pake

# Password-authenticated key exchange (PAKE)

uint8_t typedef uint8_t psa_pake_role_t psa_pake_role_t

Encoding of the application role of PAKE.

Encodes the application's role in the algorithm is being executed. For more information see the documentation of individual `PSA_PAKE_ROLE_XXX` constants.

uint8_t typedef uint8_t psa_pake_step_t psa_pake_step_t

Encoding of input and output indicators for PAKE.

Some PAKE algorithms need to exchange more data than just a single key share. This type is for encoding additional input and output data for such algorithms.

uint8_t typedef uint8_t psa_pake_primitive_type_t psa_pake_primitive_type_t

Encoding of the type of the PAKE's primitive.

Values defined by this standard will never be in the range 0x80-0xff. Vendors who define additional types must use an encoding in this range.

For more information see the documentation of individual `PSA_PAKE_PRIMITIVE_TYPE_XXX` constants.

uint8_t typedef uint8_t psa_pake_family_t psa_pake_family_t

Encoding of the family of the primitive associated with the PAKE.

For more information see the documentation of individual `PSA_PAKE_PRIMITIVE_TYPE_XXX` constants.

uint32_t typedef uint32_t psa_pake_primitive_t psa_pake_primitive_t

Encoding of the primitive associated with the PAKE.

For more information see the documentation of the PSA_PAKE_PRIMITIVE macro.

struct psa_pake_cipher_suite_s typedef struct psa_pake_cipher_suite_s psa_pake_cipher_suite_t psa_pake_cipher_suite_t

The type of the data structure for PAKE cipher suites.

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.

struct psa_pake_operation_s typedef struct psa_pake_operation_s psa_pake_operation_t psa_pake_operation_t

The type of the state data structure for PAKE operations.

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

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

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

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

      psa_pake_operation_toperation={0};

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

      psa_pake_operation_toperation=PSA_PAKE_OPERATION_INIT;

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

      psa_pake_operation_toperation;
      operation=psa_pake_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.

struct psa_crypto_driver_pake_inputs_s typedef struct psa_crypto_driver_pake_inputs_s psa_crypto_driver_pake_inputs_t psa_crypto_driver_pake_inputs_t

The type of input values for PAKE operations.

struct psa_jpake_computation_stage_s typedef struct psa_jpake_computation_stage_s psa_jpake_computation_stage_t psa_jpake_computation_stage_t

The type of computation stage for J-PAKE operations.

psa_pake_cipher_suite_t static struct psa_pake_cipher_suite_s psa_pake_cipher_suite_init (void) psa_pake_cipher_suite_init void

Return an initial value for a PAKE cipher suite object.

PSA_PAKE_CIPHER_SUITE_INIT
psa_algorithm_t static psa_algorithm_t psa_pake_cs_get_algorithm (const psa_pake_cipher_suite_t *cipher_suite) psa_pake_cs_get_algorithm const psa_pake_cipher_suite_t * cipher_suite

Retrieve the PAKE algorithm from a PAKE cipher suite.

cipher_suite

The cipher suite structure to query.

The PAKE algorithm stored in the cipher suite structure.

psa_pake_cipher_suite_s::algorithm
void static void psa_pake_cs_set_algorithm (psa_pake_cipher_suite_t *cipher_suite, psa_algorithm_t algorithm) psa_pake_cs_set_algorithm psa_pake_cipher_suite_t * cipher_suite psa_algorithm_t algorithm

Declare the PAKE algorithm for the cipher suite.

This function overwrites any PAKE algorithm previously set in `cipher_suite`.

cipher_suite

The cipher suite structure to write to.

algorithm

The PAKE algorithm to write. (`PSA_ALG_XXX` values of type psa_algorithm_t such that PSA_ALG_IS_PAKE(`alg`) is true.) If this is 0, the PAKE algorithm in `cipher_suite` becomes unspecified.

psa_pake_cipher_suite_s::algorithm
PSA_ALG_IS_PAKE
psa_pake_primitive_t static psa_pake_primitive_t psa_pake_cs_get_primitive (const psa_pake_cipher_suite_t *cipher_suite) psa_pake_cs_get_primitive const psa_pake_cipher_suite_t * cipher_suite

Retrieve the primitive from a PAKE cipher suite.

cipher_suite

The cipher suite structure to query.

