private-from-pq.c

#include <stdlib.h>
#include <openssl/bn.h>
#include <openssl/rsa.h>
#include <openssl/engine.h>
#include <openssl/pem.h>

const int L = 4 << 20;
char sp[L], sq[L];

int main (int argc, char *argv[])
{
    freopen("p.txt","r",stdin);
    gets(sp);
    freopen("q.txt","r",stdin);
    gets(sq);
    argc=3;
    argv[1]=sp;
    argv[2]=sq;

    BIGNUM *n = BN_new ();
    BIGNUM *d = BN_new ();
    BIGNUM *e = BN_new ();
    BIGNUM *p = BN_new ();
    BIGNUM *q = BN_new ();
    BIGNUM *p1 = BN_new ();
    BIGNUM *q1 = BN_new ();
    BIGNUM *dmp1 = BN_new ();
    BIGNUM *dmq1 = BN_new ();
    BIGNUM *iqmp = BN_new ();
    BIGNUM *phi = BN_new ();
    BN_CTX *ctx = BN_CTX_new ();
    RSA *key = RSA_new ();

    if (argc < 3)
    {
        fprintf (stderr, "usage: %s p q\n", argv[0]);
        exit (1);
    }
    fprintf(stderr,"LINE %d\n",__LINE__);

    if (!(BN_dec2bn (&p, argv[1])) || !(BN_dec2bn (&q, argv[2]))) {
        fprintf (stderr, "usage: %s p q\n", argv[0]);
        exit (1);
    }

    fprintf(stderr,"LINE %d\n",__LINE__);

    /* if (!(BN_is_prime (p, BN_prime_checks, NULL, ctx, NULL)) || */
            /* !(BN_is_prime (q, BN_prime_checks, NULL, ctx, NULL))) { */
        /* fprintf (stderr, "Arguments must both be prime!\n", argv[0]); */
        /* exit (1); */
    /* } */
    fprintf(stderr,"LINE %d\n",__LINE__);

    BN_dec2bn (&e, "65537");
    fprintf(stderr,"LINE %d\n",__LINE__);

    /* Calculate RSA private key parameters */

    /* n = p*q */
    BN_mul (n, p, q, ctx);
    fprintf(stderr,"LINE %d\n",__LINE__);
    /* p1 = p-1 */
    BN_sub (p1, p, BN_value_one ());
    fprintf(stderr,"LINE %d\n",__LINE__);
    /* q1 = q-1 */
    BN_sub (q1, q, BN_value_one ());
    fprintf(stderr,"LINE %d\n",__LINE__);
    /* phi(pq) = (p-1)*(q-1) */
    BN_mul (phi, p1, q1, ctx);
    fprintf(stderr,"LINE %d\n",__LINE__);
    /* d = e^-1 mod phi */
    BN_mod_inverse (d, e, phi, ctx);
    fprintf(stderr,"LINE %d\n",__LINE__);
    /* dmp1 = d mod (p-1) */
    BN_mod (dmp1, d, p1, ctx);
    fprintf(stderr,"LINE %d\n",__LINE__);
    /* dmq1 = d mod (q-1) */
    BN_mod (dmq1, d, q1, ctx);
    fprintf(stderr,"LINE %d\n",__LINE__);
    /* iqmp = q^-1 mod p */
    BN_mod_inverse (iqmp, q, p, ctx);
    fprintf(stderr,"LINE %d\n",__LINE__);

    /* Populate key data structure */
    key->n = n;
    key->e = e;
    key->d = d;
    key->p = p;
    key->q = q;
    key->dmp1 = dmp1;
    key->dmq1 = dmq1;
    key->iqmp = iqmp;
    fprintf(stderr,"LINE %d\n",__LINE__);

    /* Output the private key in human-readable and PEM forms */
    RSA_print_fp (stdout, key, 5);
    fprintf(stderr,"LINE %d\n",__LINE__);
    printf("\n");
    PEM_write_RSAPrivateKey (stdout, key, NULL, NULL, 0, 0, NULL);
    fprintf(stderr,"LINE %d\n",__LINE__);

    /* Release allocated objects */
    BN_CTX_free (ctx);
    RSA_free(key); /* also frees n, e, d, p, q, dmp1, dmq1, iqmp */
    BN_clear_free (phi);
    BN_clear_free (p1);
    BN_clear_free (q1);
    fprintf(stderr,"LINE %d\n",__LINE__);
    return 0;
}