openssl/doc/man3/EVP_PKEY_verify.pod
Dr. Matthias St. Pierre fc5ecaddd0 man: harmonize the various formulations in the HISTORY sections
While stereotyped repetitions are frowned upon in literature, they
serve a useful purpose in manual pages, because it is easier for
the user to find certain information if it is always presented in
the same way. For that reason, this commit harmonizes the varying
formulations in the HISTORY section about which functions, flags,
etc. were added in which OpenSSL version.

It also attempts to make the pod files more grep friendly by
avoiding to insert line breaks between the symbol names and the
corresponding version number in which they were introduced
(wherever possible). Some punctuation and typographical errors
were fixed on the way.

Reviewed-by: Tim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7854)
2018-12-15 22:27:26 +01:00

104 lines
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=pod
=head1 NAME
EVP_PKEY_verify_init, EVP_PKEY_verify - signature verification using a public key algorithm
=head1 SYNOPSIS
#include <openssl/evp.h>
int EVP_PKEY_verify_init(EVP_PKEY_CTX *ctx);
int EVP_PKEY_verify(EVP_PKEY_CTX *ctx,
const unsigned char *sig, size_t siglen,
const unsigned char *tbs, size_t tbslen);
=head1 DESCRIPTION
The EVP_PKEY_verify_init() function initializes a public key algorithm
context using key B<pkey> for a signature verification operation.
The EVP_PKEY_verify() function performs a public key verification operation
using B<ctx>. The signature is specified using the B<sig> and
B<siglen> parameters. The verified data (i.e. the data believed originally
signed) is specified using the B<tbs> and B<tbslen> parameters.
=head1 NOTES
After the call to EVP_PKEY_verify_init() algorithm specific control
operations can be performed to set any appropriate parameters for the
operation.
The function EVP_PKEY_verify() can be called more than once on the same
context if several operations are performed using the same parameters.
=head1 RETURN VALUES
EVP_PKEY_verify_init() and EVP_PKEY_verify() return 1 if the verification was
successful and 0 if it failed. Unlike other functions the return value 0 from
EVP_PKEY_verify() only indicates that the signature did not verify
successfully (that is tbs did not match the original data or the signature was
of invalid form) it is not an indication of a more serious error.
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.
=head1 EXAMPLE
Verify signature using PKCS#1 and SHA256 digest:
#include <openssl/evp.h>
#include <openssl/rsa.h>
EVP_PKEY_CTX *ctx;
unsigned char *md, *sig;
size_t mdlen, siglen;
EVP_PKEY *verify_key;
/*
* NB: assumes 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 /* no engine */);
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 for some
* other error.
*/
=head1 SEE ALSO
L<EVP_PKEY_CTX_new(3)>,
L<EVP_PKEY_encrypt(3)>,
L<EVP_PKEY_decrypt(3)>,
L<EVP_PKEY_sign(3)>,
L<EVP_PKEY_verify_recover(3)>,
L<EVP_PKEY_derive(3)>
=head1 HISTORY
These functions were added in OpenSSL 1.0.0.
=head1 COPYRIGHT
Copyright 2006-2018 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
L<https://www.openssl.org/source/license.html>.
=cut