As the optional RSA parameters DP, DQ and QP are effectively discarded (they are only considered for their length to
ensure that the key fills the entire buffer), it is not necessary to read them into separate MPI's.
The test case parses an RSA private key with N=P=Q=D=E=1 and expects a failure from the PK layer. With the weakened
semantics of `mbedtls_rsa_complete`, the latter won't throw an error on that key in case if MBEDTLS_RSA_NO_CRT is
set. This commit modifies the test case to use N=2 which is rejected by `mbedtls_rsa_complete` regardless of whether
MBEDTLS_RSA_NO_CRT is set or not.
The number of loop iterations per candidate in `mbedtls_deduce_primes` was off
by one. This commit corrects this and removes a toy non-example from the RSA
test suite, as it seems difficult to have the function fail on small values of N
even if D,E are corrupted.
This commit splits off the RSA helper functions into separate headers and
compilation units to have a clearer separation of the public RSA interface,
intended to be used by end-users, and the helper functions which are publicly
provided only for the benefit of designers of alternative RSA implementations.
The tests now accept two result parameters, one for the expected result of the
completion call, and one for the expected result of the subsequent sanity
check.
It is not necessary to pass a CSPRNG to `mbedtls_rsa_deduce_moduli`, as there
exist well-working static strategies, and even if a PRNG is preferred, a
non-secure one would be sufficient.
Further, the implementation is changed to use a static strategy for the choice
of candidates which according to some benchmarks even performs better than the
previous one using random candidate choices.
Original intention was to be allowed to perform in-place operations like changing the byte-order before importing
parameters into an HSM. Now a copy is needed in this case, but there's no more danger of a user expecting the arguments
to be left untouched.
Document explicitly that `mbedtls_rsa_check_privkey` and `mbedtls_rsa_complete` succeeding does not guarantee the
consistency of the underlying RSA private key but only that enough information is present to perform a private key
operation.
This commit adds a flag to the RSA import/export tests indicating whether it is
expected that a full RSA keypair can be set up from the provided parameters.
Further, the tests of `mbedtls_rsa_import` and `mbedtls_rsa_import_raw` are
expanded to perform key checks and an example encryption-decryption.
