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https://github.com/Mbed-TLS/mbedtls.git
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79b70f6394
The unit tests were created by capturing runs of the existing function during execution of existing unit tests. Signed-off-by: Tom Cosgrove <tom.cosgrove@arm.com>
141 lines
3.7 KiB
C
141 lines
3.7 KiB
C
/*
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* Multi-precision integer library
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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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#include "common.h"
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#if defined(MBEDTLS_BIGNUM_C)
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#include "mbedtls/bignum.h"
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#include "bignum_core.h"
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#include "bn_mul.h"
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#include <string.h>
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void mbedtls_mpi_core_montmul( mbedtls_mpi_uint *X,
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const mbedtls_mpi_uint *A,
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const mbedtls_mpi_uint *B,
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size_t B_len,
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const mbedtls_mpi_uint *N,
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size_t n,
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mbedtls_mpi_uint mm,
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mbedtls_mpi_uint *T )
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{
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memset( T, 0, (2*n+1)*ciL );
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for( size_t i = 0; i < n; i++, T++ )
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{
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mbedtls_mpi_uint u0, u1;
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/* T = (T + u0*B + u1*N) / 2^biL */
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u0 = A[i];
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u1 = ( T[0] + u0 * B[0] ) * mm;
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(void) mbedtls_mpi_core_mla( T, n + 2, B, B_len, u0 );
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(void) mbedtls_mpi_core_mla( T, n + 2, N, n, u1 );
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}
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mbedtls_mpi_uint carry, borrow;
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carry = T[n];
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borrow = mbedtls_mpi_core_sub( X, T, N, n );
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(void) mbedtls_mpi_core_add_if( X, N, n, ( carry < borrow ) );
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}
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/*
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* Fast Montgomery initialization (thanks to Tom St Denis).
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*/
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mbedtls_mpi_uint mbedtls_mpi_montg_init( mbedtls_mpi_uint m0 )
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{
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mbedtls_mpi_uint x = m0;
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x += ( ( m0 + 2 ) & 4 ) << 1;
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for( unsigned int i = biL; i >= 8; i /= 2 )
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x *= ( 2 - ( m0 * x ) );
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return( ~x + 1 );
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}
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mbedtls_mpi_uint mbedtls_mpi_core_mla( mbedtls_mpi_uint *d, size_t d_len,
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const mbedtls_mpi_uint *s, size_t s_len,
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mbedtls_mpi_uint b )
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{
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mbedtls_mpi_uint c = 0; /* carry */
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if( d_len < s_len )
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s_len = d_len;
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size_t excess_len = d_len - s_len;
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size_t steps_x8 = s_len / 8;
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size_t steps_x1 = s_len & 7;
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while( steps_x8-- )
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{
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MULADDC_X8_INIT
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MULADDC_X8_CORE
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MULADDC_X8_STOP
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}
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while( steps_x1-- )
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{
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MULADDC_X1_INIT
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MULADDC_X1_CORE
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MULADDC_X1_STOP
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}
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while( excess_len-- )
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{
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*d += c; c = ( *d < c ); d++;
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}
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return( c );
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}
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mbedtls_mpi_uint mbedtls_mpi_core_sub( mbedtls_mpi_uint *d,
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const mbedtls_mpi_uint *l,
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const mbedtls_mpi_uint *r,
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size_t n )
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{
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mbedtls_mpi_uint c = 0, t, z;
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for( size_t i = 0; i < n; i++ )
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{
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z = ( l[i] < c ); t = l[i] - c;
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c = ( t < r[i] ) + z; d[i] = t - r[i];
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}
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return( c );
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}
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mbedtls_mpi_uint mbedtls_mpi_core_add_if( mbedtls_mpi_uint *d,
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const mbedtls_mpi_uint *r,
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size_t n,
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unsigned cond )
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{
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mbedtls_mpi_uint c = 0, t;
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for( size_t i = 0; i < n; i++ )
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{
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mbedtls_mpi_uint add = cond * r[i];
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t = c;
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t += d[i]; c = ( t < d[i] );
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t += add; c += ( t < add );
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d[i] = t;
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}
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return( c );
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}
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#endif /* MBEDTLS_BIGNUM_C */
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