EVP_PKEY_derive - derive public key algorithm shared secret.
#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);
EVP_PKEY_derive(3openssl) OpenSSL EVP_PKEY_derive(3openssl)
NAME
EVP_PKEY_derive_init, EVP_PKEY_derive_set_peer, EVP_PKEY_derive -
derive public key algorithm shared secret.
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);
DESCRIPTION
The EVP_PKEY_derive_init() function initializes a public key algorithm
context using key 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 ctx. If key is
NULL then the maximum size of the output buffer is written to the
keylen parameter. If key is not NULL then before the call the keylen
parameter should contain the length of the key buffer, if the call is
successful the shared secret is written to key and the amount of data
written to keylen.
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
+---------------+--------------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+--------------------------+
|Availability | library/security/openssl |
+---------------+--------------------------+
|Stability | Pass-through uncommitted |
+---------------+--------------------------+
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.
Source code for open source software components in Oracle Solaris can
be found at https://www.oracle.com/downloads/opensource/solaris-source-
code-downloads.html.
This software was built from source available at
https://github.com/oracle/solaris-userland. The original community
source was downloaded from
https://www.openssl.org/source/openssl-1.0.2ze.tar.gz.
Further information about this software can be found on the open source
community website at https://www.openssl.org/.
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.
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 */
SEE ALSO
EVP_PKEY_CTX_new(3), EVP_PKEY_encrypt(3), EVP_PKEY_decrypt(3),
EVP_PKEY_sign(3), EVP_PKEY_verify(3), EVP_PKEY_verify_recover(3),
HISTORY
These functions were first added to OpenSSL 1.0.0.
1.0.2ze 2022-05-03 EVP_PKEY_derive(3openssl)