The primitive stored in the cipher suite structure.

psa_pake_cipher_suite_s::bits
psa_pake_cipher_suite_s::family
PSA_PAKE_PRIMITIVE
psa_pake_cipher_suite_s::type
void static void psa_pake_cs_set_primitive (psa_pake_cipher_suite_t *cipher_suite, psa_pake_primitive_t primitive) psa_pake_cs_set_primitive psa_pake_cipher_suite_t * cipher_suite psa_pake_primitive_t primitive

Declare the primitive for a PAKE cipher suite.

This function overwrites any primitive previously set in `cipher_suite`.

cipher_suite

The cipher suite structure to write to.

primitive

The primitive to write. If this is 0, the primitive type in `cipher_suite` becomes unspecified.

psa_pake_cipher_suite_s::bits
psa_pake_cipher_suite_s::family
psa_pake_cipher_suite_s::type
psa_pake_family_t static psa_pake_family_t psa_pake_cs_get_family (const psa_pake_cipher_suite_t *cipher_suite) psa_pake_cs_get_family const psa_pake_cipher_suite_t * cipher_suite

Retrieve the PAKE family from a PAKE cipher suite.

cipher_suite

The cipher suite structure to query.

The PAKE family stored in the cipher suite structure.

psa_pake_cipher_suite_s::family
uint16_t static uint16_t psa_pake_cs_get_bits (const psa_pake_cipher_suite_t *cipher_suite) psa_pake_cs_get_bits const psa_pake_cipher_suite_t * cipher_suite

Retrieve the PAKE primitive bit-size from a PAKE cipher suite.

cipher_suite

The cipher suite structure to query.

The PAKE primitive bit-size stored in the cipher suite structure.

psa_pake_cipher_suite_s::bits
psa_algorithm_t static psa_algorithm_t psa_pake_cs_get_hash (const psa_pake_cipher_suite_t *cipher_suite) psa_pake_cs_get_hash const psa_pake_cipher_suite_t * cipher_suite

Retrieve the hash algorithm from a PAKE cipher suite.

cipher_suite

The cipher suite structure to query.

The hash algorithm stored in the cipher suite structure. The return value is 0 if the PAKE is not parametrised by a hash algorithm or if the hash algorithm is not set.

psa_pake_cipher_suite_s::hash
void static void psa_pake_cs_set_hash (psa_pake_cipher_suite_t *cipher_suite, psa_algorithm_t hash) psa_pake_cs_set_hash psa_pake_cipher_suite_t * cipher_suite psa_algorithm_t hash

Declare the hash algorithm for a PAKE cipher suite.

This function overwrites any hash algorithm previously set in `cipher_suite`.

Refer to the documentation of individual PAKE algorithm types (`PSA_ALG_XXX` values of type psa_algorithm_t such that PSA_ALG_IS_PAKE(`alg`) is true) for more information.

cipher_suite

The cipher suite structure to write to.

hash

The hash involved in the cipher suite. (`PSA_ALG_XXX` values of type psa_algorithm_t such that PSA_ALG_IS_HASH(`alg`) is true.) If this is 0, the hash algorithm in `cipher_suite` becomes unspecified.

psa_pake_cipher_suite_s::hash
PSA_ALG_IS_HASH
psa_pake_operation_t static struct psa_pake_operation_s psa_pake_operation_init (void) psa_pake_operation_init void

Return an initial value for a PAKE operation object.

PSA_PAKE_OPERATION_INIT
psa_status_t psa_status_t psa_crypto_driver_pake_get_password_len (const psa_crypto_driver_pake_inputs_t *inputs, size_t *password_len) psa_crypto_driver_pake_get_password_len const psa_crypto_driver_pake_inputs_t * inputs size_t * password_len

Get the length of the password in bytes from given inputs.

inputs

Operation inputs.

password_len

Password length.

PSA_SUCCESS

Success.

PSA_ERROR_BAD_STATE

Password hasn't been set yet.

psa_status_t psa_status_t psa_crypto_driver_pake_get_password (const psa_crypto_driver_pake_inputs_t *inputs, uint8_t *buffer, size_t buffer_size, size_t *buffer_length) psa_crypto_driver_pake_get_password const psa_crypto_driver_pake_inputs_t * inputs uint8_t * buffer size_t buffer_size size_t * buffer_length

Get the password from given inputs.

inputs

Operation inputs.

buffer

Return buffer for password.

buffer_size

Size of the return buffer in bytes.

buffer_length

Actual size of the password in bytes.

