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another way to mitigate timing attack

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This commit is contained in:
NIIBE Yutaka
2013-10-06 09:28:58 +09:00
parent 533ac62846
commit 84c25e5767
3 changed files with 83 additions and 8 deletions
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70
polarssl/library/bignum.c
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@@ -1326,6 +1326,72 @@ int mpi_mod_int( t_uint *r, const mpi *A, t_sint b )
return( 0 );
}
static void mpi_mul_hlp_mm ( size_t i, t_uint *s, t_uint *d, t_uint b)
{
t_uint c = 0;
#if defined(MULADDC_1024_LOOP)
MULADDC_1024_LOOP
for( ; i > 0; i-- )
{
MULADDC_INIT
MULADDC_CORE
MULADDC_STOP
}
#elif defined(MULADDC_HUIT)
for( ; i >= 8; i -= 8 )
{
MULADDC_INIT
MULADDC_HUIT
MULADDC_STOP
}
for( ; i > 0; i-- )
{
MULADDC_INIT
MULADDC_CORE
MULADDC_STOP
}
#else
for( ; i >= 16; i -= 16 )
{
MULADDC_INIT
MULADDC_CORE MULADDC_CORE
MULADDC_CORE MULADDC_CORE
MULADDC_CORE MULADDC_CORE
MULADDC_CORE MULADDC_CORE
MULADDC_CORE MULADDC_CORE
MULADDC_CORE MULADDC_CORE
MULADDC_CORE MULADDC_CORE
MULADDC_CORE MULADDC_CORE
MULADDC_STOP
}
for( ; i >= 8; i -= 8 )
{
MULADDC_INIT
MULADDC_CORE MULADDC_CORE
MULADDC_CORE MULADDC_CORE
MULADDC_CORE MULADDC_CORE
MULADDC_CORE MULADDC_CORE
MULADDC_STOP
}
for( ; i > 0; i-- )
{
MULADDC_INIT
MULADDC_CORE
MULADDC_STOP
}
#endif
*d += c; c = ( *d < c ); d++;
*d += c;
}
/*
* Fast Montgomery initialization (thanks to Tom St Denis)
*/
@@ -1366,8 +1432,8 @@ static void mpi_montmul( mpi *A, const mpi *B, const mpi *N, t_uint mm, const mp
u0 = A->p[i];
u1 = ( d[0] + u0 * B->p[0] ) * mm;
mpi_mul_hlp( m, B->p, d, u0 );
mpi_mul_hlp( n, N->p, d, u1 );
mpi_mul_hlp_mm( m, B->p, d, u0);
mpi_mul_hlp_mm( n, N->p, d, u1);
*d++ = u0; d[n + 1] = 0;
}