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Ah, ok so my problem had been typographical rather than philosophical.

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It's cute to observe that Atalla having no RSA-specific form of mod_exp
causes a DSA server to achieve about 6 times as many signatures per
second than an RSA server. :-)
This commit is contained in:
Geoff Thorpe 2000-06-15 17:14:45 +00:00
parent f18ef82a9f
commit 8e2c277353
1 changed files with 8 additions and 10 deletions
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18
crypto/engine/hw_atalla.c
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@ -384,15 +384,16 @@ err:
}
/* This code was liberated and adapted from the commented-out code in
* dsa_ossl.c but doesn't work (for me at least). So I need to work out
* some mod_exp-based variant of BN_mod_exp2_mont ... for now we resort
* to software which should only hurt DSA clients, or DSA servers doing
* client-authentication. */
* dsa_ossl.c. Because of the unoptimised form of the Atalla acceleration
* (it doesn't have a CRT form for RSA), this function means that an
* Atalla system running with a DSA server certificate can handshake
* around 5 or 6 times faster/more than an equivalent system running with
* RSA. Just check out the "signs" statistics from the RSA and DSA parts
* of "openssl speed -engine atalla dsa1024 rsa1024". */
static int atalla_dsa_mod_exp(DSA *dsa, BIGNUM *rr, BIGNUM *a1,
BIGNUM *p1, BIGNUM *a2, BIGNUM *p2, BIGNUM *m,
BN_CTX *ctx, BN_MONT_CTX *in_mont)
{
#if 0
BIGNUM t;
int to_return = 0;
@ -401,15 +402,12 @@ static int atalla_dsa_mod_exp(DSA *dsa, BIGNUM *rr, BIGNUM *a1,
if (!atalla_mod_exp(rr,a1,p1,m,ctx)) goto end;
/* let t = a2 ^ p2 mod m */
if (!atalla_mod_exp(&t,a2,p2,m,ctx)) goto end;
/* let p1 = rr * t mod m */
if (!BN_mod_mul(p1,rr,&t,m,ctx)) goto end;
/* let rr = rr * t mod m */
if (!BN_mod_mul(rr,rr,&t,m,ctx)) goto end;
to_return = 1;
end:
BN_free(&t);
return to_return;
#else
return BN_mod_exp2_mont(rr, a1, p1, a2, p2, m, ctx, in_mont);
#endif
}