demos/pkey/EVP_PKEY_RSA_keygen.c - third_party/openssl - Git at Google

 /*-
  * Copyright 2022 The OpenSSL Project Authors. All Rights Reserved.
  *
  * Licensed under the Apache License 2.0 (the "License").  You may not use
  * this file except in compliance with the License.  You can obtain a copy
  * in the file LICENSE in the source distribution or at
  * https://www.openssl.org/source/license.html
  */

 /*
  * Example showing how to generate an RSA key pair.
  *
  * When generating an RSA key, you must specify the number of bits in the key. A
  * reasonable value would be 4096. Avoid using values below 2048. These values
  * are reasonable as of 2022.
  */

 #include <string.h>
 #include <stdio.h>
 #include <openssl/err.h>
 #include <openssl/evp.h>
 #include <openssl/rsa.h>
 #include <openssl/core_names.h>
 #include <openssl/pem.h>

 /* A property query used for selecting algorithm implementations. */
 static const char *propq = NULL;

 /*
  * Generates an RSA public-private key pair and returns it.
  * The number of bits is specified by the bits argument.
  *
  * This uses the long way of generating an RSA key.
  */
 static EVP_PKEY *generate_rsa_key_long(OSSL_LIB_CTX *libctx, unsigned int bits)
 {
     EVP_PKEY_CTX *genctx = NULL;
     EVP_PKEY *pkey = NULL;
     unsigned int primes = 2;

     /* Create context using RSA algorithm. "RSA-PSS" could also be used here. */
     genctx = EVP_PKEY_CTX_new_from_name(libctx, "RSA", propq);
     if (genctx == NULL) {
         fprintf(stderr, "EVP_PKEY_CTX_new_from_name() failed\n");
         goto cleanup;
     }

     /* Initialize context for key generation purposes. */
     if (EVP_PKEY_keygen_init(genctx) <= 0) {
         fprintf(stderr, "EVP_PKEY_keygen_init() failed\n");
         goto cleanup;
     }

     /*
      * Here we set the number of bits to use in the RSA key.
      * See comment at top of file for information on appropriate values.
      */
     if (EVP_PKEY_CTX_set_rsa_keygen_bits(genctx, bits) <= 0) {
         fprintf(stderr, "EVP_PKEY_CTX_set_rsa_keygen_bits() failed\n");
         goto cleanup;
     }

     /*
      * It is possible to create an RSA key using more than two primes.
      * Do not do this unless you know why you need this.
      * You ordinarily do not need to specify this, as the default is two.
      *
      * Both of these parameters can also be set via EVP_PKEY_CTX_set_params, but
      * these functions provide a more concise way to do so.
      */
     if (EVP_PKEY_CTX_set_rsa_keygen_primes(genctx, primes) <= 0) {
         fprintf(stderr, "EVP_PKEY_CTX_set_rsa_keygen_primes() failed\n");
         goto cleanup;
     }

     /*
      * Generating an RSA key with a number of bits large enough to be secure for
      * modern applications can take a fairly substantial amount of time (e.g.
      * one second). If you require fast key generation, consider using an EC key
      * instead.
      *
      * If you require progress information during the key generation process,
      * you can set a progress callback using EVP_PKEY_set_cb; see the example in
      * EVP_PKEY_generate(3).
      */
     fprintf(stderr, "Generating RSA key, this may take some time...\n");
     if (EVP_PKEY_generate(genctx, &pkey) <= 0) {
         fprintf(stderr, "EVP_PKEY_generate() failed\n");
         goto cleanup;
     }

     /* pkey is now set to an object representing the generated key pair. */

 cleanup:
     EVP_PKEY_CTX_free(genctx);
     return pkey;
 }

 /*
  * Generates an RSA public-private key pair and returns it.
  * The number of bits is specified by the bits argument.
  *
  * This uses a more concise way of generating an RSA key, which is suitable for
  * simple cases. It is used if -s is passed on the command line, otherwise the
  * long method above is used. The ability to choose between these two methods is
  * shown here only for demonstration; the results are equivalent.
  */
 static EVP_PKEY *generate_rsa_key_short(OSSL_LIB_CTX *libctx, unsigned int bits)
 {
     EVP_PKEY *pkey = NULL;

