Implement mbedtls_mpi_mod_sub()
Signed-off-by: Tom Cosgrove <tom.cosgrove@arm.com>
This commit is contained in:
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c3902ac661
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5 changed files with 218 additions and 1 deletions
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@ -179,7 +179,18 @@ exit:
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/* END MERGE SLOT 2 */
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/* END MERGE SLOT 2 */
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/* BEGIN MERGE SLOT 3 */
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/* BEGIN MERGE SLOT 3 */
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int mbedtls_mpi_mod_sub( mbedtls_mpi_mod_residue *X,
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const mbedtls_mpi_mod_residue *A,
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const mbedtls_mpi_mod_residue *B,
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const mbedtls_mpi_mod_modulus *N )
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{
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if( X->limbs != N->limbs || A->limbs != N->limbs || B->limbs != N->limbs )
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return( MBEDTLS_ERR_MPI_BAD_INPUT_DATA );
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mbedtls_mpi_mod_raw_sub( X->p, A->p, B->p, N );
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return( 0 );
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}
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/* END MERGE SLOT 3 */
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/* END MERGE SLOT 3 */
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/* BEGIN MERGE SLOT 4 */
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/* BEGIN MERGE SLOT 4 */
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@ -163,7 +163,35 @@ void mbedtls_mpi_mod_modulus_free( mbedtls_mpi_mod_modulus *m );
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/* END MERGE SLOT 2 */
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/* END MERGE SLOT 2 */
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/* BEGIN MERGE SLOT 3 */
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/* BEGIN MERGE SLOT 3 */
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/**
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* \brief Perform a fixed-size modular subtraction.
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*
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* Calculate `A - B modulo N`.
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*
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* \p A, \p B and \p X must all have the same number of limbs as \p N.
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*
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* \p X may be aliased to \p A or \p B, or even both, but may not overlap
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* either otherwise.
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*
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* \note This function does not check that \p A or \p B are in canonical
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* form (that is, are < \p N) - that will have been done by
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* mbedtls_mpi_mod_residue_setup().
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*
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* \param[out] X The address of the result MPI. Must be initialized.
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* Must have the same number of limbs as the modulus \p N.
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* \param[in] A The address of the first MPI.
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* \param[in] B The address of the second MPI.
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* \param[in] N The address of the modulus. Used to perform a modulo
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* operation on the result of the subtraction.
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*
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* \return \c 0 if successful.
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* \return #MBEDTLS_ERR_MPI_BAD_INPUT_DATA if the given MPIs do not
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* have the correct number of limbs.
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*/
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int mbedtls_mpi_mod_sub( mbedtls_mpi_mod_residue *X,
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const mbedtls_mpi_mod_residue *A,
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const mbedtls_mpi_mod_residue *B,
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const mbedtls_mpi_mod_modulus *N );
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/* END MERGE SLOT 3 */
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/* END MERGE SLOT 3 */
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/* BEGIN MERGE SLOT 4 */
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/* BEGIN MERGE SLOT 4 */
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@ -34,6 +34,25 @@ class BignumModTarget(test_data_generation.BaseTarget):
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# BEGIN MERGE SLOT 3
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# BEGIN MERGE SLOT 3
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class BignumModSub(bignum_common.ModOperationCommon, BignumModTarget):
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"""Test cases for bignum mpi_mod_sub()."""
