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>
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>
Since mbedtls_mpi_random() is not specific to ECC code, move it from
the ECP module to the bignum module.
This increases the code size in builds without short Weierstrass
curves (including builds without ECC at all) that do not optimize out
unused functions.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Add test cases for mbedtls_mpi_sub_abs() where the second operand has
more limbs than the first operand (which, if the extra limbs are not
all zero, implies that the function returns
MBEDTLS_ERR_MPI_NEGATIVE_VALUE).
This exposes a buffer overflow (reported in #4042).
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Run all the addition and subtraction tests with the result aliased to
the first operand and with the result aliased to the second operand.
Before, only some of the aliasing possibilities were tested, for only
some of the functions, with only some inputs.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
Fixes an issue where configs that had `MBEDTLS_MPI_MAX_BITS` greater than 256
but smaller than the test that was running (792 bits) the test would fail
incorrectly.
Signed-off-by: Chris Jones <christopher.jones@arm.com>
Move dependancy on `MBEDTLS_MPI_MAX_BITS` to apply to the specific test cases
which will break when `MBEDTLS_MPI_MAX_BITS` is too small. This re-enables
previous tests that were turned off accidentally.
Signed-off-by: Chris Jones <christopher.jones@arm.com>
In two test cases, the exponentiation computation was not being fully tested
as when A_bytes (the base) == N_bytes (the modulus) -> A = N. When this is the
case A is reduced to 0 and therefore the result of the computation will always
be 0.
This fixes that issue and therefore increases the test coverage to ensure
different computations are actually being run.
Signed-off-by: Chris Jones <christopher.jones@arm.com>
Reword test cases to be easier to read and understand.
Adds comments to better explain what the test is doing.
Signed-off-by: Chris Jones <christopher.jones@arm.com>
Add two further boundary tests for cases where both the exponent and modulus to
`mbedtls_mpi_exp_mod()` are `MBEDTLS_MPI_MAX_SIZE`, or longer, bytes long.
Signed-off-by: Chris Jones <christopher.jones@arm.com>
Adds test cases to ensure that `mbedtls_mpi_exp_mod` will return an error with
an exponent or modulus that is greater than `MBEDTLS_MPI_MAX_SIZE` in size.
Adds test cases to ensure that Diffie-Hellman will fail to make a key pair
(using `mbedtls_dhm_make_public`) when the prime modulus is greater than
`MBEDTLS_MPI_MAX_SIZE` in size.
Signed-off-by: Chris Jones <christopher.jones@arm.com>
Add a test case to ensure `mbedtls_mpi_exp_mod` fails when using a key size
larger than MBEDTLS_MPI_MAX_SIZE.
Add a test case to ensure that Diffie-Hellman operations fail when using a key
size larger than MBEDTLS_MPI_MAX_SIZE.
Signed-off-by: Chris Jones <christopher.jones@arm.com>
Positive tests: test that the RNG has the expected size, given that we
know how many leading zeros it has because we know how the function
consumes bytes and when the test RNG produces null bytes.
Negative tests: test that if the RNG is willing to emit less than the
number of wanted bytes, the function fails.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
The corner case tests were designed for 32 and 64 bit limbs
independently and performed only on the target platform. On the other
platform they are not corner cases anymore, but we can still exercise
them.
The corner case tests were designed for 64 bit limbs and failed on 32
bit platforms because the numbers in the test ended up being stored in a
different number of limbs and the function (correctly) returnd an error
upon receiving them.
The signature of mbedtls_mpi_cmp_mpi_ct() meant to support using it in
place of mbedtls_mpi_cmp_mpi(). This meant full comparison functionality
and a signed result.
To make the function more universal and friendly to constant time
coding, we change the result type to unsigned. Theoretically, we could
encode the comparison result in an unsigned value, but it would be less
intuitive.
Therefore we won't be able to represent the result as unsigned anymore
and the functionality will be constrained to checking if the first
operand is less than the second. This is sufficient to support the
current use case and to check any relationship between MPIs.
The only drawback is that we need to call the function twice when
checking for equality, but this can be optimised later if an when it is
needed.
Make check-test-cases.py pass.
