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ecp_curves: Switched to dynamic memory for

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Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>
This commit is contained in:
Minos Galanakis 2023-05-17 18:18:13 +01:00
parent 2daa374ea8
commit 65c386ee3d
1 changed files with 11 additions and 7 deletions
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18
library/ecp_curves.c
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@ -22,6 +22,7 @@
#if defined(MBEDTLS_ECP_LIGHT)
#include "mbedtls/ecp.h"
#include "mbedtls/platform.h"
#include "mbedtls/platform_util.h"
#include "mbedtls/error.h"
@ -5430,8 +5431,10 @@ cleanup:
MBEDTLS_STATIC_TESTABLE
int mbedtls_ecp_mod_p255_raw(mbedtls_mpi_uint *X, size_t X_Limbs)
{
mbedtls_mpi_uint carry[P255_WIDTH];
memset(carry, 0, sizeof(mbedtls_mpi_uint) * P255_WIDTH);
mbedtls_mpi_uint *carry = mbedtls_calloc(P255_WIDTH, ciL);
if (carry == NULL) {
return MBEDTLS_ERR_ECP_ALLOC_FAILED;
}
/* Step 1: Reduction to P255_WIDTH limbs */
if (X_Limbs > P255_WIDTH) {
@ -5440,21 +5443,22 @@ int mbedtls_ecp_mod_p255_raw(mbedtls_mpi_uint *X, size_t X_Limbs)
const size_t A1_limbs = X_Limbs - P255_WIDTH;
/* X = A0 + 38 * A1, capture carry out */
carry[0] = mbedtls_mpi_core_mla(X, P255_WIDTH, A1, A1_limbs, 38);
*carry = mbedtls_mpi_core_mla(X, P255_WIDTH, A1, A1_limbs, 38);
/* Clear top part */
memset(A1, 0, sizeof(mbedtls_mpi_uint) * A1_limbs);
}
/* Step 2: Reduce to <p
* Split as A0 + 2^255*c, with c a scalar, and compute A0 + 19*c */
carry[0] <<= 1;
carry[0] += (X[P255_WIDTH - 1] >> (biL - 1));
carry[0] *= 19;
*carry <<= 1;
*carry += (X[P255_WIDTH - 1] >> (biL - 1));
*carry *= 19;
/* Clear top bit */
X[P255_WIDTH - 1] <<= 1; X[P255_WIDTH - 1] >>= 1;
(void) mbedtls_mpi_core_add(X, X, &carry[0], P255_WIDTH);
(void) mbedtls_mpi_core_add(X, X, carry, P255_WIDTH);
mbedtls_free(carry);
return 0;
}
#endif /* MBEDTLS_ECP_DP_CURVE25519_ENABLED */