226 lines
6.5 KiB
Groff
226 lines
6.5 KiB
Groff
.\" $OpenBSD: DSA_generate_parameters.3,v 1.12 2019/06/10 14:58:48 schwarze Exp $
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.\" OpenSSL 9b86974e Aug 7 22:14:47 2015 -0400
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.\"
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.\" This file was written by Ulf Moeller <ulf@openssl.org>,
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.\" Bodo Moeller <bodo@openssl.org>, and Matt Caswell <matt@openssl.org>.
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.\" Copyright (c) 2000, 2013 The OpenSSL Project. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\"
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\"
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in
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.\" the documentation and/or other materials provided with the
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.\" distribution.
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.\"
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.\" 3. All advertising materials mentioning features or use of this
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.\" software must display the following acknowledgment:
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.\" "This product includes software developed by the OpenSSL Project
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.\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
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.\"
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.\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
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.\" endorse or promote products derived from this software without
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.\" prior written permission. For written permission, please contact
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.\" openssl-core@openssl.org.
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.\"
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.\" 5. Products derived from this software may not be called "OpenSSL"
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.\" nor may "OpenSSL" appear in their names without prior written
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.\" permission of the OpenSSL Project.
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.\"
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.\" 6. Redistributions of any form whatsoever must retain the following
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.\" acknowledgment:
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.\" "This product includes software developed by the OpenSSL Project
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.\" for use in the OpenSSL Toolkit (http://www.openssl.org/)"
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
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.\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
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.\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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.\" OF THE POSSIBILITY OF SUCH DAMAGE.
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.\"
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.Dd $Mdocdate: June 10 2019 $
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.Dt DSA_GENERATE_PARAMETERS 3
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.Os
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.Sh NAME
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.Nm DSA_generate_parameters_ex ,
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.Nm DSA_generate_parameters
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.Nd generate DSA parameters
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.Sh SYNOPSIS
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.In openssl/dsa.h
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.Ft int
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.Fo DSA_generate_parameters_ex
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.Fa "DSA *dsa"
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.Fa "int bits"
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.Fa "const unsigned char *seed"
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.Fa "int seed_len"
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.Fa "int *counter_ret"
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.Fa "unsigned long *h_ret"
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.Fa "BN_GENCB *cb"
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.Fc
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.Pp
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Deprecated:
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.Pp
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.Ft DSA *
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.Fo DSA_generate_parameters
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.Fa "int bits"
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.Fa "unsigned char *seed"
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.Fa "int seed_len"
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.Fa "int *counter_ret"
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.Fa "unsigned long *h_ret"
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.Fa "void (*callback)(int, int, void *)"
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.Fa "void *cb_arg"
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.Fc
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.Sh DESCRIPTION
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.Fn DSA_generate_parameters_ex
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generates primes p and q and a generator g for use in the DSA and stores
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the result in
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.Fa dsa .
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.Pp
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.Fa bits
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is the length of the prime to be generated; the DSS allows a maximum of
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1024 bits.
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.Pp
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If
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.Fa seed
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is
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.Dv NULL
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or
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.Fa seed_len
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< 20, the primes will be generated at random.
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Otherwise, the seed is used to generate them.
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If the given seed does not yield a prime q, a new random seed is chosen
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and placed at
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.Fa seed .
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.Pp
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.Fn DSA_generate_parameters_ex
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places the iteration count in
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.Pf * Fa counter_ret
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and a counter used for finding a generator in
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.Pf * Fa h_ret ,
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unless these are
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.Dv NULL .
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.Pp
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A callback function may be used to provide feedback about the progress
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of the key generation.
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If
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.Fa cb
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is not
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.Dv NULL ,
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it will be called as shown below.
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For information on the
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.Vt BN_GENCB
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structure, refer to
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.Xr BN_GENCB_call 3 .
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.Bl -bullet
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.It
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When a candidate for q is generated,
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.Fn BN_GENCB_call cb 0 m++
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is called
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.Pf ( Fa m
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is 0 for the first candidate).
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.It
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When a candidate for q has passed a test by trial division,
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.Fn BN_GENCB_call cb 1 -1
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is called.
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While a candidate for q is tested by Miller-Rabin primality tests,
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.Fn BN_GENCB_call cb 1 i
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is called in the outer loop (once for each witness that confirms that
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the candidate may be prime);
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.Fa i
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is the loop counter (starting at 0).
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.It
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When a prime q has been found,
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.Fn BN_GENCB_call cb 2 0
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and
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.Fn BN_GENCB_call cb 3 0
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are called.
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.It
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Before a candidate for p (other than the first) is generated and tested,
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.Fn BN_GENCB_call cb 0 counter
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is called.
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.It
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When a candidate for p has passed the test by trial division,
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.Fn BN_GENCB_call cb 1 -1
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is called.
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While it is tested by the Miller-Rabin primality test,
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.Fn BN_GENCB_call cb 1 i
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is called in the outer loop (once for each witness that confirms that
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the candidate may be prime).
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.Fa i
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is the loop counter (starting at 0).
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.It
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When p has been found,
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.Fn BN_GENCB_call cb 2 1
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is called.
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.It
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When the generator has been found,
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.Fn BN_GENCB_call cb 3 1
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is called.
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.El
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.Pp
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.Fn DSA_generate_parameters
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(deprecated) works in much the same way as for
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.Fn DSA_generate_parameters_ex ,
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except that no
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.Fa dsa
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parameter is passed and instead a newly allocated
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.Vt DSA
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structure is returned.
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Additionally "old style" callbacks are used instead of the newer
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.Vt BN_GENCB
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based approach.
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Refer to
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.Xr BN_generate_prime 3
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for further information.
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.Sh RETURN VALUES
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.Fn DSA_generate_parameters_ex
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returns a 1 on success, or 0 otherwise.
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.Pp
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.Fn DSA_generate_parameters
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returns a pointer to the
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.Vt DSA
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structure, or
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.Dv NULL
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if the parameter generation fails.
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.Pp
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The error codes can be obtained by
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.Xr ERR_get_error 3 .
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.Sh SEE ALSO
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.Xr BN_generate_prime 3 ,
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.Xr DSA_get0_pqg 3 ,
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.Xr DSA_new 3
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.Sh HISTORY
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.Fn DSA_generate_parameters
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first appeared in SSLeay 0.8.0 and had its
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.Fa cb_arg
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argument added in SSLeay 0.9.0.
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It has been available since
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.Ox 2.4 .
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.Pp
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In versions up to OpenSSL 0.9.4,
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.Fn callback 1 ...\&
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was called in the inner loop of the Miller-Rabin test whenever it
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reached the squaring step (the parameters to
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.Fn callback
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did not reveal how many witnesses had been tested); since OpenSSL 0.9.5,
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.Fn callback 1 ...\&
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is called as in
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.Xr BN_is_prime 3 ,
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i.e. once for each witness.
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.Pp
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.Fn DSA_generate_parameters_ex
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first appeared in OpenSSL 0.9.8 and has been available since
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.Ox 4.5 .
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.Sh BUGS
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Seed lengths > 20 are not supported.
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