If a random driver has a built-in entropy source and doesn't need an
external entropy source, make the driver author declare this
explicitly, rather than it being a less secure default.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
The get_random entry point was allowed to return partial data on both
PSA_SUCCESS and PSA_ERROR_INSUFFICIENT_ENTROPY, but there was no
meaningful difference between the two. Keep it simple: PSA_SUCCESS is
success but can be partial, and PSA_ERROR_INSUFFICIENT_ENTROPY is an
error with no output.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Explicitly recommend that the driver accounts for environmental
conditions that can affect the amount of entropy.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
A random generation driver does not need to support entropy injection.
This will limit it to platforms where the RNG peripheral is the sole
entropy source and without an RNG seed saved into persistent storage.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
If an RNG peripheral includes an entropy source, it would presumably
declare "initial_entropy_size" and "reseed_entropy_size" to be 0. In
this case, don't require the core to call "add_entropy".
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
The `get_entropy` entry point can be provided by multiple transparent
drivers, and the core will call all of them. But apart from that,
`get_entropy` doesn't involve an opaque key or a location, so it can
be in a transparent driver.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Transparent drivers may provide a DRBG interface through "add_entropy"
and "get_random" entry points. This interface may also be used with a
non-deterministic generator, for chips that include a TRNG.
Opaque driver may provide a "get_entropy" entry point.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Allow the core to call the "get_builtin_key" entry point to retrieve
the attributes of a built-in key. This is useful to implement
psa_get_key_attributes(), and also when the key data buffer's size
depends on the key type and size.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Having a time stamp identifying each revision of the document is
useful, but it's also a pain because it creates a conflict whenever
there are multiple pending changes at the same time. The gain isn't
worth the pain, so I'm removing the time stamp.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
The driver interfaces described in crypto_accel_driver.h and
crypto_entropy_driver.h are no longer being worked on. We do not
intend to finish the design of these interfaces or to implement them
in Mbed TLS. They have been superseded by the unified driver
interface (docs/proposed/psa-driver-interface.md), which is being
actively worked on both to finalize the specification and to implement
it in Mbed TLS.
The partially implemented dynamic secure element interface is staying
for now.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Rework the section describing key import, in particular to clarify key
size determination and checking. There is no intended semantic change.
Note an open question around support for implementation-specific
import formats.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
PSA_WANT_xxx is useful regardless of how the symbols are defined:
explicitly (with MBEDTLS_PSA_CRYPTO_CONFIG) or implicitly (without
MBEDTLS_PSA_CRYPTO_CONFIG).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Move all the PSA crypto APIs using key handles
to use key identifiers but psa_key_open() and
psa_key_close(). This is done without modifying
any test as key handles and key identifiers are
now the same.
Update the library modules using PSA crypto APIs
to get rid of key handles.
Programs and unit tests are updated to not use
key handles in subsequent commits, not in this
one.
Signed-off-by: Ronald Cron <ronald.cron@arm.com>
Now that transparent drivers have an "import_key" entry point, the key
creation interfaces for transparent drivers and opaque drivers are
very similar. Unify the sections that describe their behavior,
including key validation and key size determination.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
When importing a transparent key, the key needs to be not only
validated, but also possibly converted, if it is not already in the
canonical representation. So change the validate_key entry point to an
import_key entry point.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Without MBEDTLS_PSA_CRYPTO_CONFIG, PSA_WANT_xxx needs to be defined,
for the sake of code that calls the PSA API (TLS code, tests, sample
apps).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
* Stores bits in psa_persistent_key_storage_format.
* psa_load_persistent_key_into_slot still imports plaintext keys which
ensures that the bits value gets set.
* Updates key specification to match new implementation.
* Expands persistent store and load tests with to check for bits
attribute.
* Removes bits storage from psa_se_key_data_storage_t.
Signed-off-by: Torstein Nesse <torstein.nesse@silabs.com>
When importing a key, the code that parses the input needs to
determine the key size ("bits" attribute). This is specific to import
since other key creation methods require the caller to supply a size.
