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Add unit tests for fix_negative

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Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
This commit is contained in:
Gilles Peskine
2021-04-03 21:47:53 +02:00
parent 80ba850e27
commit 618be2ec41
4 changed files with 182 additions and 2 deletions
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7
library/ecp_curves.c
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@@ -25,6 +25,8 @@
#include "mbedtls/platform_util.h"
#include "mbedtls/error.h"
#include "ecp_invasive.h"
#include <string.h>
#if !defined(MBEDTLS_ECP_ALT)
@@ -1028,13 +1030,14 @@ static inline void sub32( uint32_t *dst, uint32_t src, signed char *carry )
STORE32; i++; \
cur = c > 0 ? c : 0; STORE32; \
cur = 0; while( ++i < MAX32 ) { STORE32; } \
if( c < 0 ) fix_negative( N, c, bits );
if( c < 0 ) mbedtls_ecp_fix_negative( N, c, bits );
/*
* If the result is negative, we get it in the form
* c * 2^(bits + 32) + N, with c negative and N positive shorter than 'bits'
*/
static inline void fix_negative( mbedtls_mpi *N, signed char c, size_t bits )
MBEDTLS_STATIC_TESTABLE
void mbedtls_ecp_fix_negative( mbedtls_mpi *N, signed char c, size_t bits )
{
size_t i;

14
library/ecp_invasive.h
View File

@@ -31,6 +31,20 @@
#if defined(MBEDTLS_TEST_HOOKS) && defined(MBEDTLS_ECP_C)
#if defined(MBEDTLS_ECP_DP_SECP224R1_ENABLED) || \
defined(MBEDTLS_ECP_DP_SECP256R1_ENABLED) || \
defined(MBEDTLS_ECP_DP_SECP384R1_ENABLED)
/* Preconditions:
* - bits is a multiple of 64 or is 224
* - c is -1 or -2
* - 0 <= N < 2^bits
* - N has room for bits+64 bits
*
* Set N to c * 2^bits + N.
*/
void mbedtls_ecp_fix_negative( mbedtls_mpi *N, signed char c, size_t bits );
#endif
#endif /* MBEDTLS_TEST_HOOKS && MBEDTLS_ECP_C */
#endif /* MBEDTLS_ECP_INVASIVE_H */