The TinyCrypt PK signature wrapper uses ASN.1 writing functions
for length and tag, accounting for the only dependency of the
baremetal build on ASN.1 writing.
Since all lengths to be encoded are below 128 Bytes and are hence
ASN.1 encoded as single Bytes, the dependency on ASN.1 writing can
be removed at low complexity by writing the length and tags directly.
Previously, this wasn't necessary because ecdh.h was included
through ssl.h, but now that this is no longer the case (because
ssl.h doesn't use ECDH), we have to include it explicitly.
Previously, ecp.h was included only if MBEDTLS_ECDH_C was set,
which broke the build in configurations using ECDSA, but not ECDH.
An example of such a config is configs/config-thread.h, which
uses ECJPAKE exclusively.
Moreover, the inclusion of ecdh.h isn't needed, because the header
only uses constants defined in the ECP module.
Extend scope of TC in ECDH-param extraction from CRT
Previously, TinyCrypt was only used for ECDHE-ECDSA/RSA ciphersuites.
This commit is a step towards using it for _all_ ciphersuites involving
ECDHE (specifically: ECDHE, ECDHE-PSK, static ECDH), extending the scope
of the use of TinyCrypt in the writing of the ClientKeyExchange message.
Extend scope of TC in ECDH-param extraction from CRT
Previously, TinyCrypt was only used for ECDHE-ECDSA/RSA ciphersuites.
This commit is a step towards using it for _all_ ciphersuites involving
ECDHE (specifically: ECDHE, ECDHE-PSK, static ECDH), extending the scope
of the use of TinyCrypt in the parsing of the ServerKeyExchange message.
Previously, TinyCrypt was only used for ECDHE-ECDSA/RSA ciphersuites.
This commit is a step towards using it for _all_ ciphersuites involving
ECDHE (specifically: ECDHE, ECDHE-PSK, static ECDH), extending the scope
of the use of TinyCrypt in the parsing of the ClientKeyExchange message.
Previously, TinyCrypt was only used for ECDHE-ECDSA/RSA ciphersuites.
This commit is a step towards using it for _all_ ciphersuites involving
ECDHE (specifically: ECDHE, ECDHE-PSK, static ECDH), extending the scope
of the use of TinyCrypt in the writing of the ServerKeyExchange message.
Extend scope of TC in ECDH-param extraction from CRT
Previously, TinyCrypt was only used for ECDHE-ECDSA/RSA ciphersuites.
This commit is a step towards using it for _all_ ciphersuites involving
ECDHE (specifically: ECDHE, ECDHE-PSK, static ECDH), extending the scope
of the use of TinyCrypt in the assembly of the PMS.
Previously, the TinyCrypt component in all.sh restricted the ssl-opt.sh
to the 'Default, DTLS' test, due to implicit dependencies on Secp384r1.
These dependencies are now explicit and ssl-opt.sh skips corresponding
tests accordingly, so we can introduce a full run of ssl-opt.sh into
the TinyCrypt test in all.sh.
This commit modifies ssl-opt.sh to autodetect the use of test certificates
server5.* server6.* test-ca2.* using Secp384r1, and skips the corresponding
tests if MBEDTLS_ECP_DP_SECP384R1_ENABLED isn't set.
Previously, the TinyCrypt all.sh test restricted the run of compat.sh
to DTLS 1.2 and listed a few explicit ciphersuites.
This commit widens the scope of the test by testing any ciphersuite
based on ECDHE-ECDSA, regardless of TLS/DTLS or the particular version.
Further, it doesn't exclude SHA-384 as done previously.
This commit uses the flexibility of being able to chose CRTs and keys
to be used by compat.sh through predefined environment variables to
force the use of Secp256r1 certificates and keys in the all.sh test
for TinyCrypt.
This commit introduces environment variables
- SRV_ECDSA_CRT
- SRV_ECDSA_KEY
- CLI_ECDSA_CRT
- CLI_ECDSA_KEY
- SRV_RSA_CRT
- SRV_RSA_KEY
- CLI_RSA_CRT
- CLI_RSA_KEY
- CA_FILE
to tests/compat.sh which hold the path of the CA, client and server
certificate and key files to use by the script.
This is a preparatory step towards switching to a different set of
certificates and keys in case the configuration doesn't match the
certificates in use so far (e.g.: the ECDSA certificates use Secp384r1,
so if that's disabled, ECDSA tests will fail).
There is no apparent direct dependency, and the indirect dependency
through the RSA and legacy ECP modules is already encoded in the
chain
MBEDTLS_X509_USE_C
-> MBEDTLS_PK_PARSE_C
-> MBEDTLS_PK_C
-> MBEDTLS_RSA_C || MBEDTLS_ECP_C
-> MBEDTLS_BIGNUM_C
which will be modified to
MBEDTLS_X509_USE_C
-> MBEDTLS_PK_PARSE_C
-> MBEDTLS_PK_C
-> MBEDTLS_RSA_C || MBEDTLS_ECP_C || MBEDTLS_USE_TINYCRYPT
in which case MBEDTLS_BIGNUM_C is not needed for MBEDTLS_X509_USE_C
if only MBEDTLS_USE_TINYCRYPT is set, but not MBEDTLS_RSA_C or
MBEDTLS_ECP_C.
asn1.h uses uint8_t which is defined in stdint.h.
This wasn't caught earlier by the luck that whenever asn1.h
was included, another header was included earlier that did in
turn include stdint.h.
Remark: Including ecp.h is actually redundant because it's
also included from ecdh.h. However, it's good practice to
explicitly include header files that are being used directly,
and ssl.h does use MBEDTLS_ECP_MAX_BYTES which is defined in ecp.h.
ssl.h contains a dummy union of fields each large enough to
hold the PMS for a particular ciphersuite. In particular, for
pure-ECDH ciphersuites, it contains a field large enough to
hold the ECDH shared secret in any of the enabled curves.
So far, this upper bound was unconditionally chosen to be
MBEDTLS_ECP_MAX_BYTES from the ECP module.
With the introduction of TinyCrypt as an alternative implementation
for ECDH, we need to
- guard the use of MBEDTLS_ECP_MAX_BYTES because MBEDTLS_ECP_C
is no longer implied by the surrounding MBEDTLS_KEY_EXCHANGE_XXX
guards
- add another field which contains the maximum length of shared
ECDH secrets for curves supported by TinyCrypt.
mbedtls/ecp.h defines constants
MBEDTLS_ECP_PF_UNCOMPRESSED
MBEDTLS_ECP_PF_COMPRESSED
MBEDTLS_ECP_TLS_NAMED_CURVE
which regard the encoding of elliptic curves and curve point formats in TLS.
As such, they should be defined in the SSL namespace. Asides, this will help
replacing the legacy ECC crypto by alternative ECC implementations.
Even though exhaustive testing of TinyCrypt is left for later,
without this test we don't have any evidence that PK writing
works for TinyCrypt-based PK context.
TinyCrypt only supports Secp256r1, so skip all tests in test_suite_x509parse
which use different curves, while splitting those which rely on Secp256r1
alone into two tests: one for legacy ECC, and one for TinyCrypt.
Studying and improving the TinyCrypt test coverage is left for a later commit.
