/* This code was liberated and adapted from the commented-out code in
* 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)
{
BIGNUM t;
int to_return = 0;
BN_init(&t);
/* let rr = a1 ^ p1 mod m */
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 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;
}
static int atalla_rsa_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
{
int to_return = 0;
if(!atalla_dso)
{
ATALLAerr(ATALLA_F_ATALLA_RSA_MOD_EXP,ATALLA_R_NOT_LOADED);
goto err;
}
if(!rsa->d || !rsa->n)
{
ATALLAerr(ATALLA_F_ATALLA_RSA_MOD_EXP,ATALLA_R_MISSING_KEY_COMPONENTS);
goto err;
}
to_return = atalla_mod_exp(r0, I, rsa->d, rsa->n, ctx);
err:
return to_return;
}
static int atalla_rsa_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa)
{
BN_CTX *ctx = NULL;
int to_return = 0;
if(!atalla_dso)
{
ATALLAerr(ATALLA_F_ATALLA_RSA_MOD_EXP,ATALLA_R_NOT_LOADED);
goto err;
}
if((ctx = BN_CTX_new()) == NULL)
goto err;
if(!rsa->d || !rsa->n)
{
ATALLAerr(ATALLA_F_ATALLA_RSA_MOD_EXP,ATALLA_R_MISSING_KEY_COMPONENTS);
goto err;
}
to_return = atalla_mod_exp(r0, I, rsa->d, rsa->n, ctx);
err:
if(ctx)
BN_CTX_free(ctx);
return to_return;
}
/* This function is aliased to mod_exp (with the dh and mont dropped). */
static int atalla_mod_exp_dh(const DH *dh, BIGNUM *r,
const BIGNUM *a, const BIGNUM *p,
const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx)
{
return atalla_mod_exp(r, a, p, m, ctx);
}
static int atalla_mod_exp_dsa(DSA *dsa, BIGNUM *r, BIGNUM *a,
const BIGNUM *p, const BIGNUM *m, BN_CTX *ctx,
BN_MONT_CTX *m_ctx)
{
return atalla_mod_exp(r, a, p, m, ctx);
}
