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Add fast reduction for the other Koblitz curves

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Manuel Pégourié-Gonnard 2014-01-18 17:28:59 +01:00
parent 8887d8d37c
commit 9af7d3a35b
1 changed files with 90 additions and 31 deletions
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121
library/ecp_curves.c
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@ -653,6 +653,12 @@ static int ecp_mod_p521( mpi * );
#if defined(POLARSSL_ECP_DP_M255_ENABLED)
static int ecp_mod_p255( mpi * );
#endif
#if defined(POLARSSL_ECP_DP_SECP192K1_ENABLED)
static int ecp_mod_p192k1( mpi * );
#endif
#if defined(POLARSSL_ECP_DP_SECP224K1_ENABLED)
static int ecp_mod_p224k1( mpi * );
#endif
#if defined(POLARSSL_ECP_DP_SECP256K1_ENABLED)
static int ecp_mod_p256k1( mpi * );
#endif
@ -750,11 +756,13 @@ int ecp_use_known_dp( ecp_group *grp, ecp_group_id id )
#if defined(POLARSSL_ECP_DP_SECP192K1_ENABLED)
case POLARSSL_ECP_DP_SECP192K1:
grp->modp = ecp_mod_p192k1;
return( LOAD_GROUP_A( secp192k1 ) );
#endif /* POLARSSL_ECP_DP_SECP192K1_ENABLED */
#if defined(POLARSSL_ECP_DP_SECP224K1_ENABLED)
case POLARSSL_ECP_DP_SECP224K1:
grp->modp = ecp_mod_p224k1;
return( LOAD_GROUP_A( secp224k1 ) );
#endif /* POLARSSL_ECP_DP_SECP224K1_ENABLED */
@ -1238,53 +1246,52 @@ cleanup:
}
#endif /* POLARSSL_ECP_DP_M255_ENABLED */
#if defined(POLARSSL_ECP_DP_SECP256K1_ENABLED)
/* Size of p256k1 in terms of t_uint */
#define P256K1_WIDTH ( 256 / 8 / sizeof( t_uint ) )
/* Value of R (see below) */
static t_uint p256k1_r_p[] = {
BYTES_TO_T_UINT_8( 0xD1, 0x03, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00 ),
};
#define P256K1_R_WIDTH ( sizeof( p256k1_r_p ) / sizeof( t_uint ) )
#if defined(POLARSSL_ECP_DP_SECP192K1_ENABLED) || \
defined(POLARSSL_ECP_DP_SECP224K1_ENABLED) || \
defined(POLARSSL_ECP_DP_SECP256K1_ENABLED)
/*
* Fast quasi-reduction modulo p256k1 = 2^256 - R,
* with R = 2^32 + 2^9 + 2^8 + 2^7 + 2^6 + 2^4 + 1 = 4294968273
* Fast quasi-reduction modulo P = 2^s - R,
* with R about 33 bits, used by the Koblitz curves.
*
* Write N as A0 + 2^256 A1, return A0 + R * A1.
* Write N as A0 + 2^224 A1, return A0 + R * A1.
* Actually do two passes, since R is big.
*/
static int ecp_mod_p256k1( mpi *N )
#define P_KOBLITZ_MAX ( 256 / 8 / sizeof( t_uint ) ) // Max limbs in P
#define P_KOBLITZ_R ( 8 / sizeof( t_uint ) ) // Limbs in R
static inline int ecp_mod_koblitz( mpi *N, t_uint *Rp, size_t p_limbs,
size_t adjust, size_t shift, t_uint mask )
{
int ret;
size_t i;
mpi M, R;
t_uint Mp[P256K1_WIDTH + P256K1_R_WIDTH];
t_uint Mp[P_KOBLITZ_MAX + P_KOBLITZ_R];
if( N->n < P256K1_WIDTH )
if( N->n < p_limbs )
return( 0 );
/* Init R */
R.s = 1;
R.p = p256k1_r_p;
R.n = P256K1_R_WIDTH;
R.p = Rp;
R.n = P_KOBLITZ_R;
/* Common setup for M */
M.s = 1;
M.p = Mp;
/* M = A1 */
M.n = N->n - P256K1_WIDTH;
if( M.n > P256K1_WIDTH )
M.n = P256K1_WIDTH;
M.n = N->n - ( p_limbs - adjust );
