1.\" $OpenBSD: DH_size.3,v 1.9 2018/03/27 17:35:50 schwarze Exp $ 2.\" full merge up to: OpenSSL b97fdb57 Nov 11 09:33:09 2016 +0100 3.\" 4.\" This file was written by Ulf Moeller <ulf@openssl.org> 5.\" and Kurt Roeckx <kurt@roeckx.be>. 6.\" Copyright (c) 2000, 2015 The OpenSSL Project. All rights reserved. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in 17.\" the documentation and/or other materials provided with the 18.\" distribution. 19.\" 20.\" 3. All advertising materials mentioning features or use of this 21.\" software must display the following acknowledgment: 22.\" "This product includes software developed by the OpenSSL Project 23.\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 24.\" 25.\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 26.\" endorse or promote products derived from this software without 27.\" prior written permission. For written permission, please contact 28.\" openssl-core@openssl.org. 29.\" 30.\" 5. Products derived from this software may not be called "OpenSSL" 31.\" nor may "OpenSSL" appear in their names without prior written 32.\" permission of the OpenSSL Project. 33.\" 34.\" 6. Redistributions of any form whatsoever must retain the following 35.\" acknowledgment: 36.\" "This product includes software developed by the OpenSSL Project 37.\" for use in the OpenSSL Toolkit (http://www.openssl.org/)" 38.\" 39.\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 40.\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 41.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 42.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 43.\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 44.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 45.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 46.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 47.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 48.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 49.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 50.\" OF THE POSSIBILITY OF SUCH DAMAGE. 51.\" 52.Dd $Mdocdate: March 27 2018 $ 53.Dt DH_SIZE 3 54.Os 55.Sh NAME 56.Nm DH_size , 57.Nm DH_bits 58.Nd get Diffie-Hellman prime size 59.Sh SYNOPSIS 60.In openssl/dh.h 61.Ft int 62.Fo DH_size 63.Fa "const DH *dh" 64.Fc 65.Ft int 66.Fo DH_bits 67.Fa "const DH *dh" 68.Fc 69.Sh DESCRIPTION 70.Fn DH_size 71returns the Diffie-Hellman prime size in bytes. 72It can be used to determine how much memory must be allocated for the 73shared secret computed by 74.Xr DH_compute_key 3 . 75.Pp 76.Fn DH_bits 77returns the number of significant bits in the key. 78.Pp 79.Fa dh 80and 81.Fa dh->p 82must not be 83.Dv NULL . 84.Sh SEE ALSO 85.Xr BN_num_bytes 3 , 86.Xr DH_generate_key 3 , 87.Xr DH_get0_key 3 , 88.Xr DH_new 3 89.Sh HISTORY 90.Fn DH_size 91first appeared in SSLeay 0.5.1 and has been available since 92.Ox 2.4 . 93.Pp 94.Fn DH_bits 95first appeared in OpenSSL 1.1.0 and has been available since 96.Ox 6.3 . 97