The requirement of minimum 15 bytes for output buffer in
psa_aead_finish() and psa_aead_verify() does not apply
to the built-in implementation of the GCM.
Alternative implementations are expected to verify the
length of the provided output buffers and to return
the MBEDTLS_ERR_GCM_BUFFER_TOO_SMALL in case the
buffer length is too small.
Signed-off-by: Mateusz Starzyk <mateusz.starzyk@mobica.com>
This option only gated an ability to set a callback,
but was deemed unnecessary as it was yet another define to
remember when writing tests, or test configurations. Fixes#4653.
Signed-off-by: Andrzej Kurek <andrzej.kurek@arm.com>
MBEDTLS_CHECK_RETURN_TYPICAL defaults off, but is enabled if
MBEDTLS_CHECK_RETURN_WARNING is enabled at compile time.
(MBEDTLS_CHECK_RETURN_CRITICAL is always enabled.)
The default is off so that a plausible program that builds with one version
of Mbed TLS in the default configuration will still build under the next
version.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Combine the changelog entries for the memory constraints fix on
aarch64 and amd64, since these are essentially fixing the same
issue.
Signed-off-by: David Horstmann <david.horstmann@arm.com>
Also fiixed the following merge problems:
crypto_struct.h : Added MBEDTLS_PRIVATE to psa_aead_operation_s
members (merge conflict)
psa_crypto_aead.c : Added ciphertext_length to mbedtls_gcm_finish
call (change of API during development)
Signed-off-by: Paul Elliott <paul.elliott@arm.com>
Add memory constraints to the aarch64 inline assembly in MULADDC_STOP.
This fixes an issue where Clang 12 and 13 were generating
non-functional code on aarch64 platforms. See #4962, #4943
for further details.
Signed-off-by: David Horstmann <david.horstmann@arm.com>
MULADDC_CORE reads from (%%rsi) and writes to (%%rdi). This fragment is
repeated up to 16 times, and %%rsi and %%rdi are s and d on entry
respectively. Hence the complete asm statement reads 16 64-bit words
from memory starting at s, and writes 16 64-bit words starting at d.
Without any declaration of modified memory, Clang 12 and Clang 13 generated
non-working code for mbedtls_mpi_mod_exp. The constraints make the unit
tests pass with Clang 12.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This parameter was set but not used, which was pointless. Clang 14 detects
this and legitimately complains.
Remove the parameter. This is an internal function, only called once. The
caller already has a sufficient check on the output buffer size which
applies in more cases, so there is no real gain in robustness in adding the
same check inside the internal function.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Conflicts:
library/ccm.c
Conflict resolved by re-applying the MBEDTLS_BYTE_0 macro.
Conflict resolved by ignoring the MBEDTLS_PUT_UINT16_BE macro
used in development branch on the 'b' buffer, because the 'b'
buffer is removed in current branch.
The numerical identifier of the CID extension hasn't been settled yet
and different implementations use values from different drafts. Allow
configuring the value at compile time.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
The makefiles look for python3 on Unix-like systems where python is often
Python 2. This uses sh code so it doesn't work on Windows. On Windows, the
makefiles just assume that python is Python 3.
The code was incorrectly deciding not to try python3 based on WINDOWS_BUILD,
which indicates that the build is *for* Windows. Switch to checking WINDOWS,
which indicates that the build is *on* Windows.
Fix#4774
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
The functions mbedtls_pk_sign(), mbedtls_pk_sign_restartable(),
mbedtls_ecdsa_write_signature() and mbedtls_ecdsa_write_signature_restartable()
now take an extra parameter indicating the size of the output buffer for the
signature.
No change to RSA because for RSA, the output size is trivial to calculate.
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>
* development: (66 commits)
Document the return type change in the migration guide
Fix return type of example key export callbacks
Add change log
psa: mac: Add driver dispatch tests for psa_mac_verify
psa: mac: Add driver delegation support for psa_mac_verify()
psa: mac: Introduce psa_mac_compute_internal
psa: mac: Add driver dispatch tests for psa_mac_compute
psa: mac: Improve MAC finalization code
psa: mac: Add driver delegation support for psa_mac_compute()
psa: mac: Add MAC compute builtin implementation
psa: mac: Improve implementation of psa_mac_finalize_alg_and_key_validation()
psa: mac: Split psa_mac_setup()
psa: mac: Re-organize psa_mac_setup() internal function
Move export callback and context to the end of SSL context
Improve ChangeLog wording for key export
Remove return value from key export callback
Make key export callback and context connection-specific
Remove all occurrences of TLS < 1.2 PRF identifier
Remote key export identifier used for TLS < 1.2.
