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ec_cvt.c: performance update from HEAD.

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This commit is contained in:
Andy Polyakov 2011-11-14 21:14:53 +00:00
parent d807d4c21f
commit 17674bfdf7
1 changed files with 25 additions and 0 deletions
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crypto/ec/ec_cvt.c
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@ -78,7 +78,32 @@ EC_GROUP *EC_GROUP_new_curve_GFp(const BIGNUM *p, const BIGNUM *a, const BIGNUM
const EC_METHOD *meth;
EC_GROUP *ret;
#if defined(OPENSSL_BN_ASM_MONT)
/*
* This might appear controversial, but the fact is that generic
* prime method was observed to deliver better performance even
* for NIST primes on a range of platforms, e.g.: 60%-15%
* improvement on IA-64, ~25% on ARM, 30%-90% on P4, 20%-25%
* in 32-bit build and 35%--12% in 64-bit build on Core2...
* Coefficients are relative to optimized bn_nist.c for most
* intensive ECDSA verify and ECDH operations for 192- and 521-
* bit keys respectively. Choice of these boundary values is
* arguable, because the dependency of improvement coefficient
* from key length is not a "monotone" curve. For example while
* 571-bit result is 23% on ARM, 384-bit one is -1%. But it's
* generally faster, sometimes "respectfully" faster, sometimes
* "tolerably" slower... What effectively happens is that loop
* with bn_mul_add_words is put against bn_mul_mont, and the
* latter "wins" on short vectors. Correct solution should be
* implementing dedicated NxN multiplication subroutines for
* small N. But till it materializes, let's stick to generic
* prime method...
* <appro>
*/
meth = EC_GFp_mont_method();
#else
meth = EC_GFp_nist_method();
#endif
ret = EC_GROUP_new(meth);
if (ret == NULL)