RSA_generate_key(3) - NetBSD Manual Pages

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RSA_generate_key(3)                 OpenSSL                RSA_generate_key(3)




NAME

       EVP_RSA_gen, RSA_generate_key_ex, RSA_generate_key,
       RSA_generate_multi_prime_key - generate RSA key pair


SYNOPSIS

        #include <openssl/rsa.h>

        EVP_PKEY *EVP_RSA_gen(unsigned int bits);

       The following functions have been deprecated since OpenSSL 3.0, and can
       be hidden entirely by defining OPENSSL_API_COMPAT with a suitable
       version value, see openssl_user_macros(7):

        int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb);
        int RSA_generate_multi_prime_key(RSA *rsa, int bits, int primes, BIGNUM *e, BN_GENCB *cb);

       The following function has been deprecated since OpenSSL 0.9.8, and can
       be hidden entirely by defining OPENSSL_API_COMPAT with a suitable
       version value, see openssl_user_macros(7):

        RSA *RSA_generate_key(int bits, unsigned long e,
                              void (*callback)(int, int, void *), void *cb_arg);


DESCRIPTION

       EVP_RSA_gen() generates a new RSA key pair with modulus size bits.

       All of the functions described below are deprecated.  Applications
       should instead use EVP_RSA_gen(), EVP_PKEY_Q_keygen(3), or
       EVP_PKEY_keygen_init(3) and EVP_PKEY_keygen(3).

       RSA_generate_key_ex() generates a 2-prime RSA key pair and stores it in
       the RSA structure provided in rsa.

       RSA_generate_multi_prime_key() generates a multi-prime RSA key pair and
       stores it in the RSA structure provided in rsa. The number of primes is
       given by the primes parameter.  If the automatic seeding or reseeding
       of the OpenSSL CSPRNG fails due to external circumstances (see
       RAND(7)), the operation will fail.

       The modulus size will be of length bits, the number of primes to form
       the modulus will be primes, and the public exponent will be e. Key
       sizes with num < 1024 should be considered insecure. The exponent is an
       odd number, typically 3, 17 or 65537.

       In order to maintain adequate security level, the maximum number of
       permitted primes depends on modulus bit length:

          <1024 | >=1024 | >=4096 | >=8192
          ------+--------+--------+-------
            2   |   3    |   4    |   5

       A callback function may be used to provide feedback about the progress
       of the key generation. If cb is not NULL, it will be called as follows
       using the BN_GENCB_call() function described on the
       BN_generate_prime(3) page.

       RSA_generate_key() is similar to RSA_generate_key_ex() but expects an
       old-style callback function; see BN_generate_prime(3) for information
       on the old-style callback.

       · While a random prime number is generated, it is called as described
         in BN_generate_prime(3).

       · When the n-th randomly generated prime is rejected as not suitable
         for the key, BN_GENCB_call(cb, 2, n) is called.

       · When a random p has been found with p-1 relatively prime to e, it is
         called as BN_GENCB_call(cb, 3, 0).

       The process is then repeated for prime q and other primes (if any) with
       BN_GENCB_call(cb, 3, i) where i indicates the i-th prime.


RETURN VALUES

       EVP_RSA_gen() returns an EVP_PKEY or NULL on failure.

       RSA_generate_multi_prime_key() returns 1 on success or 0 on error.
       RSA_generate_key_ex() returns 1 on success or 0 on error.  The error
       codes can be obtained by ERR_get_error(3).

       RSA_generate_key() returns a pointer to the RSA structure or NULL if
       the key generation fails.


BUGS

       BN_GENCB_call(cb, 2, x) is used with two different meanings.


SEE ALSO

       EVP_PKEY_Q_keygen(3) BN_generate_prime(3), ERR_get_error(3),
       RAND_bytes(3), RAND(7)


HISTORY

       EVP_RSA_gen() was added in OpenSSL 3.0.  All other functions described
       here were deprecated in OpenSSL 3.0.  For replacement see
       EVP_PKEY-RSA(7).


COPYRIGHT

       Copyright 2000-2021 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>.



3.0.15                            2024-09-03               RSA_generate_key(3)