if( M.n > p_limbs + adjust )
M.n = p_limbs + adjust;
memset( Mp, 0, sizeof Mp );
memcpy( Mp, N->p + P256K1_WIDTH, M.n * sizeof( t_uint ) );
M.n += R.n; /* Make room for multiplication by R */
memcpy( Mp, N->p + p_limbs - adjust, M.n * sizeof( t_uint ) );
if (shift != 0 )
MPI_CHK( mpi_shift_r( &M, shift ) );
M.n += R.n - adjust; /* Make room for multiplication by R */
/* N = A0 */
for( i = P256K1_WIDTH; i < N->n; i++ )
if (mask != 0 )
N->p[p_limbs - 1] &= mask;
for( i = p_limbs; i < N->n; i++ )
N->p[i] = 0;
/* N = A0 + R * A1 */
@ -1294,15 +1301,19 @@ static int ecp_mod_p256k1( mpi *N )
/* Second pass */
/* M = A1 */
M.n = N->n - P256K1_WIDTH;
if( M.n > P256K1_WIDTH )
M.n = P256K1_WIDTH;
M.n = N->n - ( p_limbs - adjust );
if( M.n > p_limbs + adjust )
M.n = p_limbs + adjust;
memset( Mp, 0, sizeof Mp );
memcpy( Mp, N->p + P256K1_WIDTH, M.n * sizeof( t_uint ) );
M.n += R.n; /* Make room for multiplication by R */
memcpy( Mp, N->p + p_limbs - adjust, M.n * sizeof( t_uint ) );
if (shift != 0 )
MPI_CHK( mpi_shift_r( &M, shift ) );
M.n += R.n - adjust; /* Make room for multiplication by R */
/* N = A0 */
for( i = P256K1_WIDTH; i < N->n; i++ )
if (mask != 0 )
N->p[p_limbs - 1] &= mask;
for( i = p_limbs; i < N->n; i++ )
N->p[i] = 0;
/* N = A0 + R * A1 */
@ -1312,6 +1323,54 @@ static int ecp_mod_p256k1( mpi *N )
cleanup:
return( ret );
}
#endif /* POLARSSL_ECP_DP_SECP192K1_ENABLED) ||
POLARSSL_ECP_DP_SECP224K1_ENABLED) ||
POLARSSL_ECP_DP_SECP256K1_ENABLED) */
#if defined(POLARSSL_ECP_DP_SECP192K1_ENABLED)
/*
* Fast quasi-reduction modulo p192k1 = 2^192 - R,
* with R = 2^32 + 2^12 + 2^8 + 2^7 + 2^6 + 2^3 + 1 = 0x0100001119
*/
static int ecp_mod_p192k1( mpi *N )
{
static t_uint Rp[] = {
BYTES_TO_T_UINT_8( 0xC9, 0x11, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00 ) };
return( ecp_mod_koblitz( N, Rp, 192 / 8 / sizeof( t_uint ), 0, 0, 0 ) );
}
#endif /* POLARSSL_ECP_DP_SECP192K1_ENABLED */
#if defined(POLARSSL_ECP_DP_SECP224K1_ENABLED)
/*
* Fast quasi-reduction modulo p224k1 = 2^224 - R,
* with R = 2^32 + 2^12 + 2^11 + 2^9 + 2^7 + 2^4 + 2 + 1 = 0x0100001A93
*/
static int ecp_mod_p224k1( mpi *N )
{
static t_uint Rp[] = {
BYTES_TO_T_UINT_8( 0x93, 0x1A, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00 ) };
#if defined(POLARSSL_HAVE_INT64)
return( ecp_mod_koblitz( N, Rp, 4, 1, 32, 0xFFFFFFFF ) );
#else
return( ecp_mod_koblitz( N, Rp, 224 / 8 / sizeof( t_uint ), 0, 0, 0 ) );
#endif
}
#endif /* POLARSSL_ECP_DP_SECP224K1_ENABLED */
#if defined(POLARSSL_ECP_DP_SECP256K1_ENABLED)
/*
* Fast quasi-reduction modulo p256k1 = 2^256 - R,
* with R = 2^32 + 2^9 + 2^8 + 2^7 + 2^6 + 2^4 + 1 = 0x01000003D1
*/
static int ecp_mod_p256k1( mpi *N )
{
static t_uint Rp[] = {
BYTES_TO_T_UINT_8( 0xD1, 0x03, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00 ) };
return( ecp_mod_koblitz( N, Rp, 256 / 8 / sizeof( t_uint ), 0, 0, 0 ) );
}
#endif /* POLARSSL_ECP_DP_SECP256K1_ENABLED */
#endif