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			124 lines
		
	
	
		
			3.8 KiB
		
	
	
	
		
			Plaintext
		
	
	
	
			
		
		
	
	
			124 lines
		
	
	
		
			3.8 KiB
		
	
	
	
		
			Plaintext
		
	
	
	
=pod
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=head1 NAME
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EVP_RSA_gen,
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RSA_generate_key_ex, RSA_generate_key,
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RSA_generate_multi_prime_key - generate RSA key pair
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=head1 SYNOPSIS
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 #include <openssl/rsa.h>
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 EVP_PKEY *EVP_RSA_gen(unsigned int bits);
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Deprecated since OpenSSL 3.0, can be hidden entirely by defining
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B<OPENSSL_API_COMPAT> with a suitable version value, see
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L<openssl_user_macros(7)>:
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 int RSA_generate_key_ex(RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb);
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 int RSA_generate_multi_prime_key(RSA *rsa, int bits, int primes, BIGNUM *e, BN_GENCB *cb);
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Deprecated since OpenSSL 0.9.8:
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 RSA *RSA_generate_key(int bits, unsigned long e,
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                       void (*callback)(int, int, void *), void *cb_arg);
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=head1 DESCRIPTION
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EVP_RSA_gen() generates a new RSA key pair with modulus size I<bits>.
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All of the functions described below are deprecated.
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Applications should instead use EVP_RSA_gen(), L<EVP_PKEY_Q_keygen(3)>, or
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L<EVP_PKEY_keygen_init(3)> and L<EVP_PKEY_keygen(3)>.
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RSA_generate_key_ex() generates a 2-prime RSA key pair and stores it in the
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B<RSA> structure provided in I<rsa>.
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RSA_generate_multi_prime_key() generates a multi-prime RSA key pair and stores
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it in the B<RSA> structure provided in I<rsa>. The number of primes is given by
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the I<primes> parameter.
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If the automatic seeding or reseeding of the OpenSSL CSPRNG fails due to
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external circumstances (see L<RAND(7)>), the operation will fail.
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The modulus size will be of length I<bits>, the number of primes to form the
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modulus will be I<primes>, and the public exponent will be I<e>. Key sizes
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with I<num> E<lt> 1024 should be considered insecure. The exponent is an odd
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number, typically 3, 17 or 65537.
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In order to maintain adequate security level, the maximum number of permitted
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I<primes> depends on modulus bit length:
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   <1024 | >=1024 | >=4096 | >=8192
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   ------+--------+--------+-------
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     2   |   3    |   4    |   5
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A callback function may be used to provide feedback about the
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progress of the key generation. If I<cb> is not NULL, it
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will be called as follows using the BN_GENCB_call() function
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described on the L<BN_generate_prime(3)> page.
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RSA_generate_key() is similar to RSA_generate_key_ex() but
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expects an old-style callback function; see
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L<BN_generate_prime(3)> for information on the old-style callback.
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=over 2
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=item *
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While a random prime number is generated, it is called as
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described in L<BN_generate_prime(3)>.
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=item *
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When the n-th randomly generated prime is rejected as not
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suitable for the key, I<BN_GENCB_call(cb, 2, n)> is called.
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=item *
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When a random p has been found with p-1 relatively prime to I<e>,
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it is called as I<BN_GENCB_call(cb, 3, 0)>.
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=back
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The process is then repeated for prime q and other primes (if any)
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with I<BN_GENCB_call(cb, 3, i)> where I<i> indicates the i-th prime.
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=head1 RETURN VALUES
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EVP_RSA_gen() returns an I<EVP_PKEY> or NULL on failure.
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RSA_generate_multi_prime_key() returns 1 on success or 0 on error.
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RSA_generate_key_ex() returns 1 on success or 0 on error.
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The error codes can be obtained by L<ERR_get_error(3)>.
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RSA_generate_key() returns a pointer to the RSA structure or
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NULL if the key generation fails.
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=head1 BUGS
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I<BN_GENCB_call(cb, 2, x)> is used with two different meanings.
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=head1 SEE ALSO
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L<EVP_PKEY_Q_keygen(3)>
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L<BN_generate_prime(3)>, L<ERR_get_error(3)>,
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L<RAND_bytes(3)>, L<RAND(7)>
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=head1 HISTORY
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EVP_RSA_gen() was added in OpenSSL 3.0.
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All other functions described here were deprecated in OpenSSL 3.0.
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For replacement see L<EVP_PKEY-RSA(7)>.
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=head1 COPYRIGHT
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Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License").  You may not use
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this file except in compliance with the License.  You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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