     fprintf(stderr, "Generating RSA key, this may take some time...\n");
     pkey = EVP_PKEY_Q_keygen(libctx, propq, "RSA", (size_t)bits);

     if (pkey == NULL)
         fprintf(stderr, "EVP_PKEY_Q_keygen() failed\n");

     return pkey;
 }

 /*
  * Prints information on an EVP_PKEY object representing an RSA key pair.
  */
 static int dump_key(const EVP_PKEY *pkey)
 {
     int rv = 0;
     int bits = 0;
     BIGNUM *n = NULL, *e = NULL, *d = NULL, *p = NULL, *q = NULL;

     /*
      * Retrieve value of n. This value is not secret and forms part of the
      * public key.
      *
      * Calling EVP_PKEY_get_bn_param with a NULL BIGNUM pointer causes
      * a new BIGNUM to be allocated, so these must be freed subsequently.
      */
     if (EVP_PKEY_get_bn_param(pkey, OSSL_PKEY_PARAM_RSA_N, &n) == 0) {
         fprintf(stderr, "Failed to retrieve n\n");
         goto cleanup;
     }

     /*
      * Retrieve value of e. This value is not secret and forms part of the
      * public key. It is typically 65537 and need not be changed.
      */
     if (EVP_PKEY_get_bn_param(pkey, OSSL_PKEY_PARAM_RSA_E, &e) == 0) {
         fprintf(stderr, "Failed to retrieve e\n");
         goto cleanup;
     }

     /*
      * Retrieve value of d. This value is secret and forms part of the private
      * key. It must not be published.
      */
     if (EVP_PKEY_get_bn_param(pkey, OSSL_PKEY_PARAM_RSA_D, &d) == 0) {
         fprintf(stderr, "Failed to retrieve d\n");
         goto cleanup;
     }

     /*
      * Retrieve value of the first prime factor, commonly known as p. This value
      * is secret and forms part of the private key. It must not be published.
      */
     if (EVP_PKEY_get_bn_param(pkey, OSSL_PKEY_PARAM_RSA_FACTOR1, &p) == 0) {
         fprintf(stderr, "Failed to retrieve p\n");
         goto cleanup;
     }

     /*
      * Retrieve value of the second prime factor, commonly known as q. This value
      * is secret and forms part of the private key. It must not be published.
      *
      * If you are creating an RSA key with more than two primes for special
      * applications, you can retrieve these primes with
      * OSSL_PKEY_PARAM_RSA_FACTOR3, etc.
      */
     if (EVP_PKEY_get_bn_param(pkey, OSSL_PKEY_PARAM_RSA_FACTOR2, &q) == 0) {
         fprintf(stderr, "Failed to retrieve q\n");
         goto cleanup;
     }

     /*
      * We can also retrieve the key size in bits for informational purposes.
      */
     if (EVP_PKEY_get_int_param(pkey, OSSL_PKEY_PARAM_BITS, &bits) == 0) {
         fprintf(stderr, "Failed to retrieve bits\n");
         goto cleanup;
     }

     /* Output hexadecimal representations of the BIGNUM objects. */
     fprintf(stdout, "\nNumber of bits: %d\n\n", bits);
     fprintf(stderr, "Public values:\n");
     fprintf(stdout, "  n = 0x");
     BN_print_fp(stdout, n);
     fprintf(stdout, "\n");

     fprintf(stdout, "  e = 0x");
     BN_print_fp(stdout, e);
     fprintf(stdout, "\n\n");

     fprintf(stdout, "Private values:\n");
     fprintf(stdout, "  d = 0x");
     BN_print_fp(stdout, d);
     fprintf(stdout, "\n");

     fprintf(stdout, "  p = 0x");
     BN_print_fp(stdout, p);
     fprintf(stdout, "\n");

     fprintf(stdout, "  q = 0x");
     BN_print_fp(stdout, q);
     fprintf(stdout, "\n\n");

     /* Output a PEM encoding of the public key. */
     if (PEM_write_PUBKEY(stdout, pkey) == 0) {
         fprintf(stderr, "Failed to output PEM-encoded public key\n");
         goto cleanup;
     }

