Add quasi-reduction function for ecp
Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
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2 changed files with 50 additions and 0 deletions
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@ -79,6 +79,8 @@
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#include "bn_mul.h"
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#include "ecp_invasive.h"
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#include "ecp_internal.h"
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#include "bignum_core.h"
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#include <string.h>
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@ -1029,6 +1031,20 @@ cleanup:
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return ret;
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}
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int mbedtls_ecp_quasi_reduction(mbedtls_mpi_uint *X,
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const mbedtls_mpi_mod_modulus *N)
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{
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if (N->limbs == 0) {
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return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
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}
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mbedtls_mpi_uint c = mbedtls_mpi_core_sub(X, X, N->p, N->limbs);
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(void) mbedtls_mpi_core_add_if(X, N->p, N->limbs, (unsigned) c);
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return 0;
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}
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/*
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* Fast mod-p functions expect their argument to be in the 0..p^2 range.
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*
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34
library/ecp_internal.h
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34
library/ecp_internal.h
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@ -0,0 +1,34 @@
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/**
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* \file ecp_internal.h
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*
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* \brief Function declarations for internal functions of elliptic curve
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* point arithmetic.
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*/
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/**
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef MBEDTLS_ECP_INTERNAL_H
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#define MBEDTLS_ECP_INTERNAL_H
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#include "common.h"
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#include "mbedtls/bignum.h"
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#include "bignum_mod.h"
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int mbedtls_ecp_quasi_reduction(mbedtls_mpi_uint *X,
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const mbedtls_mpi_mod_modulus *N);
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#endif /* MBEDTLS_ECP_INTERNAL_H */
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