+++ /dev/null
-=pod
-
-=head1 NAME
-
-EVP_PKEY_verify_recover_init, EVP_PKEY_verify_recover - recover signature using a public key algorithm
-
-=head1 SYNOPSIS
-
- #include <openssl/evp.h>
-
- int EVP_PKEY_verify_recover_init(EVP_PKEY_CTX *ctx);
- int EVP_PKEY_verify_recover(EVP_PKEY_CTX *ctx,
- unsigned char *rout, size_t *routlen,
- const unsigned char *sig, size_t siglen);
-
-=head1 DESCRIPTION
-
-The EVP_PKEY_verify_recover_init() function initializes a public key algorithm
-context using key B<pkey> for a verify recover operation.
-
-The EVP_PKEY_verify_recover() function recovers signed data
-using B<ctx>. The signature is specified using the B<sig> and
-B<siglen> parameters. If B<rout> is B<NULL> then the maximum size of the output
-buffer is written to the B<routlen> parameter. If B<rout> is not B<NULL> then
-before the call the B<routlen> parameter should contain the length of the
-B<rout> buffer, if the call is successful recovered data is written to
-B<rout> and the amount of data written to B<routlen>.
-
-=head1 NOTES
-
-Normally an application is only interested in whether a signature verification
-operation is successful in those cases the EVP_verify() function should be
-used.
-
-Sometimes however it is useful to obtain the data originally signed using a
-signing operation. Only certain public key algorithms can recover a signature
-in this way (for example RSA in PKCS padding mode).
-
-After the call to EVP_PKEY_verify_recover_init() algorithm specific control
-operations can be performed to set any appropriate parameters for the
-operation.
-
-The function EVP_PKEY_verify_recover() 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_recover_init() and EVP_PKEY_verify_recover() return 1 for success
-and 0 or a negative value for failure. In particular a return value of -2
-indicates the operation is not supported by the public key algorithm.
-
-=head1 EXAMPLE
-
-Recover digest originally signed using PKCS#1 and SHA256 digest:
-
- #include <openssl/evp.h>
- #include <openssl/rsa.h>
-
- EVP_PKEY_CTX *ctx;
- unsigned char *rout, *sig;
- size_t routlen, siglen;
- EVP_PKEY *verify_key;
- /* NB: assumes verify_key, sig and siglen are already set up
- * and that verify_key is an RSA public key
- */
- ctx = EVP_PKEY_CTX_new(verify_key);
- if (!ctx)
- /* Error occurred */
- if (EVP_PKEY_verify_recover_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 */
-
- /* Determine buffer length */
- if (EVP_PKEY_verify_recover(ctx, NULL, &routlen, sig, siglen) <= 0)
- /* Error */
-
- rout = OPENSSL_malloc(routlen);
-
- if (!rout)
- /* malloc failure */
-
- if (EVP_PKEY_verify_recover(ctx, rout, &routlen, sig, siglen) <= 0)
- /* Error */
-
- /* Recovered data is routlen bytes written to buffer rout */
-
-=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(3)>,
-L<EVP_PKEY_derive(3)>
-
-=head1 HISTORY
-
-These functions were first added to OpenSSL 1.0.0.
-
-=head1 COPYRIGHT
-
-Copyright 2013-2016 The OpenSSL Project Authors. All Rights Reserved.
-
-Licensed under the OpenSSL license (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
projects / openssl.git / blobdiff