1EVP_PKEY_ENCAPSULATE(3ossl)         OpenSSL        EVP_PKEY_ENCAPSULATE(3ossl)
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NAME

6       EVP_PKEY_encapsulate_init, EVP_PKEY_encapsulate - Key encapsulation
7       using a public key algorithm
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SYNOPSIS

10        #include <openssl/evp.h>
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12        int EVP_PKEY_encapsulate_init(EVP_PKEY_CTX *ctx, const OSSL_PARAM params[]);
13        int EVP_PKEY_encapsulate(EVP_PKEY_CTX *ctx,
14                                 unsigned char *out, size_t *outlen,
15                                 unsigned char *genkey, size_t *genkeylen);
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DESCRIPTION

18       The EVP_PKEY_encapsulate_init() function initializes a public key
19       algorithm context ctx for an encapsulation operation and then sets the
20       params on the context in the same way as calling
21       EVP_PKEY_CTX_set_params(3).
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23       The EVP_PKEY_encapsulate() function performs a public key encapsulation
24       operation using ctx with the name name.  If out is NULL then the
25       maximum size of the output buffer is written to the *outlen parameter
26       and the maximum size of the generated key buffer is written to
27       *genkeylen. If out is not NULL and the call is successful then the
28       internally generated key is written to genkey and its size is written
29       to *genkeylen. The encapsulated version of the generated key is written
30       to out and its size is written to *outlen.
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NOTES

33       After the call to EVP_PKEY_encapsulate_init() algorithm specific
34       parameters for the operation may be set or modified using
35       EVP_PKEY_CTX_set_params(3).
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RETURN VALUES

38       EVP_PKEY_encapsulate_init() and EVP_PKEY_encapsulate() return 1 for
39       success and 0 or a negative value for failure. In particular a return
40       value of -2 indicates the operation is not supported by the public key
41       algorithm.
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EXAMPLES

44       Encapsulate an RSASVE key (for RSA keys).
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46        #include <openssl/evp.h>
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48        /*
49         * NB: assumes rsa_pub_key is an public key of another party.
50         */
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52        EVP_PKEY_CTX *ctx = NULL;
53        size_t secretlen = 0, outlen = 0;
54        unsigned char *out = NULL, *secret = NULL;
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56        ctx = EVP_PKEY_CTX_new_from_pkey(libctx, rsa_pub_key, NULL);
57        if (ctx = NULL)
58            /* Error */
59        if (EVP_PKEY_encapsulate_init(ctx, NULL) <= 0)
60            /* Error */
61
62        /* Set the mode - only 'RSASVE' is currently supported */
63         if (EVP_PKEY_CTX_set_kem_op(ctx, "RSASVE") <= 0)
64            /* Error */
65        /* Determine buffer length */
66        if (EVP_PKEY_encapsulate(ctx, NULL, &outlen, NULL, &secretlen) <= 0)
67            /* Error */
68
69        out = OPENSSL_malloc(outlen);
70        secret = OPENSSL_malloc(secretlen);
71        if (out == NULL || secret == NULL)
72            /* malloc failure */
73
74        /*
75         * The generated 'secret' can be used as key material.
76         * The encapsulated 'out' can be sent to another party who can
77         * decapsulate it using their private key to retrieve the 'secret'.
78         */
79        if (EVP_PKEY_encapsulate(ctx, out, &outlen, secret, &secretlen) <= 0)
80            /* Error */
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SEE ALSO

83       EVP_PKEY_CTX_new(3), EVP_PKEY_decapsulate(3), EVP_KEM-RSA(7),
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HISTORY

86       These functions were added in OpenSSL 3.0.
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89       Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.
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91       Licensed under the Apache License 2.0 (the "License").  You may not use
92       this file except in compliance with the License.  You can obtain a copy
93       in the file LICENSE in the source distribution or at
94       <https://www.openssl.org/source/license.html>.
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983.1.1                             2023-08-31       EVP_PKEY_ENCAPSULATE(3ossl)
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