     /*
      * Output a PEM encoding of the private key. Please note that this output is
      * not encrypted. You may wish to use the arguments to specify encryption of
      * the key if you are storing it on disk. See PEM_write_PrivateKey(3).
      */
     if (PEM_write_PrivateKey(stdout, pkey, NULL, NULL, 0, NULL, NULL) == 0) {
         fprintf(stderr, "Failed to output PEM-encoded private key\n");
         goto cleanup;
     }

     rv = 1;
 cleanup:
     BN_free(n); /* not secret */
     BN_free(e); /* not secret */
     BN_clear_free(d); /* secret - scrub before freeing */
     BN_clear_free(p); /* secret - scrub before freeing */
     BN_clear_free(q); /* secret - scrub before freeing */
     return rv;
 }

 int main(int argc, char **argv)
 {
     int rv = 1;
     OSSL_LIB_CTX *libctx = NULL;
     EVP_PKEY *pkey = NULL;
     unsigned int bits = 4096;
     int bits_i, use_short = 0;

     /* usage: [-s] [<bits>] */
     if (argc > 1 && strcmp(argv[1], "-s") == 0) {
         --argc;
         ++argv;
         use_short = 1;
     }

     if (argc > 1) {
         bits_i = atoi(argv[1]);
         if (bits < 512) {
             fprintf(stderr, "Invalid RSA key size\n");
             return 1;
         }

         bits = (unsigned int)bits_i;
     }

     /* Avoid using key sizes less than 2048 bits; see comment at top of file. */
     if (bits < 2048)
         fprintf(stderr, "Warning: very weak key size\n\n");

     /* Generate RSA key. */
     if (use_short)
         pkey = generate_rsa_key_short(libctx, bits);
     else
         pkey = generate_rsa_key_long(libctx, bits);

     if (pkey == NULL)
         goto cleanup;

     /* Dump the integers comprising the key. */
     if (dump_key(pkey) == 0) {
         fprintf(stderr, "Failed to dump key\n");
         goto cleanup;
     }

     rv = 0;
 cleanup:
     EVP_PKEY_free(pkey);
     OSSL_LIB_CTX_free(libctx);
     return rv;
 }
	/*-
	* Copyright 2022 The OpenSSL Project Authors. All Rights Reserved.
	*
	* Licensed under the Apache License 2.0 (the "License"). You may not use
	* this file except in compliance with the License. You can obtain a copy
	* in the file LICENSE in the source distribution or at
	* https://www.openssl.org/source/license.html
	*/

	/*
	* Example showing how to generate an RSA key pair.
	*
	* When generating an RSA key, you must specify the number of bits in the key. A
	* reasonable value would be 4096. Avoid using values below 2048. These values
	* are reasonable as of 2022.
	*/

	#include <string.h>
	#include <stdio.h>
	#include <openssl/err.h>
	#include <openssl/evp.h>
	#include <openssl/rsa.h>
	#include <openssl/core_names.h>
	#include <openssl/pem.h>

	/* A property query used for selecting algorithm implementations. */
	static const char *propq = NULL;

	/*
	* Generates an RSA public-private key pair and returns it.
	* The number of bits is specified by the bits argument.
	*
	* This uses the long way of generating an RSA key.
	*/
	static EVP_PKEY generate_rsa_key_long(OSSL_LIB_CTX libctx, unsigned int bits)
	{
	EVP_PKEY_CTX *genctx = NULL;
	EVP_PKEY *pkey = NULL;
	unsigned int primes = 2;

	/* Create context using RSA algorithm. "RSA-PSS" could also be used here. */
	genctx = EVP_PKEY_CTX_new_from_name(libctx, "RSA", propq);
	if (genctx == NULL) {
	fprintf(stderr, "EVP_PKEY_CTX_new_from_name() failed\n");
	goto cleanup;
	}

	/* Initialize context for key generation purposes. */
	if (EVP_PKEY_keygen_init(genctx) <= 0) {
	fprintf(stderr, "EVP_PKEY_keygen_init() failed\n");
	goto cleanup;
	}

