1PROVIDER-KEM(7ossl) OpenSSL PROVIDER-KEM(7ossl)
2
6 provider-kem - The kem library <-> provider functions
7
9 #include <openssl/core_dispatch.h>
10 #include <openssl/core_names.h>
11 /*
13 * None of these are actual functions, but are displayed like this for
14 * the function signatures for functions that are offered as function
15 * pointers in OSSL_DISPATCH arrays.
16 */
17 /* Context management */
19 void *OSSL_FUNC_kem_newctx(void *provctx);
20 void OSSL_FUNC_kem_freectx(void *ctx);
21 void *OSSL_FUNC_kem_dupctx(void *ctx);
22 /* Encapsulation */
24 int OSSL_FUNC_kem_encapsulate_init(void *ctx, void *provkey, const char *name,
25 const OSSL_PARAM params[]);
26 int OSSL_FUNC_kem_encapsulate(void *ctx, unsigned char *out, size_t *outlen,
27 unsigned char *secret, size_t *secretlen);
28 /* Decapsulation */
30 int OSSL_FUNC_kem_decapsulate_init(void *ctx, void *provkey, const char *name);
31 int OSSL_FUNC_kem_decapsulate(void *ctx, unsigned char *out, size_t *outlen,
32 const unsigned char *in, size_t inlen);
33 /* KEM parameters */
35 int OSSL_FUNC_kem_get_ctx_params(void *ctx, OSSL_PARAM params[]);
36 const OSSL_PARAM *OSSL_FUNC_kem_gettable_ctx_params(void *ctx, void *provctx);
37 int OSSL_FUNC_kem_set_ctx_params(void *ctx, const OSSL_PARAM params[]);
38 const OSSL_PARAM *OSSL_FUNC_kem_settable_ctx_params(void *ctx, void *provctx);
39
41 This documentation is primarily aimed at provider authors. See
42 provider(7) for further information.
43 The asymmetric kem (OSSL_OP_KEM) operation enables providers to
45 implement asymmetric kem algorithms and make them available to
46 applications via the API functions EVP_PKEY_encapsulate(3),
47 EVP_PKEY_decapsulate(3) and other related functions.
48 All "functions" mentioned here are passed as function pointers between
50 libcrypto and the provider in OSSL_DISPATCH(3) arrays via
51 OSSL_ALGORITHM(3) arrays that are returned by the provider's
52 provider_query_operation() function (see "Provider Functions" in
53 provider-base(7)).
54 All these "functions" have a corresponding function type definition
56 named OSSL_FUNC_{name}_fn, and a helper function to retrieve the
57 function pointer from an OSSL_DISPATCH(3) element named
58 OSSL_FUNC_{name}. For example, the "function" OSSL_FUNC_kem_newctx()
59 has these:
60 typedef void *(OSSL_FUNC_kem_newctx_fn)(void *provctx);
62 static ossl_inline OSSL_FUNC_kem_newctx_fn
63 OSSL_FUNC_kem_newctx(const OSSL_DISPATCH *opf);
64 OSSL_DISPATCH(3) arrays are indexed by numbers that are provided as
66 macros in openssl-core_dispatch.h(7), as follows:
67 OSSL_FUNC_kem_newctx OSSL_FUNC_KEM_NEWCTX
69 OSSL_FUNC_kem_freectx OSSL_FUNC_KEM_FREECTX
70 OSSL_FUNC_kem_dupctx OSSL_FUNC_KEM_DUPCTX
71 OSSL_FUNC_kem_encapsulate_init OSSL_FUNC_KEM_ENCAPSULATE_INIT
73 OSSL_FUNC_kem_encapsulate OSSL_FUNC_KEM_ENCAPSULATE
74 OSSL_FUNC_kem_decapsulate_init OSSL_FUNC_KEM_DECAPSULATE_INIT
76 OSSL_FUNC_kem_decapsulate OSSL_FUNC_KEM_DECAPSULATE
77 OSSL_FUNC_kem_get_ctx_params OSSL_FUNC_KEM_GET_CTX_PARAMS
79 OSSL_FUNC_kem_gettable_ctx_params OSSL_FUNC_KEM_GETTABLE_CTX_PARAMS
80 OSSL_FUNC_kem_set_ctx_params OSSL_FUNC_KEM_SET_CTX_PARAMS
81 OSSL_FUNC_kem_settable_ctx_params OSSL_FUNC_KEM_SETTABLE_CTX_PARAMS
82 An asymmetric kem algorithm implementation may not implement all of
84 these functions. In order to be a consistent set of functions a
85 provider must implement OSSL_FUNC_kem_newctx and OSSL_FUNC_kem_freectx.
86 It must also implement both of OSSL_FUNC_kem_encapsulate_init and
87 OSSL_FUNC_kem_encapsulate, or both of OSSL_FUNC_kem_decapsulate_init
88 and OSSL_FUNC_kem_decapsulate. OSSL_FUNC_kem_get_ctx_params is
89 optional but if it is present then so must
90 OSSL_FUNC_kem_gettable_ctx_params. Similarly,
91 OSSL_FUNC_kem_set_ctx_params is optional but if it is present then so
92 must OSSL_FUNC_kem_settable_ctx_params.