Add missing documentation for key export callback parameters
...
mbedtls_mpi_read_binary{,_le} (in https://github.com/ARMmbed/mbedtls/pull/4276)
and mbedtls_mpi_read_string (in https://github.com/ARMmbed/mbedtls/pull/4644)
changed their behavior on an empty input from constructing an MPI object with
one limb to not allocating a limb. In principle, this change should be
transparent to applications, however it caused a bug in the library and it does
affect the value when writing back out, so list the change in the changelog.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
In Mbed TLS 2.26.0, the bug was hard to trigger, since all methods for
parsing a bignum (mbedtls_mpi_read_xxx functions) constructed an mbedtls_mpi
object with at least one limb.
In the development branch, after the commit
"New internal function mbedtls_mpi_resize_clear", this bug could be
triggered by a TLS server, by passing invalid custom Diffie-Hellman
parameters with G=0 transmitted as a 0-length byte string.
Since the behavior change in mbedtls_mpi_read_binary and
mbedtls_mpi_read_binary_le (constructing 0 limbs instead of 1 when passed
empty input) turned out to have consequences despite being in principle an
internal detail, mention it in the changelog.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
* development: (236 commits)
Changing the key length to 32 bytes in one of the PSA cipher setup tests
Removal of RC4 certs and fixes to docs and tests
Fix fd range for select on Windows
Refactor file descriptor checks into a common function
Removing global variable and moving variant function comment block
Fix typo in doc'n of session resumption API
Code review fixes
Fix warning in some configurations
Fix cmake build of fuzz_privkey
Fix async support in ssl_server2
Improve ChangeLog and migration guide entries
Use a proper DRBG in programs
Use the dedicated dummy_random in fuzzing programs
Fix cmake build of programs
Add ChangeLog and migration guide entries
Simplify internal code
Remove "internal RNG" code from ECP
Remove config option MBEDTLS_ECP_NO_INTERNAL_RNG
Add RNG params to private key parsing
Add RNG parameter to check_pair functions
...
- “Fix an issue where X happens” → ”Fix X“
the extra words are just a distraction.
- “resource” → “a resource”
- “where resource is never freed” has a name: it's a resource leak
- “when running one particular test suite” → “in a test suite”
Signed-off-by: Joe Subbiani <joe.subbiani@arm.com>
Fix mbedtls_net_poll() and mbedtls_net_recv_timeout() often failing with
MBEDTLS_ERR_NET_POLL_FAILED on Windows: they were testing that the file
descriptor is in range for fd_set, but on Windows socket descriptors are not
limited to a small range. Fixes#4465.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
The original formatting was in dos and the changelog
assembler would fail. The length of the description was
too long horizontally. This has been updated.
Signed-off-by: Joe Subbiani <joe.subbiani@arm.com>
Entries in ChangeLog and Migration guide files
have been merged to cover both the removal of
MBEDTLS_SSL_TRUNCATED_HMAC and
MBEDTLS_SSL_TRUNCATED_HMAC_COMPAT.
Signed-off-by: Thomas Daubney <thomas.daubney@arm.com>
Rewrite mbedtls_debug_print_mpi to be simpler and smaller. Leverage
mbedtls_mpi_bitlen() instead of manually looking for the leading
zeros.
Fix#4608: the old code made an invalid memory dereference when
X->n==0 (freshly initialized bignum with the value 0).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
TLS used to prefer larger curves, under the idea that a larger curve has a
higher security strength and is therefore harder to attack. However, brute
force attacks are not a practical concern, so this was not particularly
meaningful. If a curve is considered secure enough to be allowed, then we
might as well use it.
So order curves by resource usage. The exact definition of what this means
is purposefully left open. It may include criteria such as performance and
memory usage. Risk of side channels could be a factor as well, although it
didn't affect the current choice.
