an IV set if required for the algorithm), 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_cipher_abort (psa_cipher_operation_t *operation) psa_cipher_abort psa_cipher_operation_t * operation

Abort a cipher 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_cipher_encrypt_setup() or psa_cipher_decrypt_setup() again.

You may call this function any time after the operation object has been initialized as described in psa_cipher_operation_t.

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

operation

Initialized cipher 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_CIPHER_OPERATION_INIT
{ 0, 0, 0, 0, { 0 } }

This macro returns a suitable initializer for a cipher operation object of type psa_cipher_operation_t.