5 EVP_PKEY_decapsulate_init, EVP_PKEY_decapsulate
6 - Key decapsulation using a private key algorithm
10 #include <openssl/evp.h>
12 int EVP_PKEY_decapsulate_init(EVP_PKEY_CTX *ctx, const OSSL_PARAM params[]);
13 int EVP_PKEY_decapsulate(EVP_PKEY_CTX *ctx,
14 unsigned char *secret, size_t *secretlen,
15 const unsigned char *wrapped, size_t wrappedlen);
19 The EVP_PKEY_decapsulate_init() function initializes a private key algorithm
20 context I<ctx> for a decapsulation operation and then sets the I<params>
21 on the context in the same way as calling L<EVP_PKEY_CTX_set_params(3)>.
23 The EVP_PKEY_decapsulate() function performs a private key decapsulation
24 operation using I<ctx>. The data to be decapsulated is specified using the
25 I<wrapped> and I<wrappedlen> parameters.
26 If I<secret> is I<NULL> then the maximum size of the output secret buffer
27 is written to the I<*secretlen> parameter. If I<secret> is not B<NULL> and the
28 call is successful then the decapsulated secret data is written to I<secret> and
29 the amount of data written to I<secretlen>.
33 After the call to EVP_PKEY_decapsulate_init() algorithm specific parameters
34 for the operation may be set or modified using L<EVP_PKEY_CTX_set_params(3)>.
38 EVP_PKEY_decapsulate_init() and EVP_PKEY_decapsulate() return 1 for
39 success and 0 or a negative value for failure. In particular a return value of -2
40 indicates the operation is not supported by the private key algorithm.
44 Decapsulate data using RSA:
46 #include <openssl/evp.h>
49 * NB: assumes rsa_priv_key is an RSA private key,
50 * and that in, inlen are already set up to contain encapsulated data.
53 EVP_PKEY_CTX *ctx = NULL;
55 unsigned char *secret = NULL;;
57 ctx = EVP_PKEY_CTX_new_from_pkey(libctx, rsa_priv_key, NULL);
60 if (EVP_PKEY_decapsulate_init(ctx, NULL) <= 0)
63 /* Set the mode - only 'RSASVE' is currently supported */
64 if (EVP_PKEY_CTX_set_kem_op(ctx, "RSASVE") <= 0)
67 /* Determine buffer length */
68 if (EVP_PKEY_decapsulate(ctx, NULL, &secretlen, in, inlen) <= 0)
71 secret = OPENSSL_malloc(secretlen);
75 /* Decapsulated secret data is secretlen bytes long */
76 if (EVP_PKEY_decapsulaterctx, secret, &secretlen, in, inlen) <= 0)
82 L<EVP_PKEY_CTX_new(3)>,
83 L<EVP_PKEY_encapsulate(3)>,
88 These functions were added in OpenSSL 3.0.
92 Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.
94 Licensed under the Apache License 2.0 (the "License"). You may not use
95 this file except in compliance with the License. You can obtain a copy
96 in the file LICENSE in the source distribution or at
97 L<https://www.openssl.org/source/license.html>.