The current list happens to exactly correspond to the numbers reported by
one run of the benchmark program for "full handshake/s" on my machine.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
MBEDTLS_ECP_WINDOW_SIZE is a compromise between memory usage (growing based
on the value) and performance (faster with larger values). There are
disminishing returns as the value grows larger. Based on Manuel's benchmarks
recorded in https://github.com/ARMmbed/mbedtls/issues/4127, 4 is a good
compromise point, with larger values bringing little advantage. So reduce
the default from 6 to 4.
Document the default value as in optimized for performance mostly, but don't
document the specific value, so we may change it later or make it
platform-dependent.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This makes it easier to ensure that crypto_spe.h is included everywhere it
needs to be, and that it's included early enough to do its job (it must be
included before any mention of psa_xxx() functions with external linkage,
because it defines macros to rename these functions).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Merge part of the RSA entries into this one, as I think it's easier for
users to have all similar changes in one place regardless of whether
they were introduce in the same PR or not.
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
Add two functions mbedtls_dhm_get_len() and mbedtls_dhm_get_bitlen() to
query the length of the modulus in bytes or bits.
Remove the len field: the cost of calling mbedtls_dhm_get_len() each time
it's needed is negligible, and this improves the abstraction of the DHM
module.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Mbed OS now provides POSIX-like time functions, although not alarm() nor
signal(). It is possible to implement MBEDTLS_TIMING_ALT on Mbed OS, so
we should not artificially prevent this in check-config. Remove the the
check that prevents implementing MBEDTLS_TIMING_ALT on Mbed OS.
Note that this limitation originally was added in the following commit,
although there isn't much context around why the restriction was
imposed: 63e7ebaaa1 ("Add material for generating yotta module"). In
2015, Mbed OS was quite a different thing: no RTOS, no threads, just an
asynchronous event loop model. I'd suppose the asynchronous event loop
model made it difficult before to implement MBEDTLS_TIMING_C on Mbed OS,
but that is no longer the case.
Fixes#4633
Signed-off-by: Jaeden Amero <jaeden.amero@arm.com>
This change enables automatic detection and consumption of Mbed TLS
library targets from within other CMake projects. By generating an
`MbedTLSConfig.cmake` file, consuming projects receive a more complete
view of these targets, allowing them to be used as dependencies which
properly inherit the transitive dependencies of the libraries.
This is fairly fragile, as it seems Mbed TLS's libraries do not appear
to properly model their dependencies on other targets, including
third-party dependencies. It is, however, sufficient for building and
linking the compiled Mbed TLS libraries when there are no third-party
dependencies involved. Further work is needed for more complex
use-cases, but this will likely meet the needs of most projects.
Resolves#298. Probably useful for #2857.
Signed-off-by: Chris Kay <chris.kay@arm.com>
Calling mbedtls_mpi_cmp_int reveals the number of leading zero limbs
to an adversary who is capable of very fine-grained timing
measurements. This is very little information, but could be practical
with secp521r1 (1/512 chance of the leading limb being 0) if the
adversary can measure the precise timing of a large number of
signature operations.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
- Removing MBEDTLS_SSL_RECORD_CHECKING has nothing to do with TLS 1.0,
TLS 1.1 and DTLS 1.0. It has been included here as a consequence of an
unfortunate typo in the description of 4286. Actually, this macro was
removed independently and we already have a ChangeLog entry about it:
ChangeLog.d/issue4361.txt
- While at it, remove the word "deprecated": these macros and functions
had not been documented as deprecated in any version of the library
before being removed.
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
This commit fixes typos and re-words
the migration guide. It also adds
the issue number to the ChangeLog.
Signed-off-by: Thomas Daubney <thomas.daubney@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>
Conflicts:
library/version_features.c
programs/test/query_config.c
Files were removed in development branch and modified by current branch.
Conflicts fixes by removing them.
