diff options
| -rw-r--r-- | crypto/ecc.c | 25 | ||||
| -rw-r--r-- | include/crypto/internal/ecc.h | 3 |
2 files changed, 27 insertions, 1 deletions
diff --git a/crypto/ecc.c b/crypto/ecc.c index e94183f6c418..8914e437f94b 100644 --- a/crypto/ecc.c +++ b/crypto/ecc.c @@ -902,6 +902,28 @@ static void vli_mmod_fast_384(u64 *result, const u64 *product, #undef AND64H #undef AND64L +/* + * Computes result = product % curve_prime + * from "Recommendations for Discrete Logarithm-Based Cryptography: + * Elliptic Curve Domain Parameters" section G.1.4 + */ +static void vli_mmod_fast_521(u64 *result, const u64 *product, + const u64 *curve_prime, u64 *tmp) +{ + const unsigned int ndigits = ECC_CURVE_NIST_P521_DIGITS; + size_t i; + + /* Initialize result with lowest 521 bits from product */ + vli_set(result, product, ndigits); + result[8] &= 0x1ff; + + for (i = 0; i < ndigits; i++) + tmp[i] = (product[8 + i] >> 9) | (product[9 + i] << 55); + tmp[8] &= 0x1ff; + + vli_mod_add(result, result, tmp, curve_prime, ndigits); +} + /* Computes result = product % curve_prime for different curve_primes. * * Note that curve_primes are distinguished just by heuristic check and @@ -941,6 +963,9 @@ static bool vli_mmod_fast(u64 *result, u64 *product, case ECC_CURVE_NIST_P384_DIGITS: vli_mmod_fast_384(result, product, curve_prime, tmp); break; + case ECC_CURVE_NIST_P521_DIGITS: + vli_mmod_fast_521(result, product, curve_prime, tmp); + break; default: pr_err_ratelimited("ecc: unsupported digits size!\n"); return false; diff --git a/include/crypto/internal/ecc.h b/include/crypto/internal/ecc.h index ab722a8986b7..4e2f5f938e91 100644 --- a/include/crypto/internal/ecc.h +++ b/include/crypto/internal/ecc.h @@ -33,7 +33,8 @@ #define ECC_CURVE_NIST_P192_DIGITS 3 #define ECC_CURVE_NIST_P256_DIGITS 4 #define ECC_CURVE_NIST_P384_DIGITS 6 -#define ECC_MAX_DIGITS (512 / 64) /* due to ecrdsa */ +#define ECC_CURVE_NIST_P521_DIGITS 9 +#define ECC_MAX_DIGITS DIV_ROUND_UP(521, 64) /* NIST P521 */ #define ECC_DIGITS_TO_BYTES_SHIFT 3 |