If the key doesn't exist by the time this call is made
then the handle is invalid,
which means that PSA_ERROR_INVALID_HANDLE should be
returned rather than "does not exist"
It may be possible that the implementation runs out of
memory when exporting a key from storage or a secure
element. For example, it may not be possible to directly
move the data from storage to the caller, so the implementation
will have to buffer the material temporarily (an issue if dynamic
memory allocation scheme is used). For a large key
this is more likely to return.
It may be possible that an implementation does not
fetch key material until a command like
this is called and such an error may occur if an
off-chip secure storage dependency may have been wiped.
Note that PSA_ERROR_NOT_PERMITTED is not included
because I can't think of a scenario where you have
a valid key handle but aren't allowed to read the
attributes
Avoid compiler errors when MBEDTLS_PSA_CRYPTO_KEY_FILE_ID_ENCODES_OWNER
is set by using the application ID type.
[Error] psa_crypto_slot_management.c@175,9: used type 'psa_key_id_t' (aka 'psa_key_file_id_t') where arithmetic or pointer type is required
A macro useful for initializing psa_key_id_t, whether
MBEDTLS_PSA_CRYPTO_KEY_FILE_ID_ENCODES_OWNER is set or not. Without this
macro, it is necessary to know if
MBEDTLS_PSA_CRYPTO_KEY_FILE_ID_ENCODES_OWNER as with it the key ID is
non-scalar and needs to be initialized with {0, 0}, and 0 otherwise when
key ID is scalar.
Adjust the wording to permit multiple handles to a single key - closing
a handle does not necessarily release volatile memory associated with
the key, that only occurs when the last handle is closed.
- Describe the implementation defined behavior for opening multiple
keys, and provide a reference to the relevant section.
- Describe the use of INSUFFICENT_MEMORY error to indicate additional
implementation resource constaints.
- Clarify the distinction between DOES_NOT_EXIST and INVALID_HANDLE
error conditions.
Avoid an error with differing linkages being expressed for
psa_set_key_domain_parameters() between crypto_extra.h and
crypto_struct.h in C++ builds.
[Error] crypto_extra.h@456,14: conflicting declaration of 'psa_status_t psa_set_key_domain_parameters(psa_key_attributes_t*, psa_key_type_t, const uint8_t *, size_t)' with 'C' linkage
The methods to import and generate a key in a secure element drivers
were written for an earlier version of the application-side interface.
Now that there is a psa_key_attributes_t structure that combines all
key metadata including its lifetime (location), type, size, policy and
extra type-specific data (domain parameters), pass that to drivers
instead of separate arguments for each piece of metadata. This makes
the interface less cluttered.
Update parameter names and descriptions to follow general conventions.
Document the public-key output on key generation more precisely.
Explain that it is optional in a driver, and when a driver would
implement it. Declare that it is optional in the core, too (which
means that a crypto core might not support drivers for secure elements
that do need this feature).
Update the implementation and the tests accordingly.
Register an existing key in a secure element.
Minimal implementation that doesn't call any driver method and just
lets the application declare whatever it wants.
Pass the key creation method (import/generate/derive/copy) to the
driver methods to allocate or validate a slot number. This allows
drivers to enforce policies such as "this key slot can only be used
for keys generated inside the secure element".