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>
Fix a pointer mismatch when int32_t is not int, for example on Cortex-M where
in32_t is long int. Fix#4530
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
The output parameter of mbedtls_sha256_finish_ret and mbedtls_sha256_ret
now has a pointer type rather than array type. This removes spurious
warnings in some compilers when outputting a SHA-224 hash into a
28-byte buffer.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
The output parameter of mbedtls_sha512_finish_ret and mbedtls_sha512_ret
now has a pointer type rather than array type. This removes spurious
warnings in some compilers when outputting a SHA-384 hash into a
48-byte buffer.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Building the library without entropy sources negates any and all security
provided by the library.
This option was originally requested a relatively long time ago and it
does not provide any tangible benefit for users any more.
Signed-off-by: Mateusz Starzyk <mateusz.starzyk@mobica.com>
The sample program aescrypt2 shows bad practice: hand-rolled CBC
implementation, CBC+HMAC for AEAD, hand-rolled iterated SHA-2 for key
stretching, no algorithm agility. The new sample program pbcrypt does
the same thing, but better. So remove aescrypt2.
Fix#1906
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Add implementation for MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS
Merging as it has been ready for four days now and I prefer not having to go through other rebases especially given the coming change of scope of development (3.0 rather than 2.2x).
The GCM interface now has separate functions to start the operation
and to pass the associated data.
This is in preparation for allowing the associated data to be passed
in chunks with repeatated calls to mbedtls_gcm_update_ad().
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Alternative implementations of GCM may delay the output of partial
blocks from mbedtls_gcm_update(). Add an output length parameter to
mbedtls_gcm_update() to allow such implementations to delay the output
of partial blocks. With the software implementation, there is no such
delay.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Alternative implementations of GCM may delay the output of partial
blocks from mbedtls_gcm_update(). Add an output parameter to
mbedtls_gcm_finish() to allow such implementations to pass the final
partial block back to the caller. With the software implementation,
this final output is always empty.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This reverts commit 0961e3db49.
This was merged by mistake in development instead of development_3.0.
Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
An incorrect error code addition was spotted by the new invasive testing
infrastructure whereby pk_get_pk_alg will always return a high level
error or zero and pk_parse_key_pkcs8_unencrypted_der will try to add
another high level error, resulting in a garbage error code.
Apply the same fix from ae3741e8a to fix the bug.
Signed-off-by: Chris Jones <christopher.jones@arm.com>
In a TLS client, enforce the Diffie-Hellman minimum parameter size
set with mbedtls_ssl_conf_dhm_min_bitlen() precisely. Before, the
minimum size was rounded down to the nearest multiple of 8.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Files available for use by alt implementations have been moved and renamed
so alt implementators should be told about the changes specific to them.
Signed-off-by: Chris Jones <christopher.jones@arm.com>
Reword the changelog entry to tailor it for users of the library as
opposed to developers of the library.
Signed-off-by: Chris Jones <christopher.jones@arm.com>
Memsan build was reporting a false positive use of uninitialised memory
in x509_crt.c on a struct filled by an _stat function call. According to
the man pages, the element reported has to be filled in by the call, so
to be safe, and keep memsan happy, zero the struct first.
Signed-off-by: Paul Elliott <paul.elliott@arm.com>
Fix function mbedtls_ecp_mul_shortcuts() to skip multiplication when m
is 0 and simply assignt 0 to R. Additionally fix ecjpake_zkp_read() to
return MBEDTLS_ERR_ECP_INVALID_KEY when the above condintion is met.
Fix#1792
Signed-off-by: TRodziewicz <rodziewicz@gmail.com>
Fix a stack buffer overflow with mbedtls_net_poll() and
mbedtls_net_recv_timeout() when given a file descriptor that is beyond
FD_SETSIZE. The bug was due to not checking that the file descriptor
is within the range of an fd_set object.
Fix#4169
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Although the library documentation does not guarantee that calling
mbedtls_entropy_free() twice works, it's a plausible assumption and it's
natural to write code that frees an object twice. While this is uncommon for
an entropy context, which is usually a global variable, it came up in our
own unit tests (random_twice tests in test_suite_random).