PSA_SUCCESS

Success.

PSA_ERROR_BAD_STATE

Password hasn't been set yet.

psa_status_t psa_status_t psa_crypto_driver_pake_get_user_len (const psa_crypto_driver_pake_inputs_t *inputs, size_t *user_len) psa_crypto_driver_pake_get_user_len const psa_crypto_driver_pake_inputs_t * inputs size_t * user_len

Get the length of the user id in bytes from given inputs.

inputs

Operation inputs.

user_len

User id length.

PSA_SUCCESS

Success.

PSA_ERROR_BAD_STATE

User id hasn't been set yet.

psa_status_t psa_status_t psa_crypto_driver_pake_get_peer_len (const psa_crypto_driver_pake_inputs_t *inputs, size_t *peer_len) psa_crypto_driver_pake_get_peer_len const psa_crypto_driver_pake_inputs_t * inputs size_t * peer_len

Get the length of the peer id in bytes from given inputs.

inputs

Operation inputs.

peer_len

Peer id length.

PSA_SUCCESS

Success.

PSA_ERROR_BAD_STATE

Peer id hasn't been set yet.

psa_status_t psa_status_t psa_crypto_driver_pake_get_user (const psa_crypto_driver_pake_inputs_t *inputs, uint8_t *user_id, size_t user_id_size, size_t *user_id_len) psa_crypto_driver_pake_get_user const psa_crypto_driver_pake_inputs_t * inputs uint8_t * user_id size_t user_id_size size_t * user_id_len

Get the user id from given inputs.

inputs

Operation inputs.

user_id

User id.

user_id_size

Size of `user_id` in bytes.

user_id_len

Size of the user id in bytes.

PSA_SUCCESS

Success.

PSA_ERROR_BAD_STATE

User id hasn't been set yet.

PSA_ERROR_BUFFER_TOO_SMALL

The size of the `user_id` is too small.

psa_status_t psa_status_t psa_crypto_driver_pake_get_peer (const psa_crypto_driver_pake_inputs_t *inputs, uint8_t *peer_id, size_t peer_id_size, size_t *peer_id_length) psa_crypto_driver_pake_get_peer const psa_crypto_driver_pake_inputs_t * inputs uint8_t * peer_id size_t peer_id_size size_t * peer_id_length

Get the peer id from given inputs.

inputs

Operation inputs.

peer_id

Peer id.

peer_id_size

Size of `peer_id` in bytes.

peer_id_length

Size of the peer id in bytes.

PSA_SUCCESS

Success.

PSA_ERROR_BAD_STATE

Peer id hasn't been set yet.

PSA_ERROR_BUFFER_TOO_SMALL

The size of the `peer_id` is too small.

psa_status_t psa_status_t psa_crypto_driver_pake_get_cipher_suite (const psa_crypto_driver_pake_inputs_t *inputs, psa_pake_cipher_suite_t *cipher_suite) psa_crypto_driver_pake_get_cipher_suite const psa_crypto_driver_pake_inputs_t * inputs psa_pake_cipher_suite_t * cipher_suite

Get the cipher suite from given inputs.

inputs

Operation inputs.

cipher_suite

Return buffer for role.

PSA_SUCCESS

Success.

PSA_ERROR_BAD_STATE

Cipher_suite hasn't been set yet.

psa_status_t psa_status_t psa_pake_setup (psa_pake_operation_t *operation, const psa_pake_cipher_suite_t *cipher_suite) psa_pake_setup psa_pake_operation_t * operation const psa_pake_cipher_suite_t * cipher_suite

Set the session information for a password-authenticated key exchange.

The sequence of operations to set up a password-authenticated key exchange 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_pake_operation_t, e.g. PSA_PAKE_OPERATION_INIT.

3. Call psa_pake_setup() to specify the cipher suite.

4. Call `psa_pake_set_xxx()` functions on the operation to complete the setup. The exact sequence of `psa_pake_set_xxx()` functions that needs to be called depends on the algorithm in use.

Refer to the documentation of individual PAKE algorithm types (`PSA_ALG_XXX` values of type psa_algorithm_t such that PSA_ALG_IS_PAKE(`alg`) is true) for more information.

