EVP_PKEY_ENCAPSULATE(3SSL) OpenSSL EVP_PKEY_ENCAPSULATE(3SSL)
NAME
EVP_PKEY_encapsulate_init, EVP_PKEY_encapsulate - Key encapsulation
using a public key algorithm
SYNOPSIS
#include <openssl/evp.h>
int EVP_PKEY_encapsulate_init(EVP_PKEY_CTX *ctx, const OSSL_PARAM params[]);
int EVP_PKEY_encapsulate(EVP_PKEY_CTX *ctx,
unsigned char *out, size_t *outlen,
unsigned char *genkey, size_t *genkeylen);
DESCRIPTION
The EVP_PKEY_encapsulate_init() function initializes a public key
algorithm context ctx for an encapsulation operation and then sets the
params on the context in the same way as calling
EVP_PKEY_CTX_set_params(3).
The EVP_PKEY_encapsulate() function performs a public key encapsulation
operation using ctx with the name name. If out is NULL then the
maximum size of the output buffer is written to the *outlen parameter
and the maximum size of the generated key buffer is written to
*genkeylen. If out is not NULL and the call is successful then the
internally generated key is written to genkey and its size is written
to *genkeylen. The encapsulated version of the generated key is written
to out and its size is written to *outlen.
NOTES
After the call to EVP_PKEY_encapsulate_init() algorithm specific
parameters for the operation may be set or modified using
EVP_PKEY_CTX_set_params(3).
RETURN VALUES
EVP_PKEY_encapsulate_init() and EVP_PKEY_encapsulate() 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.
EXAMPLES
Encapsulate an RSASVE key (for RSA keys).
#include <openssl/evp.h>
/*
* NB: assumes rsa_pub_key is an public key of another party.
*/
EVP_PKEY_CTX *ctx = NULL;
size_t secretlen = 0, outlen = 0;
unsigned char *out = NULL, *secret = NULL;
ctx = EVP_PKEY_CTX_new_from_pkey(libctx, rsa_pub_key, NULL);
if (ctx = NULL)
/* Error */
if (EVP_PKEY_encapsulate_init(ctx, NULL) <= 0)
/* Error */
/* Set the mode - only 'RSASVE' is currently supported */
if (EVP_PKEY_CTX_set_kem_op(ctx, "RSASVE") <= 0)
/* Error */
/* Determine buffer length */
if (EVP_PKEY_encapsulate(ctx, NULL, &outlen, NULL, &secretlen) <= 0)
/* Error */
out = OPENSSL_malloc(outlen);
secret = OPENSSL_malloc(secretlen);
if (out == NULL || secret == NULL)
/* malloc failure */
/*
* The generated 'secret' can be used as key material.
* The encapsulated 'out' can be sent to another party who can
* decapsulate it using their private key to retrieve the 'secret'.
*/
if (EVP_PKEY_encapsulate(ctx, out, &outlen, secret, &secretlen) <= 0)
/* Error */
SEE ALSO
EVP_PKEY_CTX_new(3), EVP_PKEY_decapsulate(3), EVP_KEM-RSA(7),
HISTORY
These functions were added in OpenSSL 3.0.
COPYRIGHT
Copyright 2020-2021 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
<https://www.openssl.org/source/license.html>.
3.0.2 2024-08-20 EVP_PKEY_ENCAPSULATE(3SSL)
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