122 lines
3.9 KiB
Groff
122 lines
3.9 KiB
Groff
.\" $OpenBSD: DH_generate_key.3,v 1.12 2019/08/19 13:08:26 schwarze Exp $
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.\" OpenSSL b97fdb57 Nov 11 09:33:09 2016 +0100
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.\"
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.\" This file was written by Ulf Moeller <ulf@openssl.org>.
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.\" Copyright (c) 2000 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: August 19 2019 $
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.Dt DH_GENERATE_KEY 3
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.Os
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.Sh NAME
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.Nm DH_generate_key ,
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.Nm DH_compute_key
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.Nd perform Diffie-Hellman key exchange
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.Sh SYNOPSIS
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.In openssl/dh.h
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.Ft int
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.Fo DH_generate_key
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.Fa "DH *dh"
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.Fc
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.Ft int
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.Fo DH_compute_key
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.Fa "unsigned char *key"
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.Fa "BIGNUM *pub_key"
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.Fa "DH *dh"
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.Fc
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.Sh DESCRIPTION
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.Fn DH_generate_key
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performs the first step of a Diffie-Hellman key exchange by generating
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private and public DH values.
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By calling
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.Fn DH_compute_key ,
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these are combined with the other party's public value to compute the
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shared key.
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.Pp
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.Fn DH_generate_key
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expects
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.Fa dh
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to contain the shared parameters
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.Sy dh->p
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and
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.Sy dh->g .
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It generates a random private DH value unless
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.Sy dh->priv_key
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is already set, and computes the corresponding public value
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.Sy dh->pub_key ,
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which can then be published.
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.Pp
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.Fn DH_compute_key
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computes the shared secret from the private DH value in
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.Fa dh
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and the other party's public value in
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.Fa pub_key
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and stores it in
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.Fa key .
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.Fa key
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must point to
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.Fn DH_size dh
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bytes of memory.
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.Sh RETURN VALUES
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.Fn DH_generate_key
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returns 1 on success, or 0 otherwise.
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.Pp
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.Fn DH_compute_key
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returns the size of the shared secret on success, or -1 on error.
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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 DH_get0_key 3 ,
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.Xr DH_new 3 ,
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.Xr DH_size 3 ,
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.Xr ECDH_compute_key 3
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.Sh HISTORY
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.Fn DH_generate_key
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and
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.Fn DH_compute_key
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first appeared in SSLeay 0.5.1 and have been available since
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.Ox 2.4 .
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