A typical sequence of calls to perform a password-authenticated key exchange:

1. Call psa_pake_output(operation, PSA_PAKE_STEP_KEY_SHARE, ...) to get the key share that needs to be sent to the peer.

2. Call psa_pake_input(operation, PSA_PAKE_STEP_KEY_SHARE, ...) to provide the key share that was received from the peer.

3. Depending on the algorithm additional calls to psa_pake_output() and psa_pake_input() might be necessary.

4. Call psa_pake_get_implicit_key() for accessing the shared secret.

Refer to the documentation of individual PAKE algorithm types (`PSA_ALG_XXX` values of type psa_algorithm_t such that PSA_ALG_IS_PAKE(`alg`) is true) for more information.

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

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

- A call to psa_pake_abort().

- A successful call to psa_pake_get_implicit_key().

operation

The operation object to set up. It must have been initialized but not set up yet.

cipher_suite

The cipher suite to use. (A cipher suite fully characterizes a PAKE algorithm and determines the algorithm as well.)

PSA_SUCCESS

Success.

PSA_ERROR_INVALID_ARGUMENT

The algorithm in `cipher_suite` is not a PAKE algorithm, or the PAKE primitive in `cipher_suite` is not compatible with the PAKE algorithm, or the hash algorithm in `cipher_suite` is invalid or not compatible with the PAKE algorithm and primitive.

PSA_ERROR_NOT_SUPPORTED

The algorithm in `cipher_suite` is not a supported PAKE algorithm, or the PAKE primitive in `cipher_suite` is not supported or not compatible with the PAKE algorithm, or the hash algorithm in `cipher_suite` is not supported or not compatible with the PAKE algorithm and primitive.

PSA_ERROR_COMMUNICATION_FAILURE

PSA_ERROR_CORRUPTION_DETECTED

PSA_ERROR_BAD_STATE

The operation state is not valid, 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_pake_set_password_key (psa_pake_operation_t *operation, mbedtls_svc_key_id_t password) psa_pake_set_password_key psa_pake_operation_t * operation mbedtls_svc_key_id_t password

Set the password for a password-authenticated key exchange from key ID.

Call this function when the password, or a value derived from the password, is already present in the key store.

operation

The operation object to set the password for. It must have been set up by psa_pake_setup() and not yet in use (neither psa_pake_output() nor psa_pake_input() has been called yet). It must be on operation for which the password hasn't been set yet (psa_pake_set_password_key() hasn't been called yet).

password

Identifier of the key holding the password or a value derived from the password (eg. by a memory-hard function). It must remain valid until the operation terminates. It must be of type PSA_KEY_TYPE_PASSWORD or PSA_KEY_TYPE_PASSWORD_HASH. It has to allow the usage PSA_KEY_USAGE_DERIVE.

PSA_SUCCESS

Success.

PSA_ERROR_INVALID_HANDLE

`password` is not a valid key identifier.

PSA_ERROR_NOT_PERMITTED

The key does not have the PSA_KEY_USAGE_DERIVE flag, or it does not permit the `operation's` algorithm.

PSA_ERROR_INVALID_ARGUMENT

The key type for `password` is not PSA_KEY_TYPE_PASSWORD or PSA_KEY_TYPE_PASSWORD_HASH, or `password` is not compatible with the `operation's` cipher suite.

PSA_ERROR_NOT_SUPPORTED

The key type or key size of `password` is not supported with the `operation's` cipher suite.

PSA_ERROR_COMMUNICATION_FAILURE

PSA_ERROR_CORRUPTION_DETECTED

PSA_ERROR_STORAGE_FAILURE

PSA_ERROR_DATA_CORRUPT

PSA_ERROR_DATA_INVALID

PSA_ERROR_BAD_STATE

The operation state is not valid (it must have been set up.), 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_pake_set_user (psa_pake_operation_t *operation, const uint8_t *user_id, size_t user_id_len) psa_pake_set_user psa_pake_operation_t * operation const uint8_t * user_id size_t user_id_len

Set the user ID for a password-authenticated key exchange.

Call this function to set the user ID. For PAKE algorithms that associate a user identifier with each side of the session you need to call psa_pake_set_peer() as well. For PAKE algorithms that associate a single user identifier with the session, call psa_pake_set_user() only.

