1.\" $OpenBSD: RSA_size.3,v 1.10 2022/07/13 21:51:35 schwarze Exp $ 2.\" full merge up to: OpenSSL 99d63d46 Oct 26 13:56:48 2016 -0400 3.\" 4.\" This file was written by Ulf Moeller <ulf@openssl.org> and 5.\" Kurt Roeckx <kurt@roeckx.be>. 6.\" Copyright (c) 2000, 2002, 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: July 13 2022 $ 53.Dt RSA_SIZE 3 54.Os 55.Sh NAME 56.Nm RSA_size , 57.Nm RSA_bits 58.Nd get the RSA modulus size 59.Sh SYNOPSIS 60.In openssl/rsa.h 61.Ft int 62.Fo RSA_size 63.Fa "const RSA *rsa" 64.Fc 65.Ft int 66.Fo RSA_bits 67.Fa "const RSA *rsa" 68.Fc 69.Sh DESCRIPTION 70.Fn RSA_size 71returns the RSA modulus size in bytes. 72It can be used to determine how much memory must be allocated for 73an RSA encrypted value. 74.Pp 75.Fn RSA_bits 76returns the number of significant bits. 77.Pp 78.Fa rsa 79and 80.Fa rsa->n 81must not be 82.Dv NULL . 83.Sh RETURN VALUES 84The size. 85.Sh SEE ALSO 86.Xr BN_num_bits 3 , 87.Xr RSA_get0_key 3 , 88.Xr RSA_new 3 , 89.Xr RSA_security_bits 3 90.Sh HISTORY 91.Fn RSA_size 92first appeared in SSLeay 0.4.4 and has been available since 93.Ox 2.4 . 94.Pp 95.Fn RSA_bits 96first appeared in OpenSSL 1.1.0 and has been available since 97.Ox 6.3 . 98