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Merge pull request #6407 from minosgalanakis/minos/6017_add_montgomery_constant_squared

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Bignum: Added pre-calculation of Montgomery constants
This commit is contained in:
Gilles Peskine
2022-10-26 14:28:16 +02:00
committed by GitHub
parent 4f7feca0dc 37ca3a9acd
commit d4d080b41b
4 changed files with 137 additions and 0 deletions
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14
library/bignum_core.c
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@ -511,4 +511,18 @@ void mbedtls_mpi_core_montmul( mbedtls_mpi_uint *X,
mbedtls_ct_mpi_uint_cond_assign( AN_limbs, X, T, (unsigned char) ( carry ^ borrow ) );
}
int mbedtls_mpi_core_get_mont_r2_unsafe( mbedtls_mpi *X,
const mbedtls_mpi *N )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
MBEDTLS_MPI_CHK( mbedtls_mpi_lset( X, 1 ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_shift_l( X, N->n * 2 * biL ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_mod_mpi( X, X, N ) );
MBEDTLS_MPI_CHK( mbedtls_mpi_shrink( X, N->n ) );
cleanup:
return( ret );
}
#endif /* MBEDTLS_BIGNUM_C */

18
library/bignum_core.h
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@ -412,4 +412,22 @@ void mbedtls_mpi_core_montmul( mbedtls_mpi_uint *X,
const mbedtls_mpi_uint *N, size_t AN_limbs,
mbedtls_mpi_uint mm, mbedtls_mpi_uint *T );
/**
* \brief Calculate the square of the Montgomery constant. (Needed
* for conversion and operations in Montgomery form.)
*
* \param[out] X A pointer to the result of the calculation of
* the square of the Montgomery constant:
* 2^{2*n*biL} mod N.
* \param[in] N Little-endian presentation of the modulus, which must be odd.
*
* \return 0 if successful.
* \return #MBEDTLS_ERR_MPI_ALLOC_FAILED if there is not enough space
* to store the value of Montgomery constant squared.
* \return #MBEDTLS_ERR_MPI_DIVISION_BY_ZERO if \p N modulus is zero.
* \return #MBEDTLS_ERR_MPI_NEGATIVE_VALUE if \p N modulus is negative.
*/
int mbedtls_mpi_core_get_mont_r2_unsafe( mbedtls_mpi *X,
const mbedtls_mpi *N );
#endif /* MBEDTLS_BIGNUM_CORE_H */