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Merge pull request #6971 from gabor-mezei-arm/6026_Secp192r1_fast_reduction

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Extract Secp192r1 fast reduction from the prototype
This commit is contained in:
Gilles Peskine
2023-02-15 16:22:36 +01:00
committed by GitHub
parent 6778ddf657 0b4b8e3c5e
commit e2a9f86755
9 changed files with 286 additions and 18 deletions
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55
library/ecp_curves.c
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@ -4570,6 +4570,8 @@ static int ecp_group_load(mbedtls_ecp_group *grp,
/* Forward declarations */
#if defined(MBEDTLS_ECP_DP_SECP192R1_ENABLED)
static int ecp_mod_p192(mbedtls_mpi *);
MBEDTLS_STATIC_TESTABLE
int mbedtls_ecp_mod_p192_raw(mbedtls_mpi_uint *Np, size_t Nn);
#endif
#if defined(MBEDTLS_ECP_DP_SECP224R1_ENABLED)
static int ecp_mod_p224(mbedtls_mpi *);
@ -4884,10 +4886,12 @@ static inline void carry64(mbedtls_mpi_uint *dst, mbedtls_mpi_uint *carry)
}
#define WIDTH 8 / sizeof(mbedtls_mpi_uint)
#define A(i) N->p + (i) * WIDTH
#define ADD(i) add64(p, A(i), &c)
#define A(i) Np + (i) * WIDTH
#define ADD(i) add64(p, A(i), &c)
#define NEXT p += WIDTH; carry64(p, &c)
#define LAST p += WIDTH; *p = c; while (++p < end) *p = 0
#define RESET last_carry[0] = c; c = 0; p = Np
#define ADD_LAST add64(p, last_carry, &c)
/*
* Fast quasi-reduction modulo p192 (FIPS 186-3 D.2.1)
@ -4895,28 +4899,51 @@ static inline void carry64(mbedtls_mpi_uint *dst, mbedtls_mpi_uint *carry)
static int ecp_mod_p192(mbedtls_mpi *N)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_mpi_uint c = 0;
mbedtls_mpi_uint *p, *end;
/* Make sure we have enough blocks so that A(5) is legal */
MBEDTLS_MPI_CHK(mbedtls_mpi_grow(N, 6 * WIDTH));
p = N->p;
end = p + N->n;
ADD(3); ADD(5); NEXT; // A0 += A3 + A5
ADD(3); ADD(4); ADD(5); NEXT; // A1 += A3 + A4 + A5
ADD(4); ADD(5); LAST; // A2 += A4 + A5
size_t expected_width = 2 * ((192 + biL - 1) / biL);
MBEDTLS_MPI_CHK(mbedtls_mpi_grow(N, expected_width));
ret = mbedtls_ecp_mod_p192_raw(N->p, expected_width);
cleanup:
return ret;
}
MBEDTLS_STATIC_TESTABLE
int mbedtls_ecp_mod_p192_raw(mbedtls_mpi_uint *Np, size_t Nn)
{
mbedtls_mpi_uint c = 0, last_carry[WIDTH] = { 0 };
mbedtls_mpi_uint *p, *end;
if (Nn != 2*((192 + biL - 1)/biL)) {
return MBEDTLS_ERR_ECP_BAD_INPUT_DATA;
}
p = Np;
end = p + Nn;
ADD(3); ADD(5); NEXT; // A0 += A3 + A5
ADD(3); ADD(4); ADD(5); NEXT; // A1 += A3 + A4 + A5
ADD(4); ADD(5); // A2 += A4 + A5
RESET;
/* Use the reduction for the carry as well:
* 2^192 * last_carry = 2^64 * last_carry + last_carry mod P192
*/
ADD_LAST; NEXT; // A0 += last_carry
ADD_LAST; NEXT; // A1 += last_carry
LAST; // A2 += carry
return 0;
}
#undef WIDTH
#undef A
#undef ADD
#undef NEXT
#undef LAST
#undef RESET
#undef ADD_LAST
#endif /* MBEDTLS_ECP_DP_SECP192R1_ENABLED */
#if defined(MBEDTLS_ECP_DP_SECP224R1_ENABLED) || \