Refer to the documentation of individual PAKE algorithm types (`PSA_ALG_XXX` values of type psa_algorithm_t such that PSA_ALG_IS_PAKE(`alg`) is true) for more information.

operation

The operation object to set the user ID for. It must have been set up by psa_pake_setup() and not yet in use (neither psa_pake_output() nor psa_pake_input() has been called yet). It must be on operation for which the user ID hasn't been set (psa_pake_set_user() hasn't been called yet).

user_id

The user ID to authenticate with.

user_id_len

Size of the `user_id` buffer in bytes.

PSA_SUCCESS

Success.

PSA_ERROR_INVALID_ARGUMENT

`user_id` is not valid for the `operation's` algorithm and cipher suite.

PSA_ERROR_NOT_SUPPORTED

The value of `user_id` is not supported by the implementation.

PSA_ERROR_INSUFFICIENT_MEMORY

PSA_ERROR_COMMUNICATION_FAILURE

PSA_ERROR_CORRUPTION_DETECTED

PSA_ERROR_BAD_STATE

The operation state is not valid, 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_pake_set_peer (psa_pake_operation_t *operation, const uint8_t *peer_id, size_t peer_id_len) psa_pake_set_peer psa_pake_operation_t * operation const uint8_t * peer_id size_t peer_id_len

Set the peer ID for a password-authenticated key exchange.

Call this function in addition to psa_pake_set_user() for PAKE algorithms that associate a user identifier with each side of the session. For PAKE algorithms that associate a single user identifier with the session, call psa_pake_set_user() only.

Refer to the documentation of individual PAKE algorithm types (`PSA_ALG_XXX` values of type psa_algorithm_t such that PSA_ALG_IS_PAKE(`alg`) is true) for more information.

operation

The operation object to set the peer ID for. It must have been set up by psa_pake_setup() and not yet in use (neither psa_pake_output() nor psa_pake_input() has been called yet). It must be on operation for which the peer ID hasn't been set (psa_pake_set_peer() hasn't been called yet).

peer_id

The peer's ID to authenticate.

peer_id_len

Size of the `peer_id` buffer in bytes.

PSA_SUCCESS

Success.

PSA_ERROR_INVALID_ARGUMENT

`peer_id` is not valid for the `operation's` algorithm and cipher suite.

PSA_ERROR_NOT_SUPPORTED

The algorithm doesn't associate a second identity with the session.

PSA_ERROR_INSUFFICIENT_MEMORY

PSA_ERROR_COMMUNICATION_FAILURE

PSA_ERROR_CORRUPTION_DETECTED

PSA_ERROR_BAD_STATE

Calling psa_pake_set_peer() is invalid with the `operation's` algorithm, the operation state is not valid, 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_pake_set_role (psa_pake_operation_t *operation, psa_pake_role_t role) psa_pake_set_role psa_pake_operation_t * operation psa_pake_role_t role

Set the application role for a password-authenticated key exchange.

Not all PAKE algorithms need to differentiate the communicating entities. It is optional to call this function for PAKEs that don't require a role to be specified. For such PAKEs the application role parameter is ignored, or PSA_PAKE_ROLE_NONE can be passed as `role`.

Refer to the documentation of individual PAKE algorithm types (`PSA_ALG_XXX` values of type psa_algorithm_t such that PSA_ALG_IS_PAKE(`alg`) is true) for more information.

operation

The operation object to specify the application's role for. It must have been set up by psa_pake_setup() and not yet in use (neither psa_pake_output() nor psa_pake_input() has been called yet). It must be on operation for which the application's role hasn't been specified (psa_pake_set_role() hasn't been called yet).

role

A value of type psa_pake_role_t indicating the application's role in the PAKE the algorithm that is being set up. For more information see the documentation of `PSA_PAKE_ROLE_XXX` constants.

PSA_SUCCESS

Success.

PSA_ERROR_INVALID_ARGUMENT

The `role` is not a valid PAKE role in the `operation’s` algorithm.

PSA_ERROR_NOT_SUPPORTED

The `role` for this algorithm is not supported or is not valid.

