1=pod 2 3=head1 NAME 4 5EVP_PKEY_encapsulate_init, EVP_PKEY_encapsulate 6- Key encapsulation using a public key algorithm 7 8=head1 SYNOPSIS 9 10 #include <openssl/evp.h> 11 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); 16 17=head1 DESCRIPTION 18 19The EVP_PKEY_encapsulate_init() function initializes a public key algorithm 20context I<ctx> for an encapsulation operation and then sets the I<params> 21on the context in the same way as calling L<EVP_PKEY_CTX_set_params(3)>. 22 23The EVP_PKEY_encapsulate() function performs a public key encapsulation 24operation using I<ctx> with the name I<name>. 25If I<out> is B<NULL> then the maximum size of the output buffer is written to the 26I<*outlen> parameter and the maximum size of the generated key buffer is written 27to I<*genkeylen>. If I<out> is not B<NULL> and the call is successful then the 28internally generated key is written to I<genkey> and its size is written to 29I<*genkeylen>. The encapsulated version of the generated key is written to 30I<out> and its size is written to I<*outlen>. 31 32=head1 NOTES 33 34After the call to EVP_PKEY_encapsulate_init() algorithm specific parameters 35for the operation may be set or modified using L<EVP_PKEY_CTX_set_params(3)>. 36 37=head1 RETURN VALUES 38 39EVP_PKEY_encapsulate_init() and EVP_PKEY_encapsulate() return 1 for 40success and 0 or a negative value for failure. In particular a return value of -2 41indicates the operation is not supported by the public key algorithm. 42 43=head1 EXAMPLES 44 45Encapsulate an RSASVE key (for RSA keys). 46 47 #include <openssl/evp.h> 48 49 /* 50 * NB: assumes rsa_pub_key is an public key of another party. 51 */ 52 53 EVP_PKEY_CTX *ctx = NULL; 54 size_t secretlen = 0, outlen = 0; 55 unsigned char *out = NULL, *secret = NULL; 56 57 ctx = EVP_PKEY_CTX_new_from_pkey(libctx, rsa_pub_key, NULL); 58 if (ctx = NULL) 59 /* Error */ 60 if (EVP_PKEY_encapsulate_init(ctx, NULL) <= 0) 61 /* Error */ 62 63 /* Set the mode - only 'RSASVE' is currently supported */ 64 if (EVP_PKEY_CTX_set_kem_op(ctx, "RSASVE") <= 0) 65 /* Error */ 66 /* Determine buffer length */ 67 if (EVP_PKEY_encapsulate(ctx, NULL, &outlen, NULL, &secretlen) <= 0) 68 /* Error */ 69 70 out = OPENSSL_malloc(outlen); 71 secret = OPENSSL_malloc(secretlen); 72 if (out == NULL || secret == NULL) 73 /* malloc failure */ 74 75 /* 76 * The generated 'secret' can be used as key material. 77 * The encapsulated 'out' can be sent to another party who can 78 * decapsulate it using their private key to retrieve the 'secret'. 79 */ 80 if (EVP_PKEY_encapsulate(ctx, out, &outlen, secret, &secretlen) <= 0) 81 /* Error */ 82 83=head1 SEE ALSO 84 85L<EVP_PKEY_CTX_new(3)>, 86L<EVP_PKEY_decapsulate(3)>, 87L<EVP_KEM-RSA(7)>, 88 89=head1 HISTORY 90 91These functions were added in OpenSSL 3.0. 92 93=head1 COPYRIGHT 94 95Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved. 96 97Licensed under the Apache License 2.0 (the "License"). You may not use 98this file except in compliance with the License. You can obtain a copy 99in the file LICENSE in the source distribution or at 100L<https://www.openssl.org/source/license.html>. 101 102=cut 103
