Document the maximum key identifier

Give it a name and explain why it was chosen.
This commit is contained in:
Gilles Peskine 2018-12-10 17:30:29 +01:00
parent 039b90cf5b
commit 48868129cd
2 changed files with 18 additions and 1 deletions

View File

@ -871,7 +871,7 @@ psa_status_t psa_internal_make_key_persistent( psa_key_handle_t handle,
return( PSA_ERROR_INVALID_ARGUMENT ); return( PSA_ERROR_INVALID_ARGUMENT );
/* Reject high values because the file names are reserved for the /* Reject high values because the file names are reserved for the
* library's internal use. */ * library's internal use. */
if( id >= 0xffff0000 ) if( id >= PSA_MAX_PERSISTENT_KEY_IDENTIFIER )
return( PSA_ERROR_INVALID_ARGUMENT ); return( PSA_ERROR_INVALID_ARGUMENT );
status = psa_get_key_slot( handle, &slot ); status = psa_get_key_slot( handle, &slot );

View File

@ -44,6 +44,23 @@ extern "C" {
* inadvertently store an obscene amount of data) */ * inadvertently store an obscene amount of data) */
#define PSA_CRYPTO_MAX_STORAGE_SIZE ( 30 * 1024 ) #define PSA_CRYPTO_MAX_STORAGE_SIZE ( 30 * 1024 )
/** The maximum permitted persistent slot number.
*
* In Mbed Crypto 0.1.0b:
* - Using the file backend, all key ids are ok except 0.
* - Using the ITS backend, all key ids are ok except 0xFFFFFF52
* (#PSA_CRYPTO_ITS_RANDOM_SEED_UID) for which the file contains the
* device's random seed (if this feature is enabled).
* - Only key ids from 1 to #PSA_KEY_SLOT_COUNT are actually used.
*
* Since we need to preserve the random seed, avoid using that key slot.
* Reserve a whole range of key slots just in case something else comes up.
*
* This limitation will probably become moot when we implement client
* separation for key storage.
*/
#define PSA_MAX_PERSISTENT_KEY_IDENTIFIER 0xffff0000
/** /**
* \brief Format key data and metadata and save to a location for given key * \brief Format key data and metadata and save to a location for given key
* slot. * slot.