static int e_gmp_rsa_mod_exp(BIGNUM *r, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
{
E_GMP_RSA_CTX *hptr;
int to_return = 0;
hptr = e_gmp_get_rsa(rsa);
if(!hptr)
{
GMPerr(GMP_F_E_GMP_RSA_MOD_EXP,
GMP_R_KEY_CONTEXT_ERROR);
return 0;
}
if(hptr->public_only)
{
GMPerr(GMP_F_E_GMP_RSA_MOD_EXP,
GMP_R_MISSING_KEY_COMPONENTS);
return 0;
}
/* ugh!!! */
if(!bn2gmp(I, hptr->I0))
return 0;
/* This is basically the CRT logic in crypto/rsa/rsa_eay.c reworded into
* GMP-speak. It may be that GMP's API facilitates cleaner formulations
* of this stuff, eg. better handling of negatives, or functions that
* combine operations. */
mpz_mod(hptr->r1, hptr->I0, hptr->q);
mpz_powm(hptr->m1, hptr->r1, hptr->dmq1, hptr->q);
mpz_mod(hptr->r1, hptr->I0, hptr->p);
mpz_powm(hptr->r0, hptr->r1, hptr->dmp1, hptr->p);
mpz_sub(hptr->r0, hptr->r0, hptr->m1);
if(mpz_sgn(hptr->r0) < 0)
mpz_add(hptr->r0, hptr->r0, hptr->p);
mpz_mul(hptr->r1, hptr->r0, hptr->iqmp);
mpz_mod(hptr->r0, hptr->r1, hptr->p);
if(mpz_sgn(hptr->r0) < 0)
mpz_add(hptr->r0, hptr->r0, hptr->p);
mpz_mul(hptr->r1, hptr->r0, hptr->q);
mpz_add(hptr->r0, hptr->r1, hptr->m1);
/* ugh!!! */
if(gmp2bn(hptr->r0, r))
to_return = 1;
return 1;
}
static int e_gmp_ctrl(ENGINE *e, int cmd, long i, void *p, void (*f) (void))
{
int to_return = 1;
switch (cmd) {
/* The command isn't understood by this engine */
default:
GMPerr(GMP_F_E_GMP_CTRL, GMP_R_CTRL_COMMAND_NOT_IMPLEMENTED);
to_return = 0;
break;
}
return to_return;
}
