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bignum: update API mbedtls_mpi_exp_mod_unsafe to support hardware implementation

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This commit is contained in:
nilesh.kale 2024-09-24 15:49:15 +05:30
parent b8e884f0bc
commit f635fed592
1 changed files with 17 additions and 2 deletions
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19
library/bignum.c
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@ -1613,6 +1613,14 @@ int mbedtls_mpi_mod_int(mbedtls_mpi_uint *r, const mbedtls_mpi *A, mbedtls_mpi_s
return 0;
}
/*
* MbedTLS has added new software API mbedtls_mpi_exp_mod_optionally_safe().
* This API handles RSA public operations in non-constant time manner (and hence efficient),
* but for the hardware MPI case, we fallback to the `mbedtls_mpi_exp_mod()` implementation itself
* and hence disabling it here.
*/
#if !defined(MBEDTLS_MPI_EXP_MOD_ALT)
/*
* Warning! If the parameter E_public has MBEDTLS_MPI_IS_PUBLIC as its value,
* this function is not constant time with respect to the exponent (parameter E).
@ -1731,8 +1739,6 @@ cleanup:
return ret;
}
#if !defined(MBEDTLS_MPI_EXP_MOD_ALT)
/*
* Sliding-window exponentiation: X = A^E mod N (HAC 14.85)
*/
@ -1754,7 +1760,16 @@ int mbedtls_mpi_exp_mod_unsafe(mbedtls_mpi *X, const mbedtls_mpi *A,
const mbedtls_mpi *E, const mbedtls_mpi *N,
mbedtls_mpi *prec_RR)
{
/*
* If hardware is enabled, we use MPI crypto layer implementation,
* else we use mbedtls implementation.
*/
#if defined(MBEDTLS_MPI_EXP_MOD_ALT)
return mbedtls_mpi_exp_mod(X, A, E, N, prec_RR);
#else
return mbedtls_mpi_exp_mod_optionally_safe(X, A, E, MBEDTLS_MPI_IS_PUBLIC, N, prec_RR);
#endif
}