PSA_ERROR_COMMUNICATION_FAILURE

PSA_ERROR_CORRUPTION_DETECTED

PSA_ERROR_BAD_STATE

The operation state is not valid, 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_pake_output (psa_pake_operation_t *operation, psa_pake_step_t step, uint8_t *output, size_t output_size, size_t *output_length) psa_pake_output psa_pake_operation_t * operation psa_pake_step_t step uint8_t * output size_t output_size size_t * output_length

Get output for a step of a password-authenticated key exchange.

Depending on the algorithm being executed, you might need to call this function several times or you might not need to call this at all.

The exact sequence of calls to perform a password-authenticated key exchange depends on the algorithm in use. Refer to the documentation of individual PAKE algorithm types (`PSA_ALG_XXX` values of type psa_algorithm_t such that PSA_ALG_IS_PAKE(`alg`) is true) for more information.

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

operation

Active PAKE operation.

step

The step of the algorithm for which the output is requested.

output

Buffer where the output is to be written in the format appropriate for this `step`. Refer to the documentation of the individual `PSA_PAKE_STEP_XXX` constants for more information.

output_size

Size of the `output` buffer in bytes. This must be at least PSA_PAKE_OUTPUT_SIZE(`alg`, `primitive`, `output_step`) where `alg` and `primitive` are the PAKE algorithm and primitive in the operation's cipher suite, and `step` is the output step.

output_length

On success, the number of bytes of the returned output.

PSA_SUCCESS

Success.

PSA_ERROR_BUFFER_TOO_SMALL

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

PSA_ERROR_INVALID_ARGUMENT

`step` is not compatible with the operation's algorithm.

PSA_ERROR_NOT_SUPPORTED

`step` is not supported with the operation's algorithm.

PSA_ERROR_INSUFFICIENT_ENTROPY

PSA_ERROR_INSUFFICIENT_MEMORY

PSA_ERROR_COMMUNICATION_FAILURE

PSA_ERROR_CORRUPTION_DETECTED

PSA_ERROR_STORAGE_FAILURE

PSA_ERROR_DATA_CORRUPT

PSA_ERROR_DATA_INVALID

PSA_ERROR_BAD_STATE

The operation state is not valid (it must be active, and fully set up, and this call must conform to the algorithm's requirements for ordering of input and output steps), 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_pake_input (psa_pake_operation_t *operation, psa_pake_step_t step, const uint8_t *input, size_t input_length) psa_pake_input psa_pake_operation_t * operation psa_pake_step_t step const uint8_t * input size_t input_length

Provide input for a step of a password-authenticated key exchange.

Depending on the algorithm being executed, you might need to call this function several times or you might not need to call this at all.

The exact sequence of calls to perform a password-authenticated key exchange depends on the algorithm in use. Refer to the documentation of individual PAKE algorithm types (`PSA_ALG_XXX` values of type psa_algorithm_t such that PSA_ALG_IS_PAKE(`alg`) is true) for more information.

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

operation

Active PAKE operation.

step

The step for which the input is provided.

input

Buffer containing the input in the format appropriate for this `step`. Refer to the documentation of the individual `PSA_PAKE_STEP_XXX` constants for more information.

input_length

Size of the `input` buffer in bytes.

PSA_SUCCESS

Success.

PSA_ERROR_INVALID_SIGNATURE

The verification fails for a PSA_PAKE_STEP_ZK_PROOF input step.

PSA_ERROR_INVALID_ARGUMENT

`input_length` is not compatible with the `operation’s` algorithm, or the `input` is not valid for the `operation's` algorithm, cipher suite or `step`.

PSA_ERROR_NOT_SUPPORTED

`step` p is not supported with the `operation's` algorithm, or the `input` is not supported for the `operation's` algorithm, cipher suite or `step`.

PSA_ERROR_INSUFFICIENT_MEMORY

PSA_ERROR_COMMUNICATION_FAILURE

PSA_ERROR_CORRUPTION_DETECTED

PSA_ERROR_STORAGE_FAILURE

PSA_ERROR_DATA_CORRUPT

PSA_ERROR_DATA_INVALID

PSA_ERROR_BAD_STATE

The operation state is not valid (it must be active, and fully set up, and this call must conform to the algorithm's requirements for ordering of input and output steps), 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_pake_get_implicit_key (psa_pake_operation_t *operation, psa_key_derivation_operation_t *output) psa_pake_get_implicit_key psa_pake_operation_t * operation psa_key_derivation_operation_t * output

Get implicitly confirmed shared secret from a PAKE.

