| 1 | =pod
|
|---|
| 2 |
|
|---|
| 3 | =head1 NAME
|
|---|
| 4 |
|
|---|
| 5 | EVP_PKEY_encapsulate_init, EVP_PKEY_encapsulate
|
|---|
| 6 | - Key encapsulation using a KEM algorithm with a public key
|
|---|
| 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 *wrappedkey, size_t *wrappedkeylen,
|
|---|
| 15 | unsigned char *genkey, size_t *genkeylen);
|
|---|
| 16 |
|
|---|
| 17 | =head1 DESCRIPTION
|
|---|
| 18 |
|
|---|
| 19 | The EVP_PKEY_encapsulate_init() function initializes a public key algorithm
|
|---|
| 20 | context I<ctx> for an encapsulation operation and then sets the I<params>
|
|---|
| 21 | on the context in the same way as calling L<EVP_PKEY_CTX_set_params(3)>.
|
|---|
| 22 | Note that I<ctx> is usually is produced using L<EVP_PKEY_CTX_new_from_pkey(3)>,
|
|---|
| 23 | specifying the public key to use.
|
|---|
| 24 |
|
|---|
| 25 | The EVP_PKEY_encapsulate() function performs a public key encapsulation
|
|---|
| 26 | operation using I<ctx>.
|
|---|
| 27 | The symmetric secret generated in I<genkey> can be used as key material.
|
|---|
| 28 | The ciphertext in I<wrappedkey> is its encapsulated form, which can be sent
|
|---|
| 29 | to another party, who can use L<EVP_PKEY_decapsulate(3)> to retrieve it
|
|---|
| 30 | using their private key.
|
|---|
| 31 | If I<wrappedkey> is NULL then the maximum size of the output buffer
|
|---|
| 32 | is written to the I<*wrappedkeylen> parameter unless I<wrappedkeylen> is NULL
|
|---|
| 33 | and the maximum size of the generated key buffer is written to I<*genkeylen>
|
|---|
| 34 | unless I<genkeylen> is NULL.
|
|---|
| 35 | If I<wrappedkey> is not NULL and the call is successful then the
|
|---|
| 36 | internally generated key is written to I<genkey> and its size is written to
|
|---|
| 37 | I<*genkeylen>. The encapsulated version of the generated key is written to
|
|---|
| 38 | I<wrappedkey> and its size is written to I<*wrappedkeylen>.
|
|---|
| 39 |
|
|---|
| 40 | =head1 NOTES
|
|---|
| 41 |
|
|---|
| 42 | After the call to EVP_PKEY_encapsulate_init() algorithm-specific parameters
|
|---|
| 43 | for the operation may be set or modified using L<EVP_PKEY_CTX_set_params(3)>.
|
|---|
| 44 |
|
|---|
| 45 | =head1 RETURN VALUES
|
|---|
| 46 |
|
|---|
| 47 | EVP_PKEY_encapsulate_init() and EVP_PKEY_encapsulate() return 1 for
|
|---|
| 48 | success and 0 or a negative value for failure. In particular a return value of -2
|
|---|
| 49 | indicates the operation is not supported by the public key algorithm.
|
|---|
| 50 |
|
|---|
| 51 | =head1 EXAMPLES
|
|---|
| 52 |
|
|---|
| 53 | Encapsulate an RSASVE key (for RSA keys).
|
|---|
| 54 |
|
|---|
| 55 | #include <openssl/evp.h>
|
|---|
| 56 |
|
|---|
| 57 | /*
|
|---|
| 58 | * NB: assumes rsa_pub_key is an public key of another party.
|
|---|
| 59 | */
|
|---|
| 60 |
|
|---|
| 61 | EVP_PKEY_CTX *ctx = NULL;
|
|---|
| 62 | size_t secretlen = 0, outlen = 0;
|
|---|
| 63 | unsigned char *out = NULL, *secret = NULL;
|
|---|
| 64 |
|
|---|
| 65 | ctx = EVP_PKEY_CTX_new_from_pkey(libctx, rsa_pub_key, NULL);
|
|---|
| 66 | if (ctx = NULL)
|
|---|
| 67 | /* Error */
|
|---|
| 68 | if (EVP_PKEY_encapsulate_init(ctx, NULL) <= 0)
|
|---|
| 69 | /* Error */
|
|---|
| 70 |
|
|---|
| 71 | /* Set the mode - only 'RSASVE' is currently supported */
|
|---|
| 72 | if (EVP_PKEY_CTX_set_kem_op(ctx, "RSASVE") <= 0)
|
|---|
| 73 | /* Error */
|
|---|
| 74 | /* Determine buffer length */
|
|---|
| 75 | if (EVP_PKEY_encapsulate(ctx, NULL, &outlen, NULL, &secretlen) <= 0)
|
|---|
| 76 | /* Error */
|
|---|
| 77 |
|
|---|
| 78 | out = OPENSSL_malloc(outlen);
|
|---|
| 79 | secret = OPENSSL_malloc(secretlen);
|
|---|
| 80 | if (out == NULL || secret == NULL)
|
|---|
| 81 | /* malloc failure */
|
|---|
| 82 |
|
|---|
| 83 | /*
|
|---|
| 84 | * The generated 'secret' can be used as key material.
|
|---|
| 85 | * The encapsulated 'out' can be sent to another party who can
|
|---|
| 86 | * decapsulate it using their private key to retrieve the 'secret'.
|
|---|
| 87 | */
|
|---|
| 88 | if (EVP_PKEY_encapsulate(ctx, out, &outlen, secret, &secretlen) <= 0)
|
|---|
| 89 | /* Error */
|
|---|
| 90 |
|
|---|
| 91 | =head1 SEE ALSO
|
|---|
| 92 |
|
|---|
| 93 | L<EVP_PKEY_CTX_new_from_pkey(3)>,
|
|---|
| 94 | L<EVP_PKEY_decapsulate(3)>,
|
|---|
| 95 | L<EVP_KEM-RSA(7)>,
|
|---|
| 96 |
|
|---|
| 97 | =head1 HISTORY
|
|---|
| 98 |
|
|---|
| 99 | These functions were added in OpenSSL 3.0.
|
|---|
| 100 |
|
|---|
| 101 | =head1 COPYRIGHT
|
|---|
| 102 |
|
|---|
| 103 | Copyright 2020-2023 The OpenSSL Project Authors. All Rights Reserved.
|
|---|
| 104 |
|
|---|
| 105 | Licensed under the Apache License 2.0 (the "License"). You may not use
|
|---|
| 106 | this file except in compliance with the License. You can obtain a copy
|
|---|
| 107 | in the file LICENSE in the source distribution or at
|
|---|
| 108 | L<https://www.openssl.org/source/license.html>.
|
|---|
| 109 |
|
|---|
| 110 | =cut
|
|---|
