static int
rsa_private_calculate(mpz_t in, mpz_t p, mpz_t q,
mpz_t dmp1, mpz_t dmq1, mpz_t iqmp,
mpz_t out)
{
mpz_t vp, vq, u;
mpz_init(vp); mpz_init(vq); mpz_init(u);
/* vq = c ^ (d mod (q - 1)) mod q */
/* vp = c ^ (d mod (p - 1)) mod p */
mpz_fdiv_r(vp, in, p);
mpz_powm(vp, vp, dmp1, p);
mpz_fdiv_r(vq, in, q);
mpz_powm(vq, vq, dmq1, q);
/* C2 = 1/q mod p (iqmp) */
/* u = (vp - vq)C2 mod p. */
mpz_sub(u, vp, vq);
#if 0
if (mp_int_compare_zero(&u) < 0)
mp_int_add(&u, p, &u);
#endif
mpz_mul(u, iqmp, u);
mpz_fdiv_r(u, u, p);
/* c ^ d mod n = vq + u q */
mpz_mul(u, q, u);
mpz_add(out, u, vq);
mpz_clear(vp);
mpz_clear(vq);
mpz_clear(u);
return 0;
}
static mp_result s_rsa_transform(mp_int msg, mp_int exp,
mp_int mod, mp_int out)
{
if(mp_int_compare_zero(msg) < 0 ||
mp_int_compare(msg, mod) >= 0)
return MP_RANGE;
return mp_int_exptmod(msg, exp, mod, out);
}
/*
Compute mul * atan(1/x) to prec digits of precision, and store the
result in sum.
Computes atan(1/x) using the formula:
1 1 1 1
atan(1/x) = --- - ---- + ---- - ---- + ...
x 3x^3 5x^5 7x^7
*/
mp_result arctan(mp_small radix, mp_small mul, mp_small x, mp_small prec,
mp_int sum) {
mpz_t t, v;
mp_result res;
mp_small rem, sign = 1, coeff = 1;
mp_int_init(&t);
mp_int_init(&v);
++prec;
/* Compute mul * radix^prec * x
The initial multiplication by x saves a special case in the loop for
the first term of the series.
*/
if ((res = mp_int_expt_value(radix, prec, &t)) != MP_OK ||
(res = mp_int_mul_value(&t, mul, &t)) != MP_OK ||
(res = mp_int_mul_value(&t, x, &t)) != MP_OK)
goto CLEANUP;
x *= x; /* assumes x <= sqrt(MP_SMALL_MAX) */
mp_int_zero(sum);
do {
if ((res = mp_int_div_value(&t, x, &t, &rem)) != MP_OK) goto CLEANUP;
if ((res = mp_int_div_value(&t, coeff, &v, &rem)) != MP_OK) goto CLEANUP;
/* Add or subtract the result depending on the current sign (1 = add) */
if (sign > 0)
res = mp_int_add(sum, &v, sum);
else
res = mp_int_sub(sum, &v, sum);
if (res != MP_OK) goto CLEANUP;
sign = -sign;
coeff += 2;
} while (mp_int_compare_zero(&t) != 0);
res = mp_int_div_value(sum, radix, sum, NULL);
CLEANUP:
mp_int_clear(&v);
mp_int_clear(&t);
return res;
}
static int
gmp_rsa_private_decrypt(int flen, const unsigned char* from,
unsigned char* to, RSA* rsa, int padding)
{
unsigned char *ptr;
size_t size;
mpz_t in, out, n, e;
if (padding != RSA_PKCS1_PADDING)
return -1;
size = RSA_size(rsa);
if (flen > size)
return -2;
mpz_init(in);
mpz_init(out);
BN2mpz(n, rsa->n);
BN2mpz(e, rsa->e);
mpz_import(in, flen, 1, 1, 1, 0, from);
if(mpz_cmp_ui(in, 0) < 0 ||
mpz_cmp(in, n) >= 0) {
size = 0;
goto out;
}
if (rsa->p && rsa->q && rsa->dmp1 && rsa->dmq1 && rsa->iqmp) {
mpz_t p, q, dmp1, dmq1, iqmp;
BN2mpz(p, rsa->p);
BN2mpz(q, rsa->q);
BN2mpz(dmp1, rsa->dmp1);
BN2mpz(dmq1, rsa->dmq1);
BN2mpz(iqmp, rsa->iqmp);
rsa_private_calculate(in, p, q, dmp1, dmq1, iqmp, out);
mpz_clear(p);
mpz_clear(q);
mpz_clear(dmp1);
mpz_clear(dmq1);
mpz_clear(iqmp);
} else {
mpz_t d;
#if 0
if(mp_int_compare_zero(&in) < 0 ||
mp_int_compare(&in, &n) >= 0)
return MP_RANGE;
#endif
BN2mpz(d, rsa->d);
mpz_powm(out, in, d, n);
mpz_clear(d);
}
ptr = to;
{
size_t ssize;
mpz_export(ptr, &ssize, 1, 1, 1, 0, out);
assert(size >= ssize);
size = ssize;
}
/* head zero was skipped by mp_int_to_unsigned */
if (*ptr != 2)
return -3;
size--; ptr++;
while (size && *ptr != 0) {
size--; ptr++;
}
if (size == 0)
return -4;
size--; ptr++;
memmove(to, ptr, size);
out:
mpz_clear(e);
mpz_clear(n);
mpz_clear(in);
mpz_clear(out);
return size;
}
static int
gmp_rsa_private_encrypt(int flen, const unsigned char* from,
unsigned char* to, RSA* rsa, int padding)
{
unsigned char *p, *p0;
size_t size;
mpz_t in, out, n, e;
if (padding != RSA_PKCS1_PADDING)
return -1;
size = RSA_size(rsa);
if (size < RSA_PKCS1_PADDING_SIZE || size - RSA_PKCS1_PADDING_SIZE < flen)
return -2;
p0 = p = malloc(size);
*p++ = 0;
*p++ = 1;
memset(p, 0xff, size - flen - 3);
p += size - flen - 3;
*p++ = 0;
memcpy(p, from, flen);
p += flen;
assert((p - p0) == size);
BN2mpz(n, rsa->n);
BN2mpz(e, rsa->e);
mpz_init(in);
mpz_init(out);
mpz_import(in, size, 1, 1, 1, 0, p0);
free(p0);
#if 0
if(mp_int_compare_zero(&in) < 0 ||
mp_int_compare(&in, &n) >= 0) {
size = 0;
goto out;
}
#endif
if (rsa->p && rsa->q && rsa->dmp1 && rsa->dmq1 && rsa->iqmp) {
mpz_t p, q, dmp1, dmq1, iqmp;
BN2mpz(p, rsa->p);
BN2mpz(q, rsa->q);
BN2mpz(dmp1, rsa->dmp1);
BN2mpz(dmq1, rsa->dmq1);
BN2mpz(iqmp, rsa->iqmp);
rsa_private_calculate(in, p, q, dmp1, dmq1, iqmp, out);
mpz_clear(p);
mpz_clear(q);
mpz_clear(dmp1);
mpz_clear(dmq1);
mpz_clear(iqmp);
} else {
mpz_t d;
BN2mpz(d, rsa->d);
mpz_powm(out, in, d, n);
mpz_clear(d);
}
{
size_t ssize;
mpz_export(to, &ssize, 1, 1, 1, 0, out);
assert(size >= ssize);
size = ssize;
}
mpz_clear(e);
mpz_clear(n);
mpz_clear(in);
mpz_clear(out);
return size;
}
