=pod =head1 NAME EVP_PKEY_encapsulate_init, EVP_PKEY_encapsulate - Key encapsulation using a public key algorithm =head1 SYNOPSIS #include int EVP_PKEY_encapsulate_init(EVP_PKEY_CTX *ctx); int EVP_PKEY_encapsulate(EVP_PKEY_CTX *ctx, unsigned char *out, size_t *outlen, unsigned char *genkey, size_t *genkeylen); =head1 DESCRIPTION The EVP_PKEY_encapsulate_init() function initializes a public key algorithm context I for an encapsulation operation. The EVP_PKEY_encapsulate() function performs a public key encapsulation operation using I with the name I. If I is B then the maximum size of the output buffer is written to the I<*outlen> parameter and the maximum size of the generated key buffer is written to I<*genkeylen>. If I is not B and the call is successful then the internally generated key is written to I and its size is written to I<*genkeylen>. The encapsulated version of the generated key is written to I and its size is written to I<*outlen>. =head1 NOTES After the call to EVP_PKEY_encapsulate_init() algorithm specific parameters for the operation may be set using L. =head1 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. =head1 EXAMPLES Encapsulate an RSASVE key (for RSA keys). #include /* * 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) <= 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 */ =head1 SEE ALSO L, L, L, =head1 HISTORY These functions were added in OpenSSL 3.0. =head1 COPYRIGHT Copyright 2020 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 L. =cut