1.\" $OpenBSD: DSA_dup_DH.3,v 1.8 2019/06/10 14:58:48 schwarze Exp $ 2.\" OpenSSL b97fdb57 Nov 11 09:33:09 2016 +0100 3.\" 4.\" This file was written by Ulf Moeller <ulf@openssl.org>. 5.\" Copyright (c) 2000, 2002 The OpenSSL Project. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in 16.\" the documentation and/or other materials provided with the 17.\" distribution. 18.\" 19.\" 3. All advertising materials mentioning features or use of this 20.\" software must display the following acknowledgment: 21.\" "This product includes software developed by the OpenSSL Project 22.\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 23.\" 24.\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 25.\" endorse or promote products derived from this software without 26.\" prior written permission. For written permission, please contact 27.\" openssl-core@openssl.org. 28.\" 29.\" 5. Products derived from this software may not be called "OpenSSL" 30.\" nor may "OpenSSL" appear in their names without prior written 31.\" permission of the OpenSSL Project. 32.\" 33.\" 6. Redistributions of any form whatsoever must retain the following 34.\" acknowledgment: 35.\" "This product includes software developed by the OpenSSL Project 36.\" for use in the OpenSSL Toolkit (http://www.openssl.org/)" 37.\" 38.\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 39.\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 40.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 41.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 42.\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 43.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 44.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 45.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 46.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 47.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 48.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 49.\" OF THE POSSIBILITY OF SUCH DAMAGE. 50.\" 51.Dd $Mdocdate: June 10 2019 $ 52.Dt DSA_DUP_DH 3 53.Os 54.Sh NAME 55.Nm DSA_dup_DH 56.Nd create a DH structure out of DSA structure 57.Sh SYNOPSIS 58.In openssl/dsa.h 59.Ft DH * 60.Fo DSA_dup_DH 61.Fa "const DSA *r" 62.Fc 63.Sh DESCRIPTION 64.Fn DSA_dup_DH 65duplicates 66.Vt DSA 67parameters/keys as 68.Vt DH 69parameters/keys. 70.Fa r->q 71is lost during that conversion, but the resulting 72.Vt DH 73parameters contain its length. 74.Sh RETURN VALUES 75.Fn DSA_dup_DH 76returns the new 77.Vt DH 78structure or 79.Dv NULL 80on error. 81The error codes can be obtained by 82.Xr ERR_get_error 3 . 83.Sh SEE ALSO 84.Xr DH_new 3 , 85.Xr DSA_get0_pqg 3 , 86.Xr DSA_new 3 87.Sh HISTORY 88.Fn DSA_dup_DH 89first appeared in OpenSSL 0.9.4 and has been available since 90.Ox 2.6 . 91.Sh CAVEATS 92Be careful to avoid small subgroup attacks when using this. 93