| 1 | =pod
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| 2 |
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| 3 | =head1 NAME
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| 4 |
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| 5 | EVP_RSA_gen,
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| 6 | RSA_generate_key_ex, RSA_generate_key,
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| 7 | RSA_generate_multi_prime_key - generate RSA key pair
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| 8 |
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| 9 | =head1 SYNOPSIS
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| 10 |
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| 11 | #include <openssl/rsa.h>
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| 12 |
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| 13 | EVP_PKEY *EVP_RSA_gen(unsigned int bits);
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| 14 |
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| 15 | The following functions have been deprecated since OpenSSL 3.0, and can be
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| 16 | hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value,
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| 17 | see L<openssl_user_macros(7)>:
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| 18 |
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| 19 | int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb);
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| 20 | int RSA_generate_multi_prime_key(RSA *rsa, int bits, int primes, BIGNUM *e, BN_GENCB *cb);
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| 21 |
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| 22 | The following function has been deprecated since OpenSSL 0.9.8, and can be
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| 23 | hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value,
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| 24 | see L<openssl_user_macros(7)>:
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| 25 |
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| 26 | RSA *RSA_generate_key(int bits, unsigned long e,
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| 27 | void (*callback)(int, int, void *), void *cb_arg);
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| 28 |
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| 29 | =head1 DESCRIPTION
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| 30 |
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| 31 | EVP_RSA_gen() generates a new RSA key pair with modulus size I<bits>.
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| 32 |
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| 33 | All of the functions described below are deprecated.
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| 34 | Applications should instead use EVP_RSA_gen(), L<EVP_PKEY_Q_keygen(3)>, or
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| 35 | L<EVP_PKEY_keygen_init(3)> and L<EVP_PKEY_keygen(3)>.
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| 36 |
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| 37 | RSA_generate_key_ex() generates a 2-prime RSA key pair and stores it in the
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| 38 | B<RSA> structure provided in I<rsa>.
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| 39 |
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| 40 | RSA_generate_multi_prime_key() generates a multi-prime RSA key pair and stores
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| 41 | it in the B<RSA> structure provided in I<rsa>. The number of primes is given by
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| 42 | the I<primes> parameter.
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| 43 | If the automatic seeding or reseeding of the OpenSSL CSPRNG fails due to
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| 44 | external circumstances (see L<RAND(7)>), the operation will fail.
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| 45 |
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| 46 | The modulus size will be of length I<bits>, the number of primes to form the
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| 47 | modulus will be I<primes>, and the public exponent will be I<e>. Key sizes
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| 48 | with I<num> E<lt> 1024 should be considered insecure. The exponent is an odd
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| 49 | number, typically 3, 17 or 65537.
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| 50 |
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| 51 | In order to maintain adequate security level, the maximum number of permitted
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| 52 | I<primes> depends on modulus bit length:
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| 53 |
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| 54 | <1024 | >=1024 | >=4096 | >=8192
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| 55 | ------+--------+--------+-------
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| 56 | 2 | 3 | 4 | 5
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| 57 |
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| 58 | A callback function may be used to provide feedback about the
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| 59 | progress of the key generation. If I<cb> is not NULL, it
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| 60 | will be called as follows using the BN_GENCB_call() function
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| 61 | described on the L<BN_generate_prime(3)> page.
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| 62 |
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| 63 | RSA_generate_key() is similar to RSA_generate_key_ex() but
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| 64 | expects an old-style callback function; see
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| 65 | L<BN_generate_prime(3)> for information on the old-style callback.
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| 66 |
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| 67 | =over 2
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| 68 |
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| 69 | =item *
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| 70 |
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| 71 | While a random prime number is generated, it is called as
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| 72 | described in L<BN_generate_prime(3)>.
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| 73 |
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| 74 | =item *
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| 75 |
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| 76 | When the n-th randomly generated prime is rejected as not
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| 77 | suitable for the key, I<BN_GENCB_call(cb, 2, n)> is called.
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| 78 |
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| 79 | =item *
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| 80 |
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| 81 | When a random p has been found with p-1 relatively prime to I<e>,
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| 82 | it is called as I<BN_GENCB_call(cb, 3, 0)>.
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| 83 |
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| 84 | =back
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| 85 |
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| 86 | The process is then repeated for prime q and other primes (if any)
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| 87 | with I<BN_GENCB_call(cb, 3, i)> where I<i> indicates the i-th prime.
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| 88 |
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| 89 | =head1 RETURN VALUES
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| 90 |
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| 91 | EVP_RSA_gen() returns an I<EVP_PKEY> or NULL on failure.
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| 92 |
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| 93 | RSA_generate_multi_prime_key() returns 1 on success or 0 on error.
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| 94 | RSA_generate_key_ex() returns 1 on success or 0 on error.
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| 95 | The error codes can be obtained by L<ERR_get_error(3)>.
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| 96 |
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| 97 | RSA_generate_key() returns a pointer to the RSA structure or
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| 98 | NULL if the key generation fails.
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| 99 |
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| 100 | =head1 BUGS
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| 101 |
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| 102 | I<BN_GENCB_call(cb, 2, x)> is used with two different meanings.
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| 103 |
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| 104 | =head1 SEE ALSO
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| 105 |
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| 106 | L<EVP_PKEY_Q_keygen(3)>
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| 107 | L<BN_generate_prime(3)>, L<ERR_get_error(3)>,
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| 108 | L<RAND_bytes(3)>, L<RAND(7)>
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| 109 |
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| 110 | =head1 HISTORY
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| 111 |
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| 112 | EVP_RSA_gen() was added in OpenSSL 3.0.
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| 113 | All other functions described here were deprecated in OpenSSL 3.0.
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| 114 | For replacement see L<EVP_PKEY-RSA(7)>.
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| 115 |
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| 116 | =head1 COPYRIGHT
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| 117 |
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| 118 | Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
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| 119 |
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| 120 | Licensed under the Apache License 2.0 (the "License"). You may not use
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| 121 | this file except in compliance with the License. You can obtain a copy
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| 122 | in the file LICENSE in the source distribution or at
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| 123 | L<https://www.openssl.org/source/license.html>.
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| 124 |
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| 125 | =cut
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