The idiom "resize an mpi to a given size" appeared 4 times. Unify it
in a single function. Guarantee that the value is set to 0, which is
required by some of the callers and not a significant expense where
not required.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Since the internal function mpi_fill_random_internal() assumes that X
has the right size, there is no need to call grow().
To further simplify the function, set the sign outside, and zero out
the non-randomized part directly.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
In real life, min << N and the probability that mbedtls_mpi_random()
fails to find a suitable value after 30 iterations is less than one in
a billion. But at least for testing purposes, it's useful to not
outright reject "silly" small values of N, and for such values, 30
iterations is not enough to have a good probability of success.
Pick 250 iterations, which is enough for cases like (min=3, N=4), but
not for cases like (min=255, N=256).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This comment is no longer in the specific context of generating a
random point on an elliptic curve.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
mbedtls_mpi_random() uses mbedtls_mpi_cmp_mpi_ct(), which requires its
two arguments to have the same storage size. This was not the case
when the upper bound passed to mbedtls_mpi_random() had leading zero
limbs.
Fix this by forcing the result MPI to the desired size. Since this is
not what mbedtls_mpi_fill_random() does, don't call it from
mbedtls_mpi_random(), but instead call a new auxiliary function.
Add tests to cover this and other conditions with varying sizes for
the two arguments.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Instead of generating blinding values and keys in a not-quite-uniform way
(https://github.com/ARMmbed/mbedtls/issues/4245) with copy-pasted code,
use mbedtls_mpi_random().
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
dhm_make_common includes a piece of code that is identical to
dhm_random_below except for returning a different error code in one
case. Call dhm_random_below instead of repeating the code.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
P-1 is as bad as 1 as a blinding value. Don't accept it.
The chance that P-1 would be randomly generated is infinitesimal, so
this is not a practical issue, but it makes the code cleaner. It was
inconsistent to accept P-1 as a blinding value but not as a private key.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Unify the common parts of mbedtls_dhm_make_params and mbedtls_dhm_make_public.
No intended behavior change, except that the exact error code may
change in some corner cases which are too exotic for the existing unit
tests.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Instead of generating blinding values in a not-quite-uniform way
(https://github.com/ARMmbed/mbedtls/issues/4245) with copy-pasted
code, use mbedtls_mpi_random().
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Since mbedtls_mpi_random() is not specific to ECC code, move it from
the ECP module to the bignum module.
This increases the code size in builds without short Weierstrass
curves (including builds without ECC at all) that do not optimize out
unused functions.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Rename mbedtls_ecp_gen_privkey_sw to mbedtls_mpi_random since it has
no particular connection to elliptic curves beyond the fact that its
operation is defined by the deterministic ECDSA specification. This is
a generic function that generates a random MPI between 1 inclusive and
N exclusive.
Slightly generalize the function to accept a different lower bound,
which adds a negligible amount of complexity.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
mbedtls_ecp_gen_privkey_mx generates a random number with a certain
top bit set. Depending on the size, it would either generate a number
with that top bit being random, then forcibly set the top bit to
1 (when high_bit is not a multiple of 8); or generate a number with
that top bit being 0, then set the top bit to 1 (when high_bit is a
multiple of 8). Change it to always generate the top bit randomly
first.
This doesn't make any difference in practice: the probability
distribution is the same either way, and no supported or plausible
curve has a size of the form 8n+1 anyway. But it slightly simplifies
reasoning about the behavior of this function.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Don't calculate the bit-size of the initially generated random number.
This is not necessary to reach the desired distribution of private
keys, and creates a (tiny) side channel opportunity.
This changes the way the result is derived from the random number, but
does not affect the resulting distribution.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
The library rejected an RNG input of all-bits-zero, which led to the
key 2^{254} (for Curve25519) having a 31/32 chance of being generated
compared to other keys. This had no practical impact because the
probability of non-compliance was 2^{-256}, but needlessly
complicated the code.
The exception was added in 98e28a74e3 to
avoid the case where b - 1 wraps because b is 0. Instead, change the
comparison code to avoid calculating b - 1.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
For Montgomery keys, n_bits is actually the position of the highest
bit and not the number of bits, which would be 1 more (fence vs
posts). Rename the variable accordingly to lessen the confusion.