	/*
	* Here we set the number of bits to use in the RSA key.
	* See comment at top of file for information on appropriate values.
	*/
	if (EVP_PKEY_CTX_set_rsa_keygen_bits(genctx, bits) <= 0) {
	fprintf(stderr, "EVP_PKEY_CTX_set_rsa_keygen_bits() failed\n");
	goto cleanup;
	}

	/*
	* It is possible to create an RSA key using more than two primes.
	* Do not do this unless you know why you need this.
	* You ordinarily do not need to specify this, as the default is two.
	*
	* Both of these parameters can also be set via EVP_PKEY_CTX_set_params, but
	* these functions provide a more concise way to do so.
	*/
	if (EVP_PKEY_CTX_set_rsa_keygen_primes(genctx, primes) <= 0) {
	fprintf(stderr, "EVP_PKEY_CTX_set_rsa_keygen_primes() failed\n");
	goto cleanup;
	}

	/*
	* Generating an RSA key with a number of bits large enough to be secure for
	* modern applications can take a fairly substantial amount of time (e.g.
	* one second). If you require fast key generation, consider using an EC key
	* instead.
	*
	* If you require progress information during the key generation process,
	* you can set a progress callback using EVP_PKEY_set_cb; see the example in
	* EVP_PKEY_generate(3).
	*/
	fprintf(stderr, "Generating RSA key, this may take some time...\n");
	if (EVP_PKEY_generate(genctx, &pkey) <= 0) {
	fprintf(stderr, "EVP_PKEY_generate() failed\n");
	goto cleanup;
	}

	/* pkey is now set to an object representing the generated key pair. */

	cleanup:
	EVP_PKEY_CTX_free(genctx);
	return pkey;
	}

	/*
	* Generates an RSA public-private key pair and returns it.
	* The number of bits is specified by the bits argument.
	*
	* This uses a more concise way of generating an RSA key, which is suitable for
	* simple cases. It is used if -s is passed on the command line, otherwise the
	* long method above is used. The ability to choose between these two methods is
	* shown here only for demonstration; the results are equivalent.
	*/
	static EVP_PKEY generate_rsa_key_short(OSSL_LIB_CTX libctx, unsigned int bits)
	{
	EVP_PKEY *pkey = NULL;

	fprintf(stderr, "Generating RSA key, this may take some time...\n");
	pkey = EVP_PKEY_Q_keygen(libctx, propq, "RSA", (size_t)bits);

	if (pkey == NULL)
	fprintf(stderr, "EVP_PKEY_Q_keygen() failed\n");

	return pkey;
	}

	/*
	* Prints information on an EVP_PKEY object representing an RSA key pair.
	*/
	static int dump_key(const EVP_PKEY *pkey)
	{
	int rv = 0;
	int bits = 0;
	BIGNUM n = NULL, e = NULL, d = NULL, p = NULL, *q = NULL;

	/*
	* Retrieve value of n. This value is not secret and forms part of the
	* public key.
	*
	* Calling EVP_PKEY_get_bn_param with a NULL BIGNUM pointer causes
	* a new BIGNUM to be allocated, so these must be freed subsequently.
	*/
	if (EVP_PKEY_get_bn_param(pkey, OSSL_PKEY_PARAM_RSA_N, &n) == 0) {
	fprintf(stderr, "Failed to retrieve n\n");
	goto cleanup;
	}

	/*
	* Retrieve value of e. This value is not secret and forms part of the
	* public key. It is typically 65537 and need not be changed.
	*/
	if (EVP_PKEY_get_bn_param(pkey, OSSL_PKEY_PARAM_RSA_E, &e) == 0) {
	fprintf(stderr, "Failed to retrieve e\n");
	goto cleanup;
	}

	/*
	* Retrieve value of d. This value is secret and forms part of the private
	* key. It must not be published.
	*/
	if (EVP_PKEY_get_bn_param(pkey, OSSL_PKEY_PARAM_RSA_D, &d) == 0) {
	fprintf(stderr, "Failed to retrieve d\n");
	goto cleanup;
	}

	/*
	* Retrieve value of the first prime factor, commonly known as p. This value
	* is secret and forms part of the private key. It must not be published.
	*/
	if (EVP_PKEY_get_bn_param(pkey, OSSL_PKEY_PARAM_RSA_FACTOR1, &p) == 0) {
	fprintf(stderr, "Failed to retrieve p\n");
	goto cleanup;
	}

