1.\" $OpenBSD: DH_new.3,v 1.12 2022/07/13 21:51:35 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 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: July 13 2022 $ 52.Dt DH_NEW 3 53.Os 54.Sh NAME 55.Nm DH_new , 56.Nm DH_up_ref , 57.Nm DH_free 58.Nd allocate and free DH objects 59.Sh SYNOPSIS 60.In openssl/dh.h 61.Ft DH* 62.Fn DH_new void 63.Ft int 64.Fo DH_up_ref 65.Fa "DH *dh" 66.Fc 67.Ft void 68.Fo DH_free 69.Fa "DH *dh" 70.Fc 71.Sh DESCRIPTION 72The DH functions implement the Diffie-Hellman key agreement protocol. 73.Pp 74.Fn DH_new 75allocates and initializes a 76.Vt DH 77structure, setting the reference count to 1. 78It is equivalent to 79.Xr DH_new_method 3 80with a 81.Dv NULL 82argument. 83.Pp 84.Fn DH_up_ref 85increments the reference count by 1. 86.Pp 87.Fn DH_free 88decrements the reference count by 1. 89If it reaches 0, it frees the 90.Vt DH 91structure and its components. 92The values are erased before the memory is returned to the system. 93If 94.Fa dh 95is a 96.Dv NULL 97pointer, no action occurs. 98.Sh RETURN VALUES 99If the allocation fails, 100.Fn DH_new 101returns 102.Dv NULL 103and sets an error code that can be obtained by 104.Xr ERR_get_error 3 . 105Otherwise it returns a pointer to the newly allocated structure. 106.Pp 107.Fn DH_up_ref 108returns 1 for success or 0 for failure. 109.Sh SEE ALSO 110.Xr BN_new 3 , 111.Xr crypto 3 , 112.Xr d2i_DHparams 3 , 113.Xr DH_generate_key 3 , 114.Xr DH_generate_parameters 3 , 115.Xr DH_get0_pqg 3 , 116.Xr DH_get_ex_new_index 3 , 117.Xr DH_security_bits 3 , 118.Xr DH_set_method 3 , 119.Xr DH_size 3 , 120.Xr DHparams_print 3 , 121.Xr DSA_dup_DH 3 , 122.Xr EVP_PKEY_CTX_set_dh_paramgen_prime_len 3 , 123.Xr EVP_PKEY_set1_DH 3 124.Sh HISTORY 125.Fn DH_new 126and 127.Fn DH_free 128first appeared in SSLeay 0.5.1 and have been available since 129.Ox 2.4 . 130.Pp 131.Fn DH_up_ref 132first appeared in OpenSSL 0.9.7 and has been available since 133.Ox 3.2 . 134