This algorithm replaces the pre-existing stream cipher algorithms.
The underlying stream cipher is determined by the key type.
Signed-off-by: Bence Szépkúti <bence.szepkuti@arm.com>
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>
In order to remove large buffers from the stack, the der data is written
into the same buffer that the pem is eventually written into, however
although the pem data is zero terminated, there is now data left in the
buffer after the zero termination, which can cause
mbedtls_x509_crt_parse to fail to parse the same buffer if passed back
in. Patches also applied to mbedtls_pk_write_pubkey_pem, and
mbedtls_pk_write_key_pem, which use similar methods of writing der data
to the same buffer, and tests modified to hopefully catch any future
regression on this.
Signed-off-by: Paul Elliott <paul.elliott@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 internal functions mbedtls_cipher_aead_{encrypt,decrypt} reject
unsupported algorithms, so there's no need for an additional check in
the legacy wrappers.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Make sure that if a buffer is allowed to be empty, a null pointer is
accepted if the buffer length is 0. This was already the case for most
but not all arguments to mbedtls_cipher_auth_{en,de}crypt{,_ext}.
Make sure to pass NULL for an empty buffer in the tests.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
fix_negative allocates memory for its result. The calling site didn't
check the return value, so an out-of-memory error could lead to an
incorrect calculation. Fix this.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
