There is some commented out X.509 certificate writing code present in
rsa_genkey. It looks like it has been commented out since the beginning
of time. Let's remove it, since commented out code is not in good style.
These examples rely on the NET module, which we want to remove. In
theory we could remove just the dependency, but we decided to remove the
whole example because:
- They showcase some bad crypto: custom, undocumented protocol (not
obviously broken though, apart from authenticating only one side);
hard-coded limit of 512-bit size for the DH modulus (2048 is the
recommended minimum these days); direct use of the shared secret as a
key (instead of applying a KDF); encryption with ECB, custom
parameters and the client not having the ability to verify them.
- The programs use the DH API in the same way that TLS does, so they
have limited demonstration value.
- The programs only show finite-field DH, which is not used all that
much these days. What people want to see is mostly ECDH.
Additional changes to temporarily enable running tests:
ssl_srv.c and test_suite_ecdh use mbedtls_ecp_group_load instead of
mbedtls_ecdh_setup
test_suite_ctr_drbg uses mbedtls_ctr_drbg_update instead of
mbedtls_ctr_drbg_update_ret
The previous prototype gave warnings are the strings produced by #cond and
__FILE__ are const, so we shouldn't implicitly cast them to non-const.
While at it modifying most example programs:
- include the header that has the function declaration, so that the definition
can be checked to match by the compiler
- fix whitespace
- make it work even if PLATFORM_C is not defined:
- CHECK_PARAMS is not documented as depending on PLATFORM_C and there is
no reason why it should
- so, remove the corresponding #if defined in each program...
- and add missing #defines for mbedtls_exit when needed
The result has been tested (make all test with -Werror) with the following
configurations:
- full with CHECK_PARAMS with PLATFORM_C
- full with CHECK_PARAMS without PLATFORM_C
- full without CHECK_PARAMS without PLATFORM_C
- full without CHECK_PARAMS with PLATFORM_C
Additionally, it has been manually tested that adding
mbedtls_aes_init( NULL );
near the normal call to mbedtls_aes_init() in programs/aes/aescrypt2.c has the
expected effect when running the program.
The sample programs require an additional handler function of
mbedtls_param_failed() to handle any failed parameter validation checks enabled
by the MBEDTLS_CHECK_PARAMS config.h option.
Some sample programs access structure fields directly. Making these work is
desirable in the long term, but these are not essential for the core
functionality in non-legacy mode.
When using a primality testing function the tolerable error rate depends
on the scheme in question, the required security strength and wether it
is used for key generation or parameter validation. To support all use
cases we need more flexibility than what the old API provides.