At this point there is a cryptographic guarantee that only the authenticated party who used the same password is able to compute the key. But there is no guarantee that the peer is the party it claims to be and was able to do so.

That is, the authentication is only implicit. Since the peer is not authenticated yet, no action should be taken yet that assumes that the peer is who it claims to be. For example, do not access restricted files on the peer's behalf until an explicit authentication has succeeded.

This function can be called after the key exchange phase of the operation has completed. It imports the shared secret output of the PAKE into the provided derivation operation. The input step PSA_KEY_DERIVATION_INPUT_SECRET is used when placing the shared key material in the key derivation operation.

The exact sequence of calls to perform a password-authenticated key exchange depends on the algorithm in use. Refer to the documentation of individual PAKE algorithm types (`PSA_ALG_XXX` values of type psa_algorithm_t such that PSA_ALG_IS_PAKE(`alg`) is true) for more information.

When this function returns successfully, `operation` becomes inactive. If this function returns an error status, both `operation` and `key_derivation` operations enter an error state and must be aborted by calling psa_pake_abort() and psa_key_derivation_abort() respectively.

operation

Active PAKE operation.

output

A key derivation operation that is ready for an input step of type PSA_KEY_DERIVATION_INPUT_SECRET.

PSA_SUCCESS

Success.

PSA_ERROR_INVALID_ARGUMENT

PSA_KEY_DERIVATION_INPUT_SECRET is not compatible with the algorithm in the `output` key derivation operation.

PSA_ERROR_NOT_SUPPORTED

Input from a PAKE is not supported by the algorithm in the `output` key derivation operation.

PSA_ERROR_INSUFFICIENT_MEMORY

PSA_ERROR_COMMUNICATION_FAILURE

PSA_ERROR_CORRUPTION_DETECTED

PSA_ERROR_STORAGE_FAILURE

PSA_ERROR_DATA_CORRUPT

PSA_ERROR_DATA_INVALID

PSA_ERROR_BAD_STATE

The PAKE operation state is not valid (it must be active, but beyond that validity is specific to the algorithm), or the library has not been previously initialized by psa_crypto_init(), or the state of `output` is not valid for the PSA_KEY_DERIVATION_INPUT_SECRET step. This can happen if the step is out of order or the application has done this step already and it may not be repeated. It is implementation-dependent whether a failure to initialize results in this error code.

psa_status_t psa_status_t psa_pake_abort (psa_pake_operation_t *operation) psa_pake_abort psa_pake_operation_t * operation

Abort a PAKE 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_pake_setup() again.

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

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

operation

The operation to abort.

PSA_SUCCESS

Success.

PSA_ERROR_COMMUNICATION_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_PAKE_ROLE_NONE
((psa_pake_role_t) 0x00)

A value to indicate no role in a PAKE algorithm. This value can be used in a call to psa_pake_set_role() for symmetric PAKE algorithms which do not assign roles.

PSA_PAKE_ROLE_FIRST
((psa_pake_role_t) 0x01)

The first peer in a balanced PAKE.

Although balanced PAKE algorithms are symmetric, some of them needs an ordering of peers for the transcript calculations. If the algorithm does not need this, both PSA_PAKE_ROLE_FIRST and PSA_PAKE_ROLE_SECOND are accepted.

PSA_PAKE_ROLE_SECOND
((psa_pake_role_t) 0x02)

The second peer in a balanced PAKE.

Although balanced PAKE algorithms are symmetric, some of them needs an ordering of peers for the transcript calculations. If the algorithm does not need this, either PSA_PAKE_ROLE_FIRST or PSA_PAKE_ROLE_SECOND are accepted.

PSA_PAKE_ROLE_CLIENT
((psa_pake_role_t) 0x11)

The client in an augmented PAKE.

Augmented PAKE algorithms need to differentiate between client and server.

PSA_PAKE_ROLE_SERVER
((psa_pake_role_t) 0x12)

The server in an augmented PAKE.

Augmented PAKE algorithms need to differentiate between client and server.

PSA_PAKE_PRIMITIVE_TYPE_ECC
((psa_pake_primitive_type_t) 0x01)

The PAKE primitive type indicating the use of elliptic curves.

