psa_drv_se_context_t Struct Reference
Driver context structure.
Public Member Functions
|const void *const||MBEDTLS_PRIVATE (persistent_data)|
|A read-only pointer to the driver's persistent data. |
|const size_t||MBEDTLS_PRIVATE (persistent_data_size)|
|The size of |
|Driver transient data. |
Driver context structure.
Driver functions receive a pointer to this structure. Each registered driver has one instance of this structure.
Implementations must include the fields specified here and may include other fields.
Member Function Documentation
◆ MBEDTLS_PRIVATE() [1/3]
|const void* const psa_drv_se_context_t::MBEDTLS_PRIVATE||(||persistent_data||)|
A read-only pointer to the driver's persistent data.
Drivers typically use this persistent data to keep track of which slot numbers are available. This is only a guideline: drivers may use the persistent data for any purpose, keeping in mind the restrictions on when the persistent data is saved to storage: the persistent data is only saved after calling certain functions that receive a writable pointer to the persistent data.
The core allocates a memory buffer for the persistent data. The pointer is guaranteed to be suitably aligned for any data type, like a pointer returned by
malloc (but the core can use any method to allocate the buffer, not necessarily
The size of this buffer is in the
persistent_data_size field of this structure.
Before the driver is initialized for the first time, the content of the persistent data is all-bits-zero. After a driver upgrade, if the size of the persistent data has increased, the original data is padded on the right with zeros; if the size has decreased, the original data is truncated to the new size.
This pointer is to read-only data. Only a few driver functions are allowed to modify the persistent data. These functions receive a writable pointer. These functions are:
The PSA Cryptography core saves the persistent data from one session to the next. It does this before returning from API functions that call a driver method that is allowed to modify the persistent data, specifically:
- psa_crypto_init() causes a call to psa_drv_se_t::p_init, and may call psa_drv_se_key_management_t::p_destroy to complete an action that was interrupted by a power failure.
- Key creation functions cause a call to psa_drv_se_key_management_t::p_allocate, and may cause a call to psa_drv_se_key_management_t::p_destroy in case an error occurs.
- psa_destroy_key() causes a call to psa_drv_se_key_management_t::p_destroy.
◆ MBEDTLS_PRIVATE() [2/3]
|const size_t psa_drv_se_context_t::MBEDTLS_PRIVATE||(||persistent_data_size||)|
The size of
persistent_data in bytes.
This is always equal to the value of the
persistent_data_size field of the psa_drv_se_t structure when the driver is registered.
◆ MBEDTLS_PRIVATE() [3/3]
Driver transient data.
The core initializes this value to 0 and does not read or modify it afterwards. The driver may store whatever it wants in this field.