Fix a bug introduced in "Fix multiplication producing a negative zero" that
caused the sign to be forced to +1 when A > 0, B < 0 and B's low-order limb
is 0.
Add a non-regression test. More generally, systematically test combinations
of leading zeros, trailing zeros and signs.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
No need to bypass the API to fill limbs. It's a better test to just
set the top bit that we want to have set, and it's one less bypass of
the API.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
In mbedtls_mpi_read_string, if the string is empty, return an empty bignum
rather than a bignum with one limb with the value 0.
Both representations are correct, so this is not, in principle, a
user-visible change. The change does leak however through
mbedtls_mpi_write_string in base 16 (but not in other bases), as it writes a
bignum with 0 limbs as "" but a bignum with the value 0 and at least one
limb as "00".
This change makes it possible to construct an empty bignum through
mbedtls_mpi_read_string, which is especially useful to construct test
cases (a common use of mbedtls_mpi_read_string, as most formats use in
production encode numbers in binary, to be read with mbedtls_mpi_read_binary
or mbedtls_mpi_read_binary_le).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Fix mbedtls_mpi_mul_mpi() when one of the operands is zero and the
other is negative. The sign of the result must be 1, since some
library functions do not treat {-1, 0, NULL} or {-1, n, {0}} as
representing the value 0.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Fix a null pointer dereference in mbedtls_mpi_exp_mod(X, A, N, E, _RR) when
A is the value 0 represented with 0 limbs.
Make the code a little more robust against similar bugs.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Test both 0 represented with 0 limbs ("0 (null)") and 0 represented
with 1 limb ("0 (1 limb)"), because occasionally there are bugs with
0-limb bignums and occasionally there are bugs with removing leading
zero limbs.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
mbedtls_mpi_exp_mod can be called in three ways regarding the speed-up
parameter _RR: null (unused), zero (will be updated), nonzero (will be
used). Systematically test all three.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Remove the RR parameter to the mbedtls_mpi_exp_mod test function.
It was never used in the test data, so there is no loss of functionality.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Test mbedtls_mpi_safe_cond_assign() and mbedtls_mpi_safe_cond_swap()
with their "unsafe" counterparts mbedtls_mpi_copy() and
mbedtls_mpi_swap(). This way we don't need to repeat the coverage of
test cases.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Similarly to "Overhaul testing of mbedtls_mpi_copy", simplify the code
to test mbedtls_mpi_swap to have just one function for distinct MPIs
and one function for swapping an MPI with itself, covering all cases
of size (0, 1, >1) and sign (>0, <0).
The test cases are exactly the same as for mbedtls_mpi_copy with the
following replacements:
* `Copy` -> `Swap`
* ` to ` -> ` with `
* `_copy` -> `_swap`
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Replace the two test functions mbedtls_mpi_copy_sint (supporting signed
inputs but always with exactly one limb) and mbedtls_mpi_copy_binary
(supporting arbitrary-sized inputs but not negative inputs) by a single
function that supports both arbitrary-sized inputs and arbitrary-signed
inputs. This will allows testing combinations like negative source and
zero-sized destination.
Also generalize mpi_copy_self to support arbitrary inputs.
Generate a new list of test cases systematically enumerating all
possibilities among various categories: zero with 0 or 1 limb, negative or
positive with 1 limb, negative or positive with >1 limb. I used the
following Perl script:
```
sub rhs { $_ = $_[0]; s/bead/beef/; s/ca5cadedb01dfaceacc01ade/face1e55ca11ab1ecab005e5/; $_ }
%v = (
"zero (null)" => "",
"zero (1 limb)" => "0",
"small positive" => "bead",
"large positive" => "ca5cadedb01dfaceacc01ade",
"small negative" => "-bead",
"large negative" => "-ca5cadedb01dfaceacc01ade",
);
foreach $s (sort keys %v) {
foreach $d (sort keys %v) {
printf "Copy %s to %s\nmbedtls_mpi_copy:\"%s\":\"%s\"\n\n",
$s, $d, $v{$s}, rhs($v{$d});
}
}
foreach $s (sort keys %v) {
printf "Copy self: %s\nmpi_copy_self:\"%s\"\n\n", $s, $v{$s};
}
```
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This is mostly to look for cases where the sign bit may have been left at 0
after zerozing memory, or a value of 0 with the sign bit set to -11. Both of
these mostly work fine, so they can go otherwise undetected by unit tests,
but they can break when certain combinations of functions are used.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Replace calls to mbedtls_mpi_read_string() with a wrapper
mbedtls_test_read_mpi() when reading test data except for the purpose
of testing mbedtls_mpi_read_string() itself. The wrapper lets the test
data control precisely how many limbs the constructed MPI has.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This test helper reads an MPI from a string and guarantees control over the
number of limbs of the MPI, allowing test cases to construct values with or
without leading zeros, including 0 with 0 limbs.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
in file tests/suite/test_suite_aes.function, aes_crypt_xts_size()
did not free the context upon the function exit.
The function now frees the context on exit.
Fixes#4176
Signed-off-by: JoeSubbiani <Joe.Subbiani@arm.com>
Add HKDF tests where the sequence of inputs differs from the nominal
case: missing step, duplicate step, step out of order, or invalid step.
There were already similar tests for TLS 1.2 PRF. Add one with a key
agreement which has slightly different code.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
There was already a test case for 0 but with a non-empty representation
(X->n == 1). Add a test case with X->n == 0 (freshly initialized mpi).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Do more iterations with small values. This makes it more likely that a
mistake on bounds will be detected.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Slightly simplify is_significantly_above_a_power_of_2() to make it
easier to understand:
* Remove the explicit negative answer for x <= 4. The only functional
difference this makes is that is_significantly_above_a_power_of_2(3)
is now true.
* Shift the most significant bit of x to position 8 rather than 15.
This makes the final comparison easier to explain.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Add unit tests for mbedtls_mpi_fill_random() and mbedtls_mpi_random()
when the resulting MPI object previously had a nonzero value. I wrote
those to catch a bug that I introduced during the development of
mbedtls_mpi_random() (but does not appear in a committed version).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
mbedtls_mpi_random() uses mbedtls_mpi_cmp_mpi_ct(), which requires its
two arguments to have the same storage size. This was not the case
when the upper bound passed to mbedtls_mpi_random() had leading zero
limbs.
Fix this by forcing the result MPI to the desired size. Since this is
not what mbedtls_mpi_fill_random() does, don't call it from
mbedtls_mpi_random(), but instead call a new auxiliary function.
Add tests to cover this and other conditions with varying sizes for
the two arguments.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
