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.\" $OpenBSD: EVP_PKEY_verify.3,v 1.7 2018/03/23 04:34:23 schwarze Exp $
.\" full merge up to: OpenSSL 48e5119a Jan 19 10:49:22 2018 +0100
.\"
.\" This file was written by Dr. Stephen Henson <steve@openssl.org>.
.\" Copyright (c) 2006, 2009, 2010, 2013, 2018 The OpenSSL Project.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\"
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\"
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in
.\" the documentation and/or other materials provided with the
.\" distribution.
.\"
.\" 3. All advertising materials mentioning features or use of this
.\" software must display the following acknowledgment:
.\" "This product includes software developed by the OpenSSL Project
.\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
.\"
.\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
.\" endorse or promote products derived from this software without
.\" prior written permission. For written permission, please contact
.\" openssl-core@openssl.org.
.\"
.\" 5. Products derived from this software may not be called "OpenSSL"
.\" nor may "OpenSSL" appear in their names without prior written
.\" permission of the OpenSSL Project.
.\"
.\" 6. Redistributions of any form whatsoever must retain the following
.\" acknowledgment:
.\" "This product includes software developed by the OpenSSL Project
.\" for use in the OpenSSL Toolkit (http://www.openssl.org/)"
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
.\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
.\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
.\" OF THE POSSIBILITY OF SUCH DAMAGE.
.\"
.Dd $Mdocdate: March 23 2018 $
.Dt EVP_PKEY_VERIFY 3
.Os
.Sh NAME
.Nm EVP_PKEY_verify_init ,
.Nm EVP_PKEY_verify
.Nd signature verification using a public key algorithm
.Sh SYNOPSIS
.In openssl/evp.h
.Ft int
.Fo EVP_PKEY_verify_init
.Fa "EVP_PKEY_CTX *ctx"
.Fc
.Ft int
.Fo EVP_PKEY_verify
.Fa "EVP_PKEY_CTX *ctx"
.Fa "const unsigned char *sig"
.Fa "size_t siglen"
.Fa "const unsigned char *tbs"
.Fa "size_t tbslen"
.Fc
.Sh DESCRIPTION
The
.Fn EVP_PKEY_verify_init
function initializes a public key algorithm context using key
.Fa ctx->pkey
for a signature verification operation.
.Pp
The
.Fn EVP_PKEY_verify
function performs a public key verification operation using
.Fa ctx .
The signature is specified using the
.Fa sig
and
.Fa siglen
parameters.
The verified data (i.e. the data believed originally signed) is
specified using the
.Fa tbs
and
.Fa tbslen
parameters.
.Pp
After the call to
.Fn EVP_PKEY_verify_init ,
algorithm specific control operations can be performed to set any
appropriate parameters for the operation.
.Pp
The function
.Fn EVP_PKEY_verify
can be called more than once on the same context if several operations
are performed using the same parameters.
.Sh RETURN VALUES
.Fn EVP_PKEY_verify_init
and
.Fn EVP_PKEY_verify
return 1 if the verification was successful and 0 if it failed.
Unlike other functions the return value 0 from
.Fn EVP_PKEY_verify
only indicates that the signature did not verify successfully.
That is,
.Fa tbs
did not match the original data or the signature was of invalid form.
It is not an indication of a more serious error.
.Pp
A negative value indicates an error other that signature verification
failure.
In particular, a return value of -2 indicates the operation is not
supported by the public key algorithm.
.Sh EXAMPLES
Verify signature using PKCS#1 and SHA256 digest:
.Bd -literal -offset 3n
#include <openssl/evp.h>
#include <openssl/rsa.h>
EVP_PKEY_CTX *ctx;
unsigned char *md, *sig;
size_t mdlen, siglen;
EVP_PKEY *verify_key;
/*
* Assumes that verify_key, sig, siglen, md, and mdlen are already set up
* and that verify_key is an RSA public key.
*/
ctx = EVP_PKEY_CTX_new(verify_key, NULL);
if (!ctx)
/* Error occurred */
if (EVP_PKEY_verify_init(ctx) <= 0)
/* Error */
if (EVP_PKEY_CTX_set_rsa_padding(ctx, RSA_PKCS1_PADDING) <= 0)
/* Error */
if (EVP_PKEY_CTX_set_signature_md(ctx, EVP_sha256()) <= 0)
/* Error */
/* Perform operation */
ret = EVP_PKEY_verify(ctx, sig, siglen, md, mdlen);
/*
* ret == 1 indicates success, 0 verify failure,
* and < 0 some other error.
*/
.Ed
.Sh SEE ALSO
.Xr EVP_PKEY_CTX_new 3 ,
.Xr EVP_PKEY_decrypt 3 ,
.Xr EVP_PKEY_derive 3 ,
.Xr EVP_PKEY_encrypt 3 ,
.Xr EVP_PKEY_meth_set_verify 3 ,
.Xr EVP_PKEY_sign 3 ,
.Xr EVP_PKEY_verify_recover 3
.Sh HISTORY
.Fn EVP_PKEY_verify_init
and
.Fn EVP_PKEY_verify
first appeared in OpenSSL 1.0.0 and have been available since
.Ox 4.9 .
|