No semantic change.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Put the Montgomery and short Weierstrass implementations of
mbedtls_ecp_gen_privkey into their own function which can be tested
independently, but will not be part of the public ABI/API.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
When mbedtls_nist_kw_wrap was called with output=NULL and out_size=0, it
performed arithmetic on the null pointer before detecting that the output
buffer is too small and returning an error code. This was unlikely to have
consequences on real-world hardware today, but it is undefined behavior and
UBSan with Clang 10 flagged it. So fix it (fix#4025).
Fix a similar-looking pattern in unwrap, though I haven't verified that it's
reachable there.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
The persistence level PSA_KEY_PERSISTENCE_READ_ONLY can now only be used
as intended, for keys that cannot be modified through normal use of the API.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
mbedtls_psa_get_stats() was written back before lifetimes were
structured as persistence and location. Fix its classification of
volatile external keys and internal keys with a non-default
persistence.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
On space-constrained platforms, it is a useful configuration to be able
to import/export and perform RSA key pair operations, but to exclude RSA
key generation, potentially saving flash space. It is not possible to
express this with the PSA_WANT_ configuration system at the present
time. However, in previous versions of Mbed TLS (v2.24.0 and earlier) it
was possible to configure a software PSA implementation which was
capable of making RSA signatures but not capable of generating RSA keys.
To do this, one unset MBEDTLS_GENPRIME.
Since the addition of MBEDTLS_PSA_BUILTIN_KEY_TYPE_RSA_KEY_PAIR, this
expressivity was lost. Expressing that you wanted to work with RSA key
pairs forced you to include the ability to generate key pairs as well.
Change psa_crypto_rsa.c to only call mbedtls_rsa_gen_key() if
MBEDTLS_GENPRIME is also set. This restores the configuration behavior
present in Mbed TLS v2.24.0 and earlier versions.
It left as a future exercise to add the ability to PSA to be able to
express a desire for a software or accelerator configuration that
includes RSA key pair operations, like signature, but excludes key pair
generation.
Without this change, linker errors will occur when attempts to call,
which doesn't exist when MBEDTLS_GENPRIME is unset.
psa_crypto_rsa.c.obj: in function `rsa_generate_key':
psa_crypto_rsa.c:320: undefined reference to `mbedtls_rsa_gen_key'
Fixes#4512
Signed-off-by: Jaeden Amero <jaeden.amero@arm.com>
TLS code specific to SHA-384 was gated on MBEDTLS_SHA512_C. But SHA-384 also
requires that MBEDTLS_SHA512_NO_SHA384 is not defined. This lead to dead
code in TLS when MBEDTLS_SHA512_C and MBEDTLS_SHA512_NO_SHA384 were both
defined (i.e. when SHA-512 was enabled but not SHA-384).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
They depended on MBEDTLS_SHA512_C only. A check for !MBEDTLS_SHA512_NO_SHA384
was missing.
Fix#4499.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
The sequence of calls starts-update-starts-update-finish is not a
guaranteed valid way to abort an operation and start a new one. Our
software implementation just happens to support it, but alt
implementations may very well not support it.
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
Session-ID based session resumption requires that the resumed session
is consistent with the client's ClientHello in terms of choice of
ciphersuite and choice of compression.
This check was previously assumed to be performed in the session cache
implementation, which seems wrong: The session cache should be an id-based
lookup only, and protocol specific checks should be left to Mbed TLS.
This commit
- adds an explicit ciphersuite and compression consistency check after
the SSL session cache has been queried
- removes the ciphersuite and compression consistency check from
Mbed TLS' session cache reference implementation.
Don't use ssl_check_xxx() for functions with void return
Signed-off-by: Hanno Becker <hanno.becker@arm.com>
Prepare to isolate the Montgomery and short Weierstrass
implementations of mbedtls_ecp_gen_privkey into their own function.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
A previous fix in d596ca8a1e worked with
beta versions of GCC 11, but not with the final 11.1 release.
This time, just disable the warning locally.
Fix#4130
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Zephyr's native posix port define _POSIX_C_SOURCE with a higher value
during the build, so when mbedTLS defines it with a different value
breaks the build.
As Zephyr is already defining a higher value is guaranteed that mbedTLS
required features will be available. So, just define it in case it was
not defined before.
[taken from Zephyr mbedtls module:
76dcd6eeca]
Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>
Signed-off-by: David Brown <david.brown@linaro.org>
Since they became equivalent after moving the is_sign checking back to
the PSA core, they're now redundant, and the generic mac_setup function
can just be called directly.
Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
Since a valid mac operation context would guarantee that the stored
mac size is >= 4, it wasn't immediately obvious that the zero-length
check is meant for static analyzers and a bit of robustness.
Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
The PSA core checks the key type and algorithm combination before
calling the driver, so the driver doesn't have to do this once more.
The PSA core will also not start an operation with a requested length
which is larger than the full MAC output size, so the output length check
in the driver isn't needed as long as the driver returns an error on
mac_setup if it doesn't support the underlying hash algorithm.
Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
It makes sense to do the length checking in the core rather than expect
each driver to deal with it themselves. This puts the onus on the core to
dictate which algorithm/key combinations are valid before calling a driver.
Additionally, this commit also updates the psa_mac_sign_finish function
to better deal with output buffer sanitation, as per the review comments
on #4247.
Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
As psa_mac_sign_finish / psa_mac_verify_finish already checks that the
operation structure is valid (id is non-zero), the driver itself doesn't
have to check for that anymore. If the operation has a driver ID assigned,
it means that driver has returned success from its setup function, so the
algorithm value will be set correctly.
Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
The key passed to the driver has been imported by the PSA Core, meaning
its length has already been verified, and the driver can rely on the
buffer length and key attributes being consistent.
Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
This means there is no longer a need to have an internal HMAC API, so
it is being removed in this commit as well.
Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
Prefix with 'mbedtls_psa' as per the other types which implement some
sort of algorithm in software.
Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
Now renamed to mbedtls_psa_safer_memcmp, it provides a single location
for buffer comparison.
Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
The purpose of key_set was to guard the operation structure from being
used for update/finish before a key was set. Now that the implementation
fully adheres to the PSA API, that function is covered by the `alg`
variable instead. It's set to the algorithm in use when a key is set, and
is zero when the operation is reset/invalid.
Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
* Early return since there's nothing to clean up
* Get rid of unnecessary local variable
* Check algorithm validity for MAC in the PSA core instead of in the driver
Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
Apparently it was at some point assumed that there would be
support for MAC algorithms with IV, but that hasn't been
implemented yet. Until that time, these context structure
members are superfluous and can be removed.
Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
Typedef'ed structures are suffixed _t
Also updated the initialiser macro with content that actually
matches the structure's content.
Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
Since HMAC moved into its own compilation unit, the internal API needed
to be documented and finalized. This means no more reaching deep into
the operation structure from within the PSA Crypto core. This will make
future refactoring work easier, since internal HMAC is now opaque to the
core.
Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
Step 3/x in moving the driver. Separate commits should make for easier
review.
Additional changes on top of code movement:
* Copied the implementation of safer_memcmp from psa_crypto into
psa_cipher_mac since the mac_verify driver implementation
depends on it, and it isn't available through external linkage
Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
Step 2/x in moving the driver. Separate commits should make for easier
review.
Additional changes on top of code movement:
* Early-return success on input with zero-length to mac_update, to
avoid NULL pointers getting passed into the driver dispatch
Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
Step 1/x in moving the driver. Separate commits should make for easier
review.
Additional changes on top of just moving code:
* Added a sanity check on the key buffer size for CMAC.
* Transfered responsibility for resetting the core members of the
PSA MAC operation structure back to the core (from the driver
wrapper layer)
Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
This is a temporary measure. Other operations in the PSA Core which rely
on this internal HMAC API should be rewritten to use the MAC API instead,
since they can then leverage accelerated HMAC should a platform provide
such acceleration support.
Signed-off-by: Steven Cooreman <steven.cooreman@silabs.com>
The changed logic is to try a sign-message driver (opaque or transparent);
if there isn't one, fallback to builtin sofware and do the hashing,
then try a sign-hash driver. This will enable to the opaque driver
to fallback to software.
Signed-off-by: gabor-mezei-arm <gabor.mezei@arm.com>
To avoid code duplication of the old-style SE interface usage
call psa_driver_wrapper_sign/verify_hash function instead of
the direct internal functions.
Signed-off-by: gabor-mezei-arm <gabor.mezei@arm.com>
Use common funtion for psa_sign_hash and psa_sign_message and one for
psa_verify_hash and psa_verify_message to unify them.
Signed-off-by: gabor-mezei-arm <gabor.mezei@arm.com>
Move the key buffer size calculation code under
tests to avoid check-names.sh to complain about
"likely macros with typos".
This removes the calculation of key buffer
sizes for the test driver from the wrapper based on
static size data. But the code is still there in test
code to be used when we go back to work on the
generation of the driver wrapper.
Signed-off-by: Ronald Cron <ronald.cron@arm.com>