	/*
	* Retrieve value of the second prime factor, commonly known as q. This value
	* is secret and forms part of the private key. It must not be published.
	*
	* If you are creating an RSA key with more than two primes for special
	* applications, you can retrieve these primes with
	* OSSL_PKEY_PARAM_RSA_FACTOR3, etc.
	*/
	if (EVP_PKEY_get_bn_param(pkey, OSSL_PKEY_PARAM_RSA_FACTOR2, &q) == 0) {
	fprintf(stderr, "Failed to retrieve q\n");
	goto cleanup;
	}

	/*
	* We can also retrieve the key size in bits for informational purposes.
	*/
	if (EVP_PKEY_get_int_param(pkey, OSSL_PKEY_PARAM_BITS, &bits) == 0) {
	fprintf(stderr, "Failed to retrieve bits\n");
	goto cleanup;
	}

	/* Output hexadecimal representations of the BIGNUM objects. */
	fprintf(stdout, "\nNumber of bits: %d\n\n", bits);
	fprintf(stderr, "Public values:\n");
	fprintf(stdout, " n = 0x");
	BN_print_fp(stdout, n);
	fprintf(stdout, "\n");

	fprintf(stdout, " e = 0x");
	BN_print_fp(stdout, e);
	fprintf(stdout, "\n\n");

	fprintf(stdout, "Private values:\n");
	fprintf(stdout, " d = 0x");
	BN_print_fp(stdout, d);
	fprintf(stdout, "\n");

	fprintf(stdout, " p = 0x");
	BN_print_fp(stdout, p);
	fprintf(stdout, "\n");

	fprintf(stdout, " q = 0x");
	BN_print_fp(stdout, q);
	fprintf(stdout, "\n\n");

	/* Output a PEM encoding of the public key. */
	if (PEM_write_PUBKEY(stdout, pkey) == 0) {
	fprintf(stderr, "Failed to output PEM-encoded public key\n");
	goto cleanup;
	}

	/*
	* Output a PEM encoding of the private key. Please note that this output is
	* not encrypted. You may wish to use the arguments to specify encryption of
	* the key if you are storing it on disk. See PEM_write_PrivateKey(3).
	*/
	if (PEM_write_PrivateKey(stdout, pkey, NULL, NULL, 0, NULL, NULL) == 0) {
	fprintf(stderr, "Failed to output PEM-encoded private key\n");
	goto cleanup;
	}

	rv = 1;
	cleanup:
	BN_free(n); /* not secret */
	BN_free(e); /* not secret */
	BN_clear_free(d); /* secret - scrub before freeing */
	BN_clear_free(p); /* secret - scrub before freeing */
	BN_clear_free(q); /* secret - scrub before freeing */
	return rv;
	}

	int main(int argc, char **argv)
	{
	int rv = 1;
	OSSL_LIB_CTX *libctx = NULL;
	EVP_PKEY *pkey = NULL;
	unsigned int bits = 4096;
	int bits_i, use_short = 0;

	/* usage: [-s] [<bits>] */
	if (argc > 1 && strcmp(argv[1], "-s") == 0) {
	--argc;
	++argv;
	use_short = 1;
	}

	if (argc > 1) {
	bits_i = atoi(argv[1]);
	if (bits < 512) {
	fprintf(stderr, "Invalid RSA key size\n");
	return 1;
	}

	bits = (unsigned int)bits_i;
	}

	/* Avoid using key sizes less than 2048 bits; see comment at top of file. */
	if (bits < 2048)
	fprintf(stderr, "Warning: very weak key size\n\n");

	/* Generate RSA key. */
	if (use_short)
	pkey = generate_rsa_key_short(libctx, bits);
	else
	pkey = generate_rsa_key_long(libctx, bits);

	if (pkey == NULL)
	goto cleanup;

	/* Dump the integers comprising the key. */
	if (dump_key(pkey) == 0) {
	fprintf(stderr, "Failed to dump key\n");
	goto cleanup;
	}

	rv = 0;
	cleanup:
	EVP_PKEY_free(pkey);
	OSSL_LIB_CTX_free(libctx);
	return rv;
	}