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symbol = "-"
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test_function = "mpi_mod_sub"
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test_name = "mbedtls_mpi_mod_sub"
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input_style = "fixed"
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arity = 2
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# To make negative tests easier, append 0 for success to the generated cases
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def arguments(self) -> List[str]:
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return [bignum_common.quote_str(n) for n in [self.arg_n,
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self.arg_a,
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self.arg_b]
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] + self.result() + ["0"]
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def result(self) -> List[str]:
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result = (self.int_a - self.int_b) % self.int_n
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return [self.format_result(result)]
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# END MERGE SLOT 3
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# END MERGE SLOT 3
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# BEGIN MERGE SLOT 4
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# BEGIN MERGE SLOT 4
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@ -17,6 +17,27 @@ mpi_mod_setup:MBEDTLS_MPI_MOD_REP_MONTGOMERY:0
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# BEGIN MERGE SLOT 3
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# BEGIN MERGE SLOT 3
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mpi_mod_sub base case for negative testing (N, a, b all >= 1 limb)
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mpi_mod_sub:"014320a022ccb75bdf470ddf25":"000000025a55a46e5da99c71c7":"00033b2e3c9fd0803ce8000f93":"013fe57440828b4a0008aa4159":0
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mpi_mod_sub with modulus too long/both inputs too short
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mpi_mod_sub:"0000000014320a022ccb75bdf470ddf25":"000000025a55a46e5da99c71c7":"00033b2e3c9fd0803ce8000f93":"00":MBEDTLS_ERR_MPI_BAD_INPUT_DATA
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mpi_mod_sub with first input too long
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mpi_mod_sub:"014320a022ccb75bdf470ddf25":"0000000000000025a55a46e5da99c71c7":"00033b2e3c9fd0803ce8000f93":"00":MBEDTLS_ERR_MPI_BAD_INPUT_DATA
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mpi_mod_sub with second input too long
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mpi_mod_sub:"014320a022ccb75bdf470ddf25":"000000025a55a46e5da99c71c7":"000000000033b2e3c9fd0803ce8000f93":"00":MBEDTLS_ERR_MPI_BAD_INPUT_DATA
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mpi_mod_sub with both inputs too long
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mpi_mod_sub:"014320a022ccb75bdf470ddf25":"0000000000000025a55a46e5da99c71c7":"000000000033b2e3c9fd0803ce8000f93":"00":MBEDTLS_ERR_MPI_BAD_INPUT_DATA
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mpi_mod_sub with first input too short
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mpi_mod_sub:"014320a022ccb75bdf470ddf25":"a99c71c7":"00033b2e3c9fd0803ce8000f93":"00":MBEDTLS_ERR_MPI_BAD_INPUT_DATA
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mpi_mod_sub with second input too short
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mpi_mod_sub:"014320a022ccb75bdf470ddf25":"000000025a55a46e5da99c71c7":"e8000f93":"00":MBEDTLS_ERR_MPI_BAD_INPUT_DATA
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# END MERGE SLOT 3
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# END MERGE SLOT 3
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# BEGIN MERGE SLOT 4
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# BEGIN MERGE SLOT 4
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@ -4,6 +4,47 @@
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#include "bignum_mod.h"
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#include "bignum_mod.h"
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#include "constant_time_internal.h"
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#include "constant_time_internal.h"
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#include "test/constant_flow.h"
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#include "test/constant_flow.h"
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#define TEST_COMPARE_MPI_RESIDUES( a, b ) \
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ASSERT_COMPARE( (a).p, (a).limbs * sizeof(mbedtls_mpi_uint), \
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(b).p, (b).limbs * sizeof(mbedtls_mpi_uint) )
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int test_read_modulus( mbedtls_mpi_mod_modulus *m,
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mbedtls_mpi_mod_rep_selector int_rep,
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char *input )
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{
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mbedtls_mpi_uint *p = NULL;
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size_t limbs;
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int ret = mbedtls_test_read_mpi_core( &p, &limbs, input );
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if( ret != 0 )
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return( ret );
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return( mbedtls_mpi_mod_modulus_setup( m, p, limbs, int_rep ) );
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}
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int test_read_residue( mbedtls_mpi_mod_residue *r,
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const mbedtls_mpi_mod_modulus *m,
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char *input,
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int skip_limbs_and_value_checks )
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{
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mbedtls_mpi_uint *p = NULL;
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size_t limbs;
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int ret = mbedtls_test_read_mpi_core( &p, &limbs, input );
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if( ret != 0 )
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return( ret );
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if( skip_limbs_and_value_checks )
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{
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r->p = p;
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r->limbs = limbs;
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return( 0 );
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}
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/* mbedtls_mpi_mod_residue_setup() checks limbs, and that value < m */
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return( mbedtls_mpi_mod_residue_setup( r, m, p, limbs ) );
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}
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/* END_HEADER */
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/* END_HEADER */
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/* BEGIN_DEPENDENCIES
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/* BEGIN_DEPENDENCIES
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@ -64,7 +105,104 @@ exit:
