1.\" $OpenBSD: RSA_generate_key.3,v 1.13 2019/06/10 14:58:48 schwarze Exp $ 2.\" OpenSSL RSA_generate_key.pod bb6c5e7f Feb 5 10:29:22 2017 -0500 3.\" 4.\" This file was written by Ulf Moeller <ulf@openssl.org>. 5.\" Copyright (c) 2000, 2002, 2013 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. 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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 RSA_GENERATE_KEY 3 53.Os 54.Sh NAME 55.Nm RSA_generate_key_ex , 56.Nm RSA_generate_key 57.Nd generate RSA key pair 58.Sh SYNOPSIS 59.In openssl/rsa.h 60.Ft int 61.Fo RSA_generate_key_ex 62.Fa "RSA *rsa" 63.Fa "int bits" 64.Fa "BIGNUM *e" 65.Fa "BN_GENCB *cb" 66.Fc 67.Pp 68Deprecated: 69.Pp 70.Ft RSA * 71.Fo RSA_generate_key 72.Fa "int num" 73.Fa "unsigned long e" 74.Fa "void (*callback)(int, int, void *)" 75.Fa "void *cb_arg" 76.Fc 77.Sh DESCRIPTION 78.Fn RSA_generate_key_ex 79generates a key pair and stores it in 80.Fa rsa . 81.Pp 82The modulus size will be of length 83.Fa bits , 84and the public exponent will be 85.Fa e . 86Key sizes with 87.Fa num 88< 1024 should be considered insecure. 89The exponent is an odd number, typically 3, 17 or 65537. 90.Pp 91A callback function may be used to provide feedback about the progress 92of the key generation. 93If 94.Fa cb 95is not 96.Dv NULL , 97it will be called as follows using the 98.Xr BN_GENCB_call 3 99function: 100.Bl -bullet 101.It 102While a random prime number is generated, it is called as described in 103.Xr BN_generate_prime 3 . 104.It 105When the 106.Fa n Ns -th 107randomly generated prime is rejected as not suitable for 108the key, 109.Fn BN_GENCB_call cb 2 n 110is called. 111.It 112When a random p has been found with p-1 relatively prime to 113.Fa e , 114it is called as 115.Fn BN_GENCB_call cb 3 0 . 116.El 117.Pp 118The process is then repeated for prime q with 119.Fn BN_GENCB_call cb 3 1 . 120.Pp 121.Fn RSA_generate_key 122is deprecated. 123New applications should use 124.Fn RSA_generate_key_ex 125instead. 126.Fn RSA_generate_key 127works in the same way as 128.Fn RSA_generate_key_ex 129except it uses "old style" call backs. 130See 131.Xr BN_generate_prime 3 132for further details. 133.Sh RETURN VALUES 134.Fn RSA_generate_key_ex 135returns 1 on success or 0 on error. 136.Fn RSA_generate_key 137returns the key on success or 138.Dv NULL 139on error. 140.Pp 141The error codes can be obtained by 142.Xr ERR_get_error 3 . 143.Sh SEE ALSO 144.Xr BN_generate_prime 3 , 145.Xr RSA_get0_key 3 , 146.Xr RSA_meth_set_keygen 3 , 147.Xr RSA_new 3 148.Sh HISTORY 149.Fn RSA_generate_key 150appeared in SSLeay 0.4 or earlier and had its 151.Fa cb_arg 152argument added in SSLeay 0.9.0. 153It has been available since 154.Ox 2.4 . 155.Pp 156.Fn RSA_generate_key_ex 157first appeared in OpenSSL 0.9.8 and has been available since 158.Ox 4.5 . 159.Sh BUGS 160.Fn BN_GENCB_call cb 2 x 161is used with two different meanings. 162.Pp 163.Fn RSA_generate_key 164goes into an infinite loop for illegal input values. 165