The values of the `family` and `bits` fields of the cipher suite identify a specific elliptic curve, using the same mapping that is used for ECC (psa_ecc_family_t) keys.

(Here `family` means the value returned by psa_pake_cs_get_family() and `bits` means the value returned by psa_pake_cs_get_bits().)

Input and output during the operation can involve group elements and scalar values:

1. The format for group elements is the same as for public keys on the specific curve would be. For more information, consult the documentation of psa_export_public_key().

2. The format for scalars is the same as for private keys on the specific curve would be. For more information, consult the documentation of psa_export_key().

PSA_PAKE_PRIMITIVE_TYPE_DH
((psa_pake_primitive_type_t) 0x02)

The PAKE primitive type indicating the use of Diffie-Hellman groups.

The values of the `family` and `bits` fields of the cipher suite identify a specific Diffie-Hellman group, using the same mapping that is used for Diffie-Hellman (psa_dh_family_t) keys.

(Here `family` means the value returned by psa_pake_cs_get_family() and `bits` means the value returned by psa_pake_cs_get_bits().)

Input and output during the operation can involve group elements and scalar values:

1. The format for group elements is the same as for public keys on the specific group would be. For more information, consult the documentation of psa_export_public_key().

2. The format for scalars is the same as for private keys on the specific group would be. For more information, consult the documentation of psa_export_key().

PSA_PAKE_PRIMITIVE
pake_type
pake_family
pake_bits
((pake_bits & 0xFFFF) != pake_bits) ? 0 : \ ((psa_pake_primitive_t) (((pake_type) << 24 | \ (pake_family) << 16) | (pake_bits)))

Construct a PAKE primitive from type, family and bit-size.

pake_type

The type of the primitive (value of type psa_pake_primitive_type_t).

pake_family

The family of the primitive (the type and interpretation of this parameter depends on `pake_type`, for more information consult the documentation of individual psa_pake_primitive_type_t constants).

pake_bits

The bit-size of the primitive (Value of type `size_t`. The interpretation of this parameter depends on `pake_family`, for more information consult the documentation of individual psa_pake_primitive_type_t constants).

The constructed primitive value of type psa_pake_primitive_t. Return 0 if the requested primitive can't be encoded as psa_pake_primitive_t.

PSA_PAKE_STEP_KEY_SHARE
((psa_pake_step_t) 0x01)

The key share being sent to or received from the peer.

The format for both input and output at this step is the same as for public keys on the group determined by the primitive (psa_pake_primitive_t) would be.

For more information on the format, consult the documentation of psa_export_public_key().

For information regarding how the group is determined, consult the documentation PSA_PAKE_PRIMITIVE.

PSA_PAKE_STEP_ZK_PUBLIC
((psa_pake_step_t) 0x02)

A Schnorr NIZKP public key.

This is the ephemeral public key in the Schnorr Non-Interactive Zero-Knowledge Proof (the value denoted by the letter 'V' in RFC 8235).

The format for both input and output at this step is the same as for public keys on the group determined by the primitive (psa_pake_primitive_t) would be.

For more information on the format, consult the documentation of psa_export_public_key().

For information regarding how the group is determined, consult the documentation PSA_PAKE_PRIMITIVE.

PSA_PAKE_STEP_ZK_PROOF
((psa_pake_step_t) 0x03)

A Schnorr NIZKP proof.

This is the proof in the Schnorr Non-Interactive Zero-Knowledge Proof (the value denoted by the letter 'r' in RFC 8235).

Both for input and output, the value at this step is an integer less than the order of the group selected in the cipher suite. The format depends on the group as well:

- For Montgomery curves, the encoding is little endian.

- For everything else the encoding is big endian (see Section 2.3.8 of SEC 1: Elliptic Curve Cryptography at https://www.secg.org/sec1-v2.pdf).

In both cases leading zeroes are allowed as long as the length in bytes does not exceed the byte length of the group order.

For information regarding how the group is determined, consult the documentation PSA_PAKE_PRIMITIVE.

This is a proposed PAKE interface for the PSA Crypto API. It is not part of the official PSA Crypto API yet.

The content of this section is not part of the stable API and ABI of Mbed TLS and may change arbitrarily from version to version. Same holds for the corresponding macros PSA_ALG_CATEGORY_PAKE and PSA_ALG_JPAKE.