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/* END MERGE SLOT 2 */
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/* END MERGE SLOT 2 */
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/* BEGIN MERGE SLOT 3 */
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/* BEGIN MERGE SLOT 3 */
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/* BEGIN_CASE */
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void mpi_mod_sub( char * input_N,
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char * input_A, char * input_B,
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char * input_D, int oret )
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{
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mbedtls_mpi_mod_residue a = { NULL, 0 };
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mbedtls_mpi_mod_residue b = { NULL, 0 };
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mbedtls_mpi_mod_residue d = { NULL, 0 };
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mbedtls_mpi_mod_residue x = { NULL, 0 };
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mbedtls_mpi_uint *X_raw = NULL;
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mbedtls_mpi_mod_modulus m;
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mbedtls_mpi_mod_modulus_init( &m );
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TEST_EQUAL( 0,
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test_read_modulus( &m, MBEDTLS_MPI_MOD_REP_MONTGOMERY, input_N ) );
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/* test_read_residue() normally checks that inputs have the same number of
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* limbs as the modulus. For negative testing we can ask it to skip this
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* with a non-zero final parameter. */
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TEST_EQUAL( 0, test_read_residue( &a, &m, input_A, oret != 0 ) );
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TEST_EQUAL( 0, test_read_residue( &b, &m, input_B, oret != 0 ) );
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TEST_EQUAL( 0, test_read_residue( &d, &m, input_D, oret != 0 ) );
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size_t limbs = m.limbs;
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size_t bytes = limbs * sizeof( *X_raw );
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/* One spare limb for negative testing */
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ASSERT_ALLOC( X_raw, limbs + 1 );
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if( oret == 0 )
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{
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/* Sneak in a couple of negative tests on known-good data */
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/* First, negative test with too many limbs in output */
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x.p = X_raw;
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x.limbs = limbs + 1;
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TEST_EQUAL( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
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mbedtls_mpi_mod_sub( &x, &a, &b, &m ) );
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/* Then negative test with too few limbs in output */
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if( limbs > 1 )
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{
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x.p = X_raw;
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x.limbs = limbs - 1;
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TEST_EQUAL( MBEDTLS_ERR_MPI_BAD_INPUT_DATA,
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mbedtls_mpi_mod_sub( &x, &a, &b, &m ) );
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}
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/* Negative testing with too many/too few limbs in a and b is covered by
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* manually-written test cases with oret != 0. */
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/* Back to the normally-scheduled programme */
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}
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TEST_EQUAL( 0, mbedtls_mpi_mod_residue_setup( &x, &m, X_raw, limbs ) );
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/* a - b => Correct result, or expected error */
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TEST_EQUAL( oret, mbedtls_mpi_mod_sub( &x, &a, &b, &m ) );
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if( oret != 0 )
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goto exit;
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TEST_COMPARE_MPI_RESIDUES( x, d );
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/* a - b: alias x to a => Correct result */
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memcpy( x.p, a.p, bytes );
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TEST_EQUAL( 0, mbedtls_mpi_mod_sub( &x, &x, &b, &m ) );
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TEST_COMPARE_MPI_RESIDUES( x, d );
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/* a - b: alias x to b => Correct result */
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memcpy( x.p, b.p, bytes );
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TEST_EQUAL( 0, mbedtls_mpi_mod_sub( &x, &a, &x, &m ) );
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TEST_COMPARE_MPI_RESIDUES( x, d );
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if ( memcmp( a.p, b.p, bytes ) == 0 )
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{
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/* a == b: alias a and b */
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/* a - a => Correct result */
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TEST_EQUAL( 0, mbedtls_mpi_mod_sub( &x, &a, &a, &m ) );
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TEST_COMPARE_MPI_RESIDUES( x, d );
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/* a - a: x, a, b all aliased together => Correct result */
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memcpy( x.p, a.p, bytes );
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TEST_EQUAL( 0, mbedtls_mpi_mod_sub( &x, &x, &x, &m ) );
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TEST_COMPARE_MPI_RESIDUES( x, d );
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}
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exit:
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mbedtls_free( (void *)m.p ); /* mbedtls_mpi_mod_modulus_free() sets m.p = NULL */
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mbedtls_mpi_mod_modulus_free( &m );
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mbedtls_free( a.p );
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mbedtls_free( b.p );
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mbedtls_free( d.p );
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mbedtls_free( X_raw );
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}
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/* END_CASE */
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/* END MERGE SLOT 3 */
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/* END MERGE SLOT 3 */
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/* BEGIN MERGE SLOT 4 */
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/* BEGIN MERGE SLOT 4 */
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