# rsa.c   [plain text]

```/*
*
* rsa.c
*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
*
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
*
* Created: Fri Mar  3 22:07:06 1995 ylo
*
* Description of the RSA algorithm can be found e.g. from the following sources:
*
*   Bruce Schneier: Applied Cryptography.  John Wiley & Sons, 1994.
*
*   Jennifer Seberry and Josed Pieprzyk: Cryptography: An Introduction to
*   Computer Security.  Prentice-Hall, 1989.
*
*   Man Young Rhee: Cryptography and Secure Data Communications.  McGraw-Hill,
*   1994.
*
*   R. Rivest, A. Shamir, and L. M. Adleman: Cryptographic Communications
*   System and Method.  US Patent 4,405,829, 1983.
*
*   Hans Riesel: Prime Numbers and Computer Methods for Factorization.
*   Birkhauser, 1994.
*
*   The RSA Frequently Asked Questions document by RSA Data Security, Inc., 1995.
*
*   RSA in 3 lines of perl by Adam Back <aba@atlax.ex.ac.uk>, 1995, as included
*   below:
*
*     [gone - had to be deleted - what a pity]
*
*/

//#include "includes.h"
//RCSID("\$OpenBSD: rsa.c,v 1.15 2000/06/20 01:39:44 markus Exp \$");
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#include "rsa.h"
//#include "ssh.h"
#include "xmalloc.h"
#include "entropy.h"

int rsa_verbose = 1;

int
rsa_alive()
{
RSA *key;

seed_rng();
key = RSA_generate_key(32, 3, NULL, NULL);
if (key == NULL)
return (0);
RSA_free(key);
return (1);
}

/*
* Key generation progress meter callback
*/
void
keygen_progress(int p, int n, void *arg)
{
const char progress_chars[] = ".o+O?";

if ((p < 0) || (p > (sizeof(progress_chars) - 2)))
p = sizeof(progress_chars) - 2;

putchar(progress_chars[p]);
fflush(stdout);
}

/*
* Generates RSA public and private keys.  This initializes the data
* structures; they should be freed with rsa_clear_private_key and
* rsa_clear_public_key.
*/

void
rsa_generate_key(RSA *prv, RSA *pub, unsigned int bits)
{
RSA *key;

seed_rng();

if (rsa_verbose) {
printf("Generating RSA keys:  ");
fflush(stdout);
key = RSA_generate_key(bits, 35, keygen_progress, NULL);
printf("\n");
} else {
key = RSA_generate_key(bits, 35, NULL, NULL);
}
if (key == NULL) {
//fatal("rsa_generate_key: key generation failed.");
return;
}

/* Copy public key parameters */
pub->n = BN_new();
BN_copy(pub->n, key->n);
pub->e = BN_new();
BN_copy(pub->e, key->e);

/* Copy private key parameters */
prv->n = BN_new();
BN_copy(prv->n, key->n);
prv->e = BN_new();
BN_copy(prv->e, key->e);
prv->d = BN_new();
BN_copy(prv->d, key->d);
prv->p = BN_new();
BN_copy(prv->p, key->p);
prv->q = BN_new();
BN_copy(prv->q, key->q);

prv->dmp1 = BN_new();
BN_copy(prv->dmp1, key->dmp1);

prv->dmq1 = BN_new();
BN_copy(prv->dmq1, key->dmq1);

prv->iqmp = BN_new();
BN_copy(prv->iqmp, key->iqmp);

RSA_free(key);

if (rsa_verbose)
printf("Key generation complete.\n");
}

void
rsa_public_encrypt(BIGNUM *out, BIGNUM *in, RSA *key)
{
unsigned char *inbuf, *outbuf;
int len, ilen, olen;

if (BN_num_bits(key->e) < 2 || !BN_is_odd(key->e)) {
//fatal("rsa_public_encrypt() exponent too small or not odd");
return;
}

olen = BN_num_bytes(key->n);
outbuf = xmalloc(olen);

ilen = BN_num_bytes(in);
inbuf = xmalloc(ilen);
BN_bn2bin(in, inbuf);

if ((len = RSA_public_encrypt(ilen, inbuf, outbuf, key, RSA_PKCS1_PADDING)) <= 0) {
//fatal("rsa_public_encrypt() failed");
return;
}

BN_bin2bn(outbuf, len, out);

memset(outbuf, 0, olen);
memset(inbuf, 0, ilen);
xfree(outbuf);
xfree(inbuf);
}

void
rsa_private_decrypt(BIGNUM *out, BIGNUM *in, RSA *key)
{
unsigned char *inbuf, *outbuf;
int len, ilen, olen;

olen = BN_num_bytes(key->n);
outbuf = xmalloc(olen);

ilen = BN_num_bytes(in);
inbuf = xmalloc(ilen);
BN_bn2bin(in, inbuf);

if ((len = RSA_private_decrypt(ilen, inbuf, outbuf, key, RSA_PKCS1_PADDING)) <= 0) {
//fatal("rsa_private_decrypt() failed");
return;
}

BN_bin2bn(outbuf, len, out);

memset(outbuf, 0, olen);
memset(inbuf, 0, ilen);
xfree(outbuf);
xfree(inbuf);
}

/* Set whether to output verbose messages during key generation. */

void
rsa_set_verbose(int verbose)
{
rsa_verbose = verbose;
}
```