1.\" $OpenBSD: DSA_do_sign.3,v 1.5 2016/12/10 22:47:49 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: December 10 2016 $ 52.Dt DSA_DO_SIGN 3 53.Os 54.Sh NAME 55.Nm DSA_do_sign , 56.Nm DSA_do_verify 57.Nd raw DSA signature operations 58.Sh SYNOPSIS 59.In openssl/dsa.h 60.Ft DSA_SIG * 61.Fo DSA_do_sign 62.Fa "const unsigned char *dgst" 63.Fa "int dlen" 64.Fa "DSA *dsa" 65.Fc 66.Ft int 67.Fo DSA_do_verify 68.Fa "const unsigned char *dgst" 69.Fa "int dgst_len" 70.Fa "DSA_SIG *sig" 71.Fa "DSA *dsa" 72.Fc 73.Sh DESCRIPTION 74.Fn DSA_do_sign 75computes a digital signature on the 76.Fa dlen 77byte message digest 78.Fa dgst 79using the private key 80.Fa dsa 81and returns it in a newly allocated 82.Vt DSA_SIG 83structure. 84.Pp 85.Xr DSA_sign_setup 3 86may be used to precompute part of the signing operation in case 87signature generation is time-critical. 88.Pp 89.Fn DSA_do_verify 90verifies that the signature 91.Fa sig 92matches a given message digest 93.Fa dgst 94of size 95.Fa dgst_len . 96.Fa dsa 97is the signer's public key. 98.Sh RETURN VALUES 99.Fn DSA_do_sign 100returns the signature or 101.Dv NULL 102on error. 103.Fn DSA_do_verify 104returns 1 for a valid signature, 0 for an incorrect signature, 105and -1 on error. 106The error codes can be obtained by 107.Xr ERR_get_error 3 . 108.Sh SEE ALSO 109.Xr DSA_new 3 , 110.Xr DSA_SIG_new 3 , 111.Xr DSA_sign 3 , 112.Xr ERR_get_error 3 , 113.Xr RAND_bytes 3 114.Sh HISTORY 115.Fn DSA_do_sign 116and 117.Fn DSA_do_verify 118were added in OpenSSL 0.9.3. 119