EVP_RSA_gen, RSA_generate_key_ex, RSA_generate_key, RSA_generate_multi_prime_key
- generate RSA key pair
#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);
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.
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.
BN_GENCB_call(cb, 2, x) is used with two different meanings.
EVP_PKEY_Q_keygen(3) BN_generate_prime(3),
ERR_get_error(3),
RAND_bytes(3),
RAND(7)
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 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>.