93 An asymmetric kem algorithm must also implement some mechanism for
95 generating, loading or importing keys via the key management
96 (OSSL_OP_KEYMGMT) operation. See provider-keymgmt(7) for further
97 details.
98 Context Management Functions
100 OSSL_FUNC_kem_newctx() should create and return a pointer to a provider
101 side structure for holding context information during an asymmetric kem
102 operation. A pointer to this context will be passed back in a number
103 of the other asymmetric kem operation function calls. The parameter
104 provctx is the provider context generated during provider
105 initialisation (see provider(7)).
106 OSSL_FUNC_kem_freectx() is passed a pointer to the provider side
108 asymmetric kem context in the ctx parameter. This function should free
109 any resources associated with that context.
110 OSSL_FUNC_kem_dupctx() should duplicate the provider side asymmetric
112 kem context in the ctx parameter and return the duplicate copy.
113 Asymmetric Key Encapsulation Functions
115 OSSL_FUNC_kem_encapsulate_init() initialises a context for an
116 asymmetric encapsulation given a provider side asymmetric kem context
117 in the ctx parameter, a pointer to a provider key object in the provkey
118 parameter and the name of the algorithm. The params, if not NULL,
119 should be set on the context in a manner similar to using
120 OSSL_FUNC_kem_set_ctx_params(). The key object should have been
121 previously generated, loaded or imported into the provider using the
122 key management (OSSL_OP_KEYMGMT) operation (see provider-keymgmt(7)>.
123 OSSL_FUNC_kem_encapsulate() performs the actual encapsulation itself.
125 A previously initialised asymmetric kem context is passed in the ctx
126 parameter. Unless out is NULL, the data to be encapsulated is
127 internally generated, and returned into the buffer pointed to by the
128 secret parameter and the encapsulated data should also be written to
129 the location pointed to by the out parameter. The length of the
130 encapsulated data should be written to *outlen and the length of the
131 generated secret should be written to *secretlen.
132 If out is NULL then the maximum length of the encapsulated data should
134 be written to *outlen, and the maximum length of the generated secret
135 should be written to *secretlen.
136 Decapsulation Functions
138 OSSL_FUNC_kem_decapsulate_init() initialises a context for an
139 asymmetric decapsulation given a provider side asymmetric kem context
140 in the ctx parameter, a pointer to a provider key object in the provkey
141 parameter, and a name of the algorithm. The key object should have
142 been previously generated, loaded or imported into the provider using
143 the key management (OSSL_OP_KEYMGMT) operation (see
144 provider-keymgmt(7)>.
145 OSSL_FUNC_kem_decapsulate() performs the actual decapsulation itself.
147 A previously initialised asymmetric kem context is passed in the ctx
148 parameter. The data to be decapsulated is pointed to by the in
149 parameter which is inlen bytes long. Unless out is NULL, the
150 decapsulated data should be written to the location pointed to by the
151 out parameter. The length of the decapsulated data should be written
152 to *outlen. If out is NULL then the maximum length of the decapsulated
153 data should be written to *outlen.
154 Asymmetric Key Encapsulation Parameters
156 See OSSL_PARAM(3) for further details on the parameters structure used
157 by the OSSL_FUNC_kem_get_ctx_params() and
158 OSSL_FUNC_kem_set_ctx_params() functions.
159 OSSL_FUNC_kem_get_ctx_params() gets asymmetric kem parameters
161 associated with the given provider side asymmetric kem context ctx and
162 stores them in params. Passing NULL for params should return true.
163 OSSL_FUNC_kem_set_ctx_params() sets the asymmetric kem parameters
165 associated with the given provider side asymmetric kem context ctx to
166 params. Any parameter settings are additional to any that were
167 previously set. Passing NULL for params should return true.
168 No parameters are currently recognised by built-in asymmetric kem
170 algorithms.
171 OSSL_FUNC_kem_gettable_ctx_params() and
173 OSSL_FUNC_kem_settable_ctx_params() get a constant OSSL_PARAM(3) array
174 that describes the gettable and settable parameters, i.e. parameters
175 that can be used with OSSL_FUNC_kem_get_ctx_params() and
176 OSSL_FUNC_kem_set_ctx_params() respectively.
177
179 OSSL_FUNC_kem_newctx() and OSSL_FUNC_kem_dupctx() should return the
180 newly created provider side asymmetric kem context, or NULL on failure.
181 All other functions should return 1 for success or 0 on error.
183
185 provider(7)
186
188 The provider KEM interface was introduced in OpenSSL 3.0.
189
191 Copyright 2020-2022 The OpenSSL Project Authors. All Rights Reserved.
192 Licensed under the Apache License 2.0 (the "License"). You may not use
194 this file except in compliance with the License. You can obtain a copy
195 in the file LICENSE in the source distribution or at
196 <https://www.openssl.org/source/license.html>.
1973.1.1 2023-08-31 PROVIDER-KEM(7ossl)