Therefore, add an extra output parameter `bits` to the "import_key"
entry point for opaque drivers. Likewise, add a `bits` output
parameter to the "validate_key" entry point for transparent drivers.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
With PSA crypto v1.0.0, a volatile key identifier may
contain a owner identifier but no file is associated
to it. Thus rename the type psa_key_file_id_t to
mbedtls_svc_key_id_t to avoid a direct link with a
file when a key identifier involves an owner
identifier.
The new type name is prefixed by mbedtls to highlight
that the type is specific to Mbed TLS implementation
and not defined in the PSA Cryptography API
specification.
The svc in the type name stands for service as this
is the key identifier type from the point of view of
the service providing the Cryptography services.
The service can be completely provided by the present
library or partially in case of a multi-client service.
As a consequence rename as well:
. MBEDTLS_PSA_CRYPTO_KEY_FILE_ID_ENCODES_OWNER to
MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER
. PSA_KEY_ID_INIT to MBEDTLS_SVC_KEY_ID_INIT
. PSA_KEY_FILE_GET_KEY_ID to MBEDTLS_SVC_KEY_ID_GET_KEY_ID
. psa_key_file_id_make to mbedtls_svc_key_id_make
Signed-off-by: Ronald Cron <ronald.cron@arm.com>
Proposed specification for conditional inclusion of cryptographic
mechanism through the PSA API in Mbed TLS.
The inclusion of a mechanism is based on a declaration of boolean
symbols by the application. There is a symbol for each key type or
parametrized key type constructor, and for each algorithm or
parametrized algorithm constructor.
This is work in progress, presented for a first design discussion.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
There is little point in leaving the order in which drivers are
considered unspecified. This gives flexibility to the implementation
for a process that is generally performed at build time, not in a
constrained environment. Having a well-defined order is especially
useful with fallback.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
It's ok if they map to the same function names and an error otherwise.
It's an error to have multiple opaque drivers for the same location.
If multiple transparent drivers apply, which one applies is unspecified.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
The existing description of the syntax of capabilities also describes
the semantics of each property, but the semantics of the capability as
a whole is not immediately clear. Add a subsection that explains
precisely when a capability is applicable.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Inferring entry points from algorithms is nice in that it makes
capability specifications shorter and less redundant, but that's not
really important. It also makes capabilities more fragile: if the core
starts supporting new mechanisms based on the same algorithm (for
example, adding hash-and-sign when only sign-the-hash existed before),
a driver only supporting the old mechanisms would fail at build time.
So make entry points mandatory.
This has the benefit of making the semantics of capabilities easier to
describe.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Add the mention of key_derivation_output_key in the section about the
key derivation entry point family.
Rename "derive_key" to "key_derivation_output_key". At this point,
there's no reason to deviate from the naming convention.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Clarify some sentences. There is no change in intended meaning.
Fix typos. Change British spelling to American spelling.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Locations aren't in the official PSA API specification yet (they've
only be made public in Mbed TLS). Until version 1.0.1 of the API
specification is out, this document needs to explain locations.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Rather than have some functions take the in-memory copy of the
persistent data as argument, allow all of them to access the
persistent data, including modifying it.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Opaque drivers only have a destroy function if the key is stored in
the secure element.
Expand on how key creation works. Provide more explanations of
allocate_key in drivers for secure elements with storage. Discuss key
destruction as well.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Call the functions listed in the driver description "entry points".
It's more precise than "functions", which could also mean any C
function defined in the driver code.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Driver developer's guide: introduction on how to write a driver.
Driver integration guide: how to build Mbed TLS with drivers.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Working draft of the PSA cryptography unified interface specification.
Eventually this document will be under Arm PSA architecture ownership,
but for the time being this draft is maintained in Mbed TLS.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Rename PSA_ECC_CURVE_xxx to PSA_ECC_FAMILY_xxx, also rename
PSA_KEY_TYPE_GET_CURVE to PSA_KEY_TYPE_ECC_GET_FAMILY and rename
psa_ecc_curve_t to psa_ecc_family_t. Old defines are provided in
include/crypto_compat.h for backward compatibility.
Signed-off-by: Paul Elliott <paul.elliott@arm.com>