Announce this in the same changelog entry as for RSA because it's the same
bug in the two modules.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This brings them in line with PSA Crypto API 1.0.0
PSA_ALG_AEAD_WITH_DEFAULT_TAG_LENGTH -> PSA_ALG_AEAD_WITH_DEFAULT_LENGTH_TAG
PSA_ALG_AEAD_WITH_TAG_LENGTH -> PSA_ALG_AEAD_WITH_SHORTENED_TAG
Signed-off-by: Bence Szépkúti <bence.szepkuti@arm.com>
In psa_generate_derived_key_internal() an error case was returning
directly rather than jumping to the exit label, which meant that an
allocated buffer would not be free'd.
Found via coverity.
Signed-off-by: Paul Elliott <paul.elliott@arm.com>
Attempting to create an ECC key with a curve specification that is not
valid can plausibly fail with PSA_ERROR_INVALID_ARGUMENT ("this is not
a curve specification at all") or PSA_ERROR_NOT_SUPPORTED ("this may
be a curve specification, but not one I support"). The choice of error
is somewhat subjective.
Before this commit, due to happenstance in the implementation, an
attempt to use a curve that is declared in the PSA API but not
implemented in Mbed TLS returned PSA_ERROR_INVALID_ARGUMENT, whereas
an attempt to use a curve that Mbed TLS supports but for which support
was disabled at compile-time returned PSA_ERROR_NOT_SUPPORTED. This
inconsistency made it difficult to write negative tests that could
work whether the curve is implemented via Mbed TLS code or via a
driver.
After this commit, any attempt to use parameters that are not
recognized fails with NOT_SUPPORTED, whether a curve with the
specified size might plausibly exist or not, because "might plausibly
exist" is not something Mbed TLS can determine.
To keep returning INVALID_ARGUMENT when importing an ECC key with an
explicit "bits" attribute that is inconsistent with the size of the
key material, this commit changes the way mbedtls_ecc_group_of_psa()
works: it now works on a size in bits rather than bytes, with an extra
flag indicating whether the bit-size must be exact or not.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Fix a buffer overflow in mbedtls_mpi_sub_abs() when calculating
|A| - |B| where |B| is larger than |A| and has more limbs (so the
function should return MBEDTLS_ERR_MPI_NEGATIVE_VALUE).
Fix#4042
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
mbedtls_rsa_private() could return the sum of two RSA error codes
instead of a valid error code in some rare circumstances:
* If rsa_prepare_blinding() returned MBEDTLS_ERR_RSA_RNG_FAILED
(indicating a misbehaving or misconfigured RNG).
* If the comparison with the public value failed (typically indicating
a glitch attack).
Make sure not to add two high-level error codes.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Closing a wrapped key with the new SE driver interface while
MBEDTLS_PSA_CRYPTO_SE_C is also enabled leads to the key material not
being freed, even though an old SE driver is not in use, leading to a
memory leak. This is because a wrapped key is also considered external.
This commit extends the check for skipping by checking whether an
old-style SE driver is registered with the provided slot, in addition to
checking whether the key is external.
Signed-off-by: Fredrik Strupe <fredrik.strupe@silabs.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>
Extra whitespace and a missing newline at end of file was causing an error with
`check_files.py`.
Signed-off-by: Chris Jones <christopher.jones@arm.com>
* development: (488 commits)
Fix removal of deprecated PSA constants
Use GitHub-compatible table formatting
Remove psa header files in uninstall part
Change function casting in `ssl_calc_finished_tls_sha384`
Fix GCC warning in `ssl_calc_finished_tls_sha384`
Add changelog entry file to `ChangeLog.d`
Fix GCC warning in `ssl_calc_finished_tls_sha384`
Fix GCC warning about `test_snprintf`
Fix mismatched function parameters (prototype/definition)
Fix build failure on gcc-11
Copyediting
Clarifications around key import
Fix copypasta
A variable is unused in some configurations
Rename test_driver_keygen to test_driver_key_management
Move "internal use" sentence attached to the wrong function
Added changelog
Plug in the entry point for public key export through driver
tests: psa: Reset key attributes where needed
Improve/fix documentation
...
Add missing tag check for algorithm parameters when comparing the
signature in the description part of the cert against the actual
signature whilst loading a certificate. This was found by a
certificate (created by fuzzing) that openssl would not verify, but
mbedtls would.
Regression test added (one of the client certs modified accordingly)
Signed-off-by: Paul Elliott <paul.elliott@arm.com>
