1=pod 2 3=head1 NAME 4 5EVP_PKEY_decapsulate_init, EVP_PKEY_decapsulate 6- Key decapsulation using a private key algorithm 7 8=head1 SYNOPSIS 9 10 #include <openssl/evp.h> 11 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); 16 17=head1 DESCRIPTION 18 19The EVP_PKEY_decapsulate_init() function initializes a private key algorithm 20context I<ctx> for a decapsulation 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_decapsulate() function performs a private key decapsulation 24operation using I<ctx>. The data to be decapsulated is specified using the 25I<wrapped> and I<wrappedlen> parameters. 26If I<secret> is I<NULL> then the maximum size of the output secret buffer 27is written to the I<*secretlen> parameter. If I<secret> is not B<NULL> and the 28call is successful then the decapsulated secret data is written to I<secret> and 29the amount of data written to I<secretlen>. 30 31=head1 NOTES 32 33After the call to EVP_PKEY_decapsulate_init() algorithm specific parameters 34for the operation may be set or modified using L<EVP_PKEY_CTX_set_params(3)>. 35 36=head1 RETURN VALUES 37 38EVP_PKEY_decapsulate_init() and EVP_PKEY_decapsulate() return 1 for 39success and 0 or a negative value for failure. In particular a return value of -2 40indicates the operation is not supported by the private key algorithm. 41 42=head1 EXAMPLES 43 44Decapsulate data using RSA: 45 46 #include <openssl/evp.h> 47 48 /* 49 * NB: assumes rsa_priv_key is an RSA private key, 50 * and that in, inlen are already set up to contain encapsulated data. 51 */ 52 53 EVP_PKEY_CTX *ctx = NULL; 54 size_t secretlen = 0; 55 unsigned char *secret = NULL;; 56 57 ctx = EVP_PKEY_CTX_new_from_pkey(libctx, rsa_priv_key, NULL); 58 if (ctx = NULL) 59 /* Error */ 60 if (EVP_PKEY_decapsulate_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 67 /* Determine buffer length */ 68 if (EVP_PKEY_decapsulate(ctx, NULL, &secretlen, in, inlen) <= 0) 69 /* Error */ 70 71 secret = OPENSSL_malloc(secretlen); 72 if (secret == NULL) 73 /* malloc failure */ 74 75 /* Decapsulated secret data is secretlen bytes long */ 76 if (EVP_PKEY_decapsulaterctx, secret, &secretlen, in, inlen) <= 0) 77 /* Error */ 78 79 80=head1 SEE ALSO 81 82L<EVP_PKEY_CTX_new(3)>, 83L<EVP_PKEY_encapsulate(3)>, 84L<EVP_KEM-RSA(7)>, 85 86=head1 HISTORY 87 88These functions were added in OpenSSL 3.0. 89 90=head1 COPYRIGHT 91 92Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved. 93 94Licensed under the Apache License 2.0 (the "License"). You may not use 95this file except in compliance with the License. You can obtain a copy 96in the file LICENSE in the source distribution or at 97L<https://www.openssl.org/source/license.html>. 98 99=cut 100