| 1 | =pod
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| 2 |
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| 3 | =head1 NAME
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| 4 |
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| 5 | EVP_KEM_fetch, EVP_KEM_free, EVP_KEM_up_ref,
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| 6 | EVP_KEM_get0_name, EVP_KEM_is_a, EVP_KEM_get0_provider,
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| 7 | EVP_KEM_do_all_provided, EVP_KEM_names_do_all, EVP_KEM_get0_description,
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| 8 | EVP_KEM_gettable_ctx_params, EVP_KEM_settable_ctx_params
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| 9 | - Functions to manage EVP_KEM algorithm objects
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| 10 |
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| 11 | =head1 SYNOPSIS
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| 12 |
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| 13 | #include <openssl/evp.h>
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| 14 |
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| 15 | EVP_KEM *EVP_KEM_fetch(OSSL_LIB_CTX *ctx, const char *algorithm,
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| 16 | const char *properties);
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| 17 | void EVP_KEM_free(EVP_KEM *kem);
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| 18 | int EVP_KEM_up_ref(EVP_KEM *kem);
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| 19 | const char *EVP_KEM_get0_name(const EVP_KEM *kem);
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| 20 | int EVP_KEM_is_a(const EVP_KEM *kem, const char *name);
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| 21 | OSSL_PROVIDER *EVP_KEM_get0_provider(const EVP_KEM *kem);
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| 22 | void EVP_KEM_do_all_provided(OSSL_LIB_CTX *libctx,
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| 23 | void (*fn)(EVP_KEM *kem, void *arg), void *arg);
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| 24 | int EVP_KEM_names_do_all(const EVP_KEM *kem,
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| 25 | void (*fn)(const char *name, void *data), void *data);
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| 26 | const char *EVP_KEM_get0_description(const EVP_KEM *kem);
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| 27 | const OSSL_PARAM *EVP_KEM_gettable_ctx_params(const EVP_KEM *kem);
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| 28 | const OSSL_PARAM *EVP_KEM_settable_ctx_params(const EVP_KEM *kem);
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| 29 |
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| 30 | =head1 DESCRIPTION
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| 31 |
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| 32 | EVP_KEM_fetch() fetches the implementation for the given B<algorithm> from any
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| 33 | provider offering it, within the criteria given by the B<properties> and in the
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| 34 | scope of the given library context B<ctx> (see L<OSSL_LIB_CTX(3)>). The algorithm
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| 35 | will be one offering functions for performing asymmetric kem related tasks such
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| 36 | as key encapsulation and decapsulation.
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| 37 | See L<crypto(7)/ALGORITHM FETCHING> for further information.
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| 38 |
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| 39 | The returned value must eventually be freed with EVP_KEM_free().
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| 40 |
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| 41 | EVP_KEM_free() decrements the reference count for the B<EVP_KEM> structure.
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| 42 | Typically this structure will have been obtained from an earlier call to
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| 43 | EVP_KEM_fetch(). If the reference count drops to 0 then the structure is freed.
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| 44 |
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| 45 | EVP_KEM_up_ref() increments the reference count for an B<EVP_KEM> structure.
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| 46 |
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| 47 | EVP_KEM_is_a() returns 1 if I<kem> is an implementation of an
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| 48 | algorithm that's identifiable with I<name>, otherwise 0.
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| 49 |
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| 50 | EVP_KEM_get0_provider() returns the provider that I<kem> was fetched from.
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| 51 |
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| 52 | EVP_KEM_do_all_provided() traverses all EVP_KEMs implemented by all activated
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| 53 | providers in the given library context I<libctx>, and for each of the
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| 54 | implementations, calls the given function I<fn> with the implementation method
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| 55 | and the given I<arg> as argument.
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| 56 |
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| 57 | EVP_KEM_get0_name() returns the algorithm name from the provided
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| 58 | implementation for the given I<kem>. Note that the I<kem> may have
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| 59 | multiple synonyms associated with it. In this case the first name from the
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| 60 | algorithm definition is returned. Ownership of the returned string is retained
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| 61 | by the I<kem> object and should not be freed by the caller.
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| 62 |
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| 63 | EVP_KEM_names_do_all() traverses all names for I<kem>, and calls I<fn> with
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| 64 | each name and I<data>.
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| 65 |
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| 66 | EVP_KEM_get0_description() returns a description of the I<kem>, meant for
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| 67 | display and human consumption. The description is at the discretion of
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| 68 | the I<kem> implementation.
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| 69 |
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| 70 | EVP_KEM_gettable_ctx_params() and EVP_KEM_settable_ctx_params() return
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| 71 | a constant B<OSSL_PARAM> array that describes the names and types of key
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| 72 | parameters that can be retrieved or set by a key encapsulation algorithm using
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| 73 | L<EVP_PKEY_CTX_get_params(3)> and L<EVP_PKEY_CTX_set_params(3)>.
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| 74 |
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| 75 | =head1 RETURN VALUES
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| 76 |
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| 77 | EVP_KEM_fetch() returns a pointer to an B<EVP_KEM> for success or B<NULL> for
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| 78 | failure.
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| 79 |
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| 80 | EVP_KEM_up_ref() returns 1 for success or 0 otherwise.
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| 81 |
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| 82 | EVP_KEM_names_do_all() returns 1 if the callback was called for all names. A
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| 83 | return value of 0 means that the callback was not called for any names.
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| 84 |
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| 85 | EVP_KEM_gettable_ctx_params() and EVP_KEM_settable_ctx_params() return
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| 86 | a constant B<OSSL_PARAM> array or NULL on error.
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| 87 |
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| 88 | =head1 SEE ALSO
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| 89 |
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| 90 | L<crypto(7)/ALGORITHM FETCHING>, L<OSSL_PROVIDER(3)>
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| 91 |
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| 92 | =head1 HISTORY
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| 93 |
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| 94 | The functions described here were added in OpenSSL 3.0.
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| 95 |
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| 96 | =head1 COPYRIGHT
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| 97 |
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| 98 | Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.
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| 99 |
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| 100 | Licensed under the Apache License 2.0 (the "License"). You may not use
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| 101 | this file except in compliance with the License. You can obtain a copy
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| 102 | in the file LICENSE in the source distribution or at
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| 103 | L<https://www.openssl.org/source/license.html>.
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| 104 |
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| 105 | =cut
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