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Merge pull request #7351 from gabor-mezei-arm/7109_ecp_fast_reduction_testing

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Test unlikely cases of ECC modular reduction
This commit is contained in:
Janos Follath
2023-04-06 15:55:19 +01:00
committed by GitHub
parent bcf2f66a11 d8c0e1aa8d
commit 44c6694be7
2 changed files with 170 additions and 100 deletions
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14
library/ecp_curves.c
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@@ -4897,7 +4897,7 @@ static inline void carry64(mbedtls_mpi_uint *dst, mbedtls_mpi_uint *carry)
#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 LAST p += WIDTH; do *p = 0; while (++p < end)
#define RESET last_carry[0] = c; c = 0; p = Np
#define ADD_LAST add64(p, last_carry, &c)
@@ -4934,13 +4934,23 @@ int mbedtls_ecp_mod_p192_raw(mbedtls_mpi_uint *Np, size_t Nn)
RESET;
/* Use the reduction for the carry as well:
* 2^192 * last_carry = 2^64 * last_carry + last_carry mod P192
* It can generate a carry. */
ADD_LAST; NEXT; // A0 += last_carry
ADD_LAST; NEXT; // A1 += last_carry
// A2 += carry
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
// A2 += carry
LAST; // A2 += carry
LAST;
return 0;
}