Prior to this commit, there were many repeated test descriptions, but
none with the same test data and dependencies and comments, as checked
with the following command:
for x in tests/suites/*.data; do perl -00 -ne 'warn "$ARGV: $. = $seen{$_}\n" if $seen{$_}; $seen{$_}=$.' $x; done
Wherever a test suite contains multiple test cases with the exact same
description, add " [#1]", " [#2]", etc. to make the descriptions
unique. We don't currently use this particular arrangement of
punctuation, so all occurrences of " [#" were added by this script.
I used the following ad hoc code:
import sys
def fix_test_suite(data_file_name):
in_paragraph = False
total = {}
index = {}
lines = None
with open(data_file_name) as data_file:
lines = list(data_file.readlines())
for line in lines:
if line == '\n':
in_paragraph = False
continue
if line.startswith('#'):
continue
if not in_paragraph:
# This is a test case description line.
total[line] = total.get(line, 0) + 1
index[line] = 0
in_paragraph = True
with open(data_file_name, 'w') as data_file:
for line in lines:
if line in total and total[line] > 1:
index[line] += 1
line = '%s [#%d]\n' % (line[:-1], index[line])
data_file.write(line)
for data_file_name in sys.argv[1:]:
fix_test_suite(data_file_name)
The function `mbedtls_mpi_write_binary()` writes big endian byte order,
but we need to be able to write little endian in some caseses. (For
example when handling keys corresponding to Montgomery curves.)
Used `echo xx | tac -rs ..` to transform the test data to little endian.
The function `mbedtls_mpi_read_binary()` expects big endian byte order,
but we need to be able to read from little endian in some caseses. (For
example when handling keys corresponding to Montgomery curves.)
Used `echo xx | tac -rs .. | tr [a-z] [A-Z]` to transform the test data
to little endian and `echo "ibase=16;xx" | bc` to convert to decimal.
Extend the mbedtls_mpi_is_prime_det test to check that it reports
the number as prime when testing rounds-1 rounds, then reports the
number as composite when testing the full number of rounds.
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.
Primality tests have to deal with different distribution when generating
primes and when validating primes.
These new tests are testing if mbedtls_mpi_is_prime() is working
properly in the latter setting.
The new tests involve pseudoprimes with maximum number of
non-witnesses. The non-witnesses were generated by printing them
from mpi_miller_rabin(). The pseudoprimes were generated by the
following function:
void gen_monier( mbedtls_mpi* res, int nbits )
{
mbedtls_mpi p_2x_plus_1, p_4x_plus_1, x, tmp;
mbedtls_mpi_init( &p_2x_plus_1 );
mbedtls_mpi_init( &p_4x_plus_1 );
mbedtls_mpi_init( &x ); mbedtls_mpi_init( &tmp );
do
{
mbedtls_mpi_gen_prime( &p_2x_plus_1, nbits >> 1, 0,
rnd_std_rand, NULL );
mbedtls_mpi_sub_int( &x, &p_2x_plus_1, 1 );
mbedtls_mpi_div_int( &x, &tmp, &x, 2 );
if( mbedtls_mpi_get_bit( &x, 0 ) == 0 )
continue;
mbedtls_mpi_mul_int( &p_4x_plus_1, &x, 4 );
mbedtls_mpi_add_int( &p_4x_plus_1, &p_4x_plus_1, 1 );
if( mbedtls_mpi_is_prime( &p_4x_plus_1, rnd_std_rand,
NULL ) == 0 )
break;
} while( 1 );
mbedtls_mpi_mul_mpi( res, &p_2x_plus_1, &p_4x_plus_1 );
}
Setting the dh_flag to 1 used to indicate that the caller requests safe
primes from mbedtls_mpi_gen_prime. We generalize the functionality to
make room for more flags in that parameter.
- Separate string and hex parameter as unhexify is moved out of the function. It's input should only be hex.
- Fix test mbedtls_ccm_encrypt_and_tag that grows input message buffer with tag
- Add missing expected length parameter in ECP TLS tests
- Add deleted TEST_ASSERT and mbedtls calls that got removed in script based code generation
The specification requires that numbers are the raw entropy (except for odd/
even) and at least 2^(nbits-0.5). If not, new random bits need to be used for
the next number. Similarly, if the number is not prime new random bits need to
be used.
