mirror of https://github.com/openssl/openssl.git
103 lines
2.8 KiB
Plaintext
103 lines
2.8 KiB
Plaintext
=pod
|
|
|
|
=head1 NAME
|
|
|
|
EVP_PKEY_derive_init, EVP_PKEY_derive_set_peer, EVP_PKEY_derive - derive public key algorithm shared secret
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/evp.h>
|
|
|
|
int EVP_PKEY_derive_init(EVP_PKEY_CTX *ctx);
|
|
int EVP_PKEY_derive_set_peer(EVP_PKEY_CTX *ctx, EVP_PKEY *peer);
|
|
int EVP_PKEY_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
The EVP_PKEY_derive_init() function initializes a public key algorithm
|
|
context using key B<pkey> for shared secret derivation.
|
|
|
|
The EVP_PKEY_derive_set_peer() function sets the peer key: this will normally
|
|
be a public key.
|
|
|
|
The EVP_PKEY_derive() derives a shared secret using B<ctx>.
|
|
If B<key> is B<NULL> then the maximum size of the output buffer is written to
|
|
the B<keylen> parameter. If B<key> is not B<NULL> then before the call the
|
|
B<keylen> parameter should contain the length of the B<key> buffer, if the call
|
|
is successful the shared secret is written to B<key> and the amount of data
|
|
written to B<keylen>.
|
|
|
|
=head1 NOTES
|
|
|
|
After the call to EVP_PKEY_derive_init() algorithm specific control
|
|
operations can be performed to set any appropriate parameters for the
|
|
operation.
|
|
|
|
The function EVP_PKEY_derive() can be called more than once on the same
|
|
context if several operations are performed using the same parameters.
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
EVP_PKEY_derive_init() and EVP_PKEY_derive() 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
|
|
|
|
Derive shared secret (for example DH or EC keys):
|
|
|
|
#include <openssl/evp.h>
|
|
#include <openssl/rsa.h>
|
|
|
|
EVP_PKEY_CTX *ctx;
|
|
unsigned char *skey;
|
|
size_t skeylen;
|
|
EVP_PKEY *pkey, *peerkey;
|
|
/* NB: assumes pkey, peerkey have been already set up */
|
|
|
|
ctx = EVP_PKEY_CTX_new(pkey);
|
|
if (!ctx)
|
|
/* Error occurred */
|
|
if (EVP_PKEY_derive_init(ctx) <= 0)
|
|
/* Error */
|
|
if (EVP_PKEY_derive_set_peer(ctx, peerkey) <= 0)
|
|
/* Error */
|
|
|
|
/* Determine buffer length */
|
|
if (EVP_PKEY_derive(ctx, NULL, &skeylen) <= 0)
|
|
/* Error */
|
|
|
|
skey = OPENSSL_malloc(skeylen);
|
|
|
|
if (!skey)
|
|
/* malloc failure */
|
|
|
|
if (EVP_PKEY_derive(ctx, skey, &skeylen) <= 0)
|
|
/* Error */
|
|
|
|
/* Shared secret is skey bytes written to buffer skey */
|
|
|
|
=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_verify_recover(3)>,
|
|
|
|
=head1 HISTORY
|
|
|
|
These functions were first added to OpenSSL 1.0.0.
|
|
|
|
=head1 COPYRIGHT
|
|
|
|
Copyright 2006-2016 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
|