We were still reusing the internal HMAC-DRBG of the deterministic ECDSA
for blinding. This meant that with cryptographically low likelyhood the
result was not the same signature as the one the deterministic ECDSA
algorithm has to produce (however it is still a valid ECDSA signature).
To correct this we seed a second HMAC-DRBG with the same seed to restore
correct behavior. We also apply a label to avoid reusing the bits of the
ephemeral key for a different purpose and reduce the chance that they
leak.
This workaround can't be implemented in the restartable case without
penalising the case where external RNG is available or completely
defeating the purpose of the restartable feature, therefore in this case
the small chance of incorrect behavior remains.
Alternative implementations are often hardware accelerators and might
not need an RNG for blinding. But if they do, then we make them misuse
the RNG in the deterministic case.
There are several way around this:
- Exposing a lower level function for replacement. This would be the
optimal solution, but litters the API and is not backward compatible.
- Introducing a new compile time option for replacing the deterministic
function. This would mostly cover the same code as
MBEDTLS_ECDSA_DETERMINISTIC and would be yet another compile time flag.
- Reusing the existing MBEDTLS_ECDSA_DETERMINISTIC macro. This changes
the algorithm used by the PK layer from deterministic to randomised if
the alternative implementation is present.
This commit implements the third option. This is a temporary solution
and should be fixed at the next device driver API change.
`mbedtls_ecdsa_sign_det` reuses the internal HMAC-DRBG instance to
implement blinding. The advantage of this is that the algorithm is
deterministic too, not just the resulting signature. The drawback is
that the blinding is always the same for the same key and message.
This diminishes the efficiency of blinding and leaks information about
the private key.
A function that takes external randomness fixes this weakness.
Wildcard patterns now work with command line COMPONENT arguments
without --except as well as with. You can now run e.g.
`all.sh "check_*` to run all the sanity checks.
After backing up and restoring config.h, `git diff-files` may report
it as potentially-changed because it isn't sure whether the index is
up to date. To avoid this, make sure that the git index is up-to-date.
This fixes the warning about changed config.h that you might get when
you run all.sh twice in succession, yet if you run `git status` or
`git diff` everything seems up to date and you no longer get the
warning because these git commands update the index.
https://stackoverflow.com/questions/36367190/git-diff-files-output-changes-after-git-status
Only look for armcc if component_build_armcc or component_build_yotta
is to be executed, instead of requiring the option --no-armcc.
You can still pass --no-armcc, but it's no longer required when
listing components to run. With no list of components or an exclude
list on the command line, --no-armcc is equivalent to having
build_armcc in the exclude list.
Omit the yotta pre-checks if the build_yotta component is not going to
be executed. This makes --no-yotta equivalent to specifying a list of
components to run that doesn't include build_yotta.
Add a conditional execution facility: if a function support_xxx exists
and returns false then component_xxx is not executed (except when the
command line lists an explicit set of components to execute).
Use this facility for the 64-bit-specific or amd64-specific components.
MAKEFLAGS was set to -j if it was already set, instead of being set if
not previously set as intended. So now all.sh will do parallel builds
if invoked without MAKEFLAGS in the environment.
Don't bail out of all.sh if the OS isn't Linux. We only expect
everything to pass on a recent Linux x86_64, but it's useful to call
all.sh to run some components on any platform.
In all.sh, always run both MemorySanitizer and Valgrind. Valgrind is
slower than ASan and MSan but finds some things that they don't.
Run MSan unconditionally, not just on Linux/x86_64. MSan is supported
on some other OSes and CPUs these days.
Use `all.sh --except test_memsan` if you want to omit MSan because it
isn't supported on your platform. Use `all.sh --except test_memcheck`
if you want to omit Valgrind because it's too slow.
Portability: ecognize amd64 (FreeBSD arch string) as well as x86_64
(Linux arch string) for `uname -m`. The `make` utility must still
be GNU make.
Use `cmake -D CMAKE_BUILD_TYPE=Asan` rather than manually setting
`-fsanitize=address`. This lets cmake determine the necessary compiler
and linker flags.
With UNSAFE_BUILD on, force -Wno-error. This is necessary to build
with MBEDTLS_TEST_NULL_ENTROPY.
In all.sh, always save config.h before running a component, instead of
doing it manually in each component that requires it (except when we
forget, which has happened). This would break a script that requires
config.h.bak not to exist, but we don't have any of those.
Split the long list of tests into individual functions. Each time the
test code called the `cleanup` function, I start a new function called
`component_xxx`.
Run all the components by enumerating the `component_xxx` functions.
After running each component, call `cleanup`.
A few sanity checks didn't have calls to `cleanup` because they didn't
need them. I put them into separate components anyway, so there are
now a few extra harmless calls to `cleanup`.
Move almost all the code of this script into functions. There is no
intended behavior change. The goal of this commit is to make
subsequent improvements easier to follow.
A very large number of lines have been reintended. To see what's going
on, ignore whitespace differences (e.g. diff -w).
I followed the following rules:
* Minimize the amount of code that gets moved.
* Don't change anything to what gets executed or displayed.
* Almost all the code must end up in a function.
This commit is in preparation for breaking up the sequence of tests
into individual components that can run independently.
tests/Makefile had some unused warnings disabled unnecessarily, which
test-ref-configs.pl was turning back on. We don't need to disable these warnings
so I'm turning them back on.
Dependent on configured options, not all of the helper functions were being
used, which was leading to warning of unused functions with Clang.
To avoid any complex compile time options, or adding more logic to
generate_test_code.py to screen out unused functions, those functions which were
provoking the warning were changed to remove static, remove them from file
scope, and expose them to the linker.
Since the AD too long is a limitation on Mbed TLS,
HW accelerators may support this. Run the test for AD too long,
only if `MBEDTLS_CCM_ALT` is not defined.
Addresses comment in #1996.
Return the error code if failed, instead of returning value `1`.
If not failed, return the call of the underlying function,
in `mbedtls_ecdsa_genkey()`.
