When generating keys that have persistent lifetime, we will need
the keys to be in the exported format to save to persistent storage.
This refactoring to separate checking the slots usage from the
exporting of the key data will be necessary for using
psa_internal_export_key in psa_generate_key.
Allow use of persistent keys, including configuring them, importing and
exporting them, and destroying them.
When getting a slot using psa_get_key_slot, there are 3 scenarios that
can occur if the keys lifetime is persistent:
1. Key type is PSA_KEY_TYPE_NONE, no persistent storage entry:
- The key slot is treated as a standard empty key slot
2. Key type is PSA_KEY_TYPE_NONE, persistent storage entry exists:
- Attempt to load the key from persistent storage
3. Key type is not PSA_KEY_TYPE_NONE:
- As checking persistent storage on every use of the key could
be expensive, the persistent key is assumed to be saved in
persistent storage, the in-memory key is continued to be used.
Create a new function psa_remove_key_from_memory() from psa_destroy_key().
This is needed as psa_destroy_key() will remove all key data, including
persistent storage. mbedtls_psa_crypto_free() will now only free in-memory
data and not persistent data.
Create a new function psa_import_key_into_slot() from psa_import_key().
This is common functionality that will be used both when importing a
key and loading a key from persistent storage.
Add a magic header to the storage format used with files. The
header is used as an initial check that the data is what we expect,
rather than garbage data.
Add new functions, psa_load_persistent_key(),
psa_free_persistent_key_data(), and psa_save_persistent_key(), for
managing persistent keys. These functions load to or save from our
internal representation of key slots. Serialization is a concern of the
storage backend implementation and doesn't abstraction-leak into the
lifetime management code.
An initial implementation for files is provided. Additional storage
backends can implement this interface for other storage types.
The persistent key implementation will be split across multiple
files as it will eventually be implementing multiple storage
backends. As these internal functions will need to be callable by
other files, we will add the headers in the library folder. This
commit adds this include location to the necessary scripts.
For tests, the library is added as an include location as testing
on-target with Mbed OS is not possible with paths including ".."
This commit adds the default upstream configuration to the set of
tests we run on CI, which was long overdue.
config-default is a copy of the Mbed TLS upstream config.h. It's
useful for two things: to compare our local changes to
include/mbedtls/config.h, and to test that we aren't breaking the
default upstream configuration.
Run a subset of the TLS tests that focus on exercising cryptographic
algorithms as used from TLS. Don't run the full set of TLS tests
because they're unlikely to be affected by changes in the PSA branch.
Upstream mbedtls maintains the default configuration in
include/mbedtls/config.h. We maintain the default configuration in
configs/config-default.h, and our PSA-specific configuration in
include/mbedtls/config.h. This means, each time we update Mbed TLS, we need
to update the default configuration file (configs/config-default.h)
manually using the copy from mbedtls.
Mbed TLS version 2.14.0
Resolved conflicts in include/mbedtls/config.h,
tests/scripts/check-files.py, and yotta/create-module.sh by removing yotta.
Resolved conflicts in tests/.jenkins/Jenkinsfile by continuing to run
mbedtls-psa job.
There was no test case of ECDH with anything other than
PSA_ALG_SELECT_RAW. Exercise the code path from ECDH through a
"proper" KDF.
ECDH shared secret copied from an existing test, HKDF output
calculated with Cryptodome.
If psa_key_derivation_internal() fails, it's up to the caller to clean
up. Do this, and add a note at the top of
psa_key_derivation_internal() and its auxiliary functions.
There is no non-regression test because at the moment the only way to
trigger an error is a borderline low-memory condition and we don't
have the means to trigger this.
Add missing checks for defined(MBEDTLS_MD_C) around types and
functions that require it (HMAC, HKDF, TLS12_PRF).
Add missing checks for defined(MBEDTLS_ECDSA_DETERMINISTIC) around
code that calls mbedtls_ecdsa_sign_det().
Add missing checks for defined(MBEDTLS_ECDH_C) around ECDH-specific
functions.
The standard prohibits calling memcpy() with NULL pointer
arguments, even if the size argument is 0.
The TLS-1.2 PRF generator setup function previously called
memcpy() with the label and salt as the source, even if
they were of length 0, as exercised by the derive_key_policy
test case in the PSA crypto test suite.
This commit adds guards around the memcpy() calls so that they
are only executed of salt or label have positive length, respectively.
This commit adds KDF algorithm identifiers `PSA_ALG_TLS12_PRF(HASH)`
to the PSA crypto API. They represent the key derivation functions
used by TLS 1.2 for the PreMasterSecret->MasterSecret and
MasterSecret->KeyBlock conversions.
Use m for the bit size of the field order, not q which is
traditionally the field order.
Correct and clarify the private key representation format as has been
done for the private key and ECDH shared secret formats.
The endianness actually depends on the curve type.
Correct the terminology around "curve size" and "order of the curve".
I tried to find a formulation that is comprehensible to programmers
who do not know the underlying mathematics, but nonetheless correct
and precise.
Use similar terminology in other places that were using "order of the
curve" to describe the bit size associated with the curve.
In psa_key_agreement_ecdh, check that the public key is on the same
curve as the private key. The underlying mbedtls API doesn't check.
If the curves don't match, psa_key_agreement_ecdh is practically
guaranteed to return INVALID_ARGUMENT anyway, because way the code is
written, the public point is interpreted on the curve of the private
point, and it is rejected because the point is not on the curve. This
is why the test case "PSA key agreement setup: ECDH, raw: public key
on different curve" passed even before adding this check.
