1.\" $OpenBSD: RSA_sign.3,v 1.8 2019/06/10 14:58:48 schwarze Exp $ 2.\" OpenSSL aa90ca11 Aug 20 15:48:56 2016 -0400 3.\" 4.\" This file was written by Ulf Moeller <ulf@openssl.org>. 5.\" Copyright (c) 2000, 2005, 2014, 2015, 2016 The OpenSSL Project. 6.\" 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: June 10 2019 $ 53.Dt RSA_SIGN 3 54.Os 55.Sh NAME 56.Nm RSA_sign , 57.Nm RSA_verify 58.Nd RSA signatures 59.Sh SYNOPSIS 60.In openssl/rsa.h 61.Ft int 62.Fo RSA_sign 63.Fa "int type" 64.Fa "const unsigned char *m" 65.Fa "unsigned int m_len" 66.Fa "unsigned char *sigret" 67.Fa "unsigned int *siglen" 68.Fa "RSA *rsa" 69.Fc 70.Ft int 71.Fo RSA_verify 72.Fa "int type" 73.Fa "const unsigned char *m" 74.Fa "unsigned int m_len" 75.Fa "unsigned char *sigbuf" 76.Fa "unsigned int siglen" 77.Fa "RSA *rsa" 78.Fc 79.Sh DESCRIPTION 80.Fn RSA_sign 81signs the message digest 82.Fa m 83of size 84.Fa m_len 85using the private key 86.Fa rsa 87using RSASSA-PKCS1-v1_5 as specified in RFC 3447. 88It stores the signature in 89.Fa sigret 90and the signature size in 91.Fa siglen . 92.Fa sigret 93must point to 94.Fn RSA_size rsa 95bytes of memory. 96Note that PKCS #1 adds meta-data, placing limits on the size of the key 97that can be used. 98See 99.Xr RSA_private_encrypt 3 100for lower-level operations. 101.Pp 102.Fa type 103denotes the message digest algorithm that was used to generate 104.Fa m . 105If 106.Fa type 107is 108.Sy NID_md5_sha1 , 109an SSL signature (MD5 and SHA1 message digests with PKCS #1 padding and 110no algorithm identifier) is created. 111.Pp 112.Fn RSA_verify 113verifies that the signature 114.Fa sigbuf 115of size 116.Fa siglen 117matches a given message digest 118.Fa m 119of size 120.Fa m_len . 121.Fa type 122denotes the message digest algorithm that was used to generate the 123signature. 124.Fa rsa 125is the signer's public key. 126.Sh RETURN VALUES 127.Fn RSA_sign 128returns 1 on success. 129.Fn RSA_verify 130returns 1 on successful verification. 131.Pp 132The error codes can be obtained by 133.Xr ERR_get_error 3 . 134.Sh SEE ALSO 135.Xr RSA_meth_set_sign 3 , 136.Xr RSA_new 3 , 137.Xr RSA_private_encrypt 3 , 138.Xr RSA_public_decrypt 3 139.Sh STANDARDS 140SSL, PKCS #1 v2.0 141.Sh HISTORY 142.Fn RSA_sign 143first appeared in SSLeay 0.4.4. 144.Fn RSA_verify 145first appeared in SSLeay 0.6.0. 146Both functions have been available since 147.Ox 2.4 . 148