1PROVIDER-ENCODER(7ossl) OpenSSL PROVIDER-ENCODER(7ossl)
2
6 provider-encoder - The OSSL_ENCODER library <-> provider functions
7
9 #include <openssl/core_dispatch.h>
10 /*
12 * None of these are actual functions, but are displayed like this for
13 * the function signatures for functions that are offered as function
14 * pointers in OSSL_DISPATCH arrays.
15 */
16 /* Encoder parameter accessor and descriptor */
18 const OSSL_PARAM *OSSL_FUNC_encoder_gettable_params(void *provctx);
19 int OSSL_FUNC_encoder_get_params(OSSL_PARAM params[]);
20 /* Functions to construct / destruct / manipulate the encoder context */
22 void *OSSL_FUNC_encoder_newctx(void *provctx);
23 void OSSL_FUNC_encoder_freectx(void *ctx);
24 int OSSL_FUNC_encoder_set_ctx_params(void *ctx, const OSSL_PARAM params[]);
25 const OSSL_PARAM *OSSL_FUNC_encoder_settable_ctx_params(void *provctx);
26 /* Functions to check selection support */
28 int OSSL_FUNC_encoder_does_selection(void *provctx, int selection);
29 /* Functions to encode object data */
31 int OSSL_FUNC_encoder_encode(void *ctx, OSSL_CORE_BIO *out,
32 const void *obj_raw,
33 const OSSL_PARAM obj_abstract[],
34 int selection,
35 OSSL_PASSPHRASE_CALLBACK *cb,
36 void *cbarg);
37 /* Functions to import and free a temporary object to be encoded */
39 void *OSSL_FUNC_encoder_import_object(void *ctx, int selection,
40 const OSSL_PARAM params[]);
41 void OSSL_FUNC_encoder_free_object(void *obj);
42
44 We use the wide term "encode" in this manual. This includes but is not
45 limited to serialization.
46 The ENCODER operation is a generic method to encode a provider-native
48 object (obj_raw) or an object abstraction (object_abstract, see
49 provider-object(7)) into an encoded form, and write the result to the
50 given OSSL_CORE_BIO. If the caller wants to get the encoded stream to
51 memory, it should provide a BIO_s_mem(3) BIO.
52 The encoder doesn't need to know more about the OSSL_CORE_BIO pointer
54 than being able to pass it to the appropriate BIO upcalls (see "Core
55 functions" in provider-base(7)).
56 The ENCODER implementation may be part of a chain, where data is passed
58 from one to the next. For example, there may be an implementation to
59 encode an object to DER (that object is assumed to be provider-native
60 and thereby passed via obj_raw), and another one that encodes DER to
61 PEM (that one would receive the DER encoding via obj_abstract).
62 The encoding using the OSSL_PARAM(3) array form allows a encoder to be
64 used for data that's been exported from another provider, and thereby
65 allow them to exist independently of each other.
66 The encoding using a provider side object can only be safely used with
68 provider data coming from the same provider, for example keys with the
69 KEYMGMT provider.
70 All "functions" mentioned here are passed as function pointers between
72 libcrypto and the provider in OSSL_DISPATCH(3) arrays via
73 OSSL_ALGORITHM(3) arrays that are returned by the provider's
74 provider_query_operation() function (see "Provider Functions" in
75 provider-base(7)).
76 All these "functions" have a corresponding function type definition
78 named OSSL_FUNC_{name}_fn, and a helper function to retrieve the
79 function pointer from an OSSL_DISPATCH(3) element named
80 OSSL_FUNC_{name}. For example, the "function"
81 OSSL_FUNC_encoder_encode() has these:
82 typedef int
84 (OSSL_FUNC_encoder_encode_fn)(void *ctx, OSSL_CORE_BIO *out,
85 const void *obj_raw,
86 const OSSL_PARAM obj_abstract[],
87 int selection,
88 OSSL_PASSPHRASE_CALLBACK *cb, void *cbarg);
89 static ossl_inline OSSL_FUNC_encoder_encode_fn
90 OSSL_FUNC_encoder_encode(const OSSL_DISPATCH *opf);
91 OSSL_DISPATCH(3) arrays are indexed by numbers that are provided as
93 macros in openssl-core_dispatch.h(7), as follows:
94 OSSL_FUNC_encoder_get_params OSSL_FUNC_ENCODER_GET_PARAMS
96 OSSL_FUNC_encoder_gettable_params OSSL_FUNC_ENCODER_GETTABLE_PARAMS
97 OSSL_FUNC_encoder_newctx OSSL_FUNC_ENCODER_NEWCTX
99 OSSL_FUNC_encoder_freectx OSSL_FUNC_ENCODER_FREECTX
100 OSSL_FUNC_encoder_set_ctx_params OSSL_FUNC_ENCODER_SET_CTX_PARAMS
101 OSSL_FUNC_encoder_settable_ctx_params OSSL_FUNC_ENCODER_SETTABLE_CTX_PARAMS
102 OSSL_FUNC_encoder_does_selection OSSL_FUNC_ENCODER_DOES_SELECTION
104 OSSL_FUNC_encoder_encode OSSL_FUNC_ENCODER_ENCODE
106 OSSL_FUNC_encoder_import_object OSSL_FUNC_ENCODER_IMPORT_OBJECT
108 OSSL_FUNC_encoder_free_object OSSL_FUNC_ENCODER_FREE_OBJECT
109 Names and properties
111 The name of an implementation should match the type of object it
112 handles. For example, an implementation that encodes an RSA key should
113 be named "RSA". Likewise, an implementation that further encodes DER
114 should be named "DER".
115 Properties can be used to further specify details about an
117 implementation:
118 output
120 This property is used to specify what type of output the
121 implementation produces.
122 This property is mandatory.
124 OpenSSL providers recognize the following output types:
126 text
128 An implementation with that output type outputs human readable
129 text, making that implementation suitable for "-text" output in
130 diverse openssl(1) commands.
131 pem An implementation with that output type outputs PEM formatted
133 data.
134 der An implementation with that output type outputs DER formatted
136 data.
137 msblob
139 An implementation with that output type outputs MSBLOB
140 formatted data.
141 pvk An implementation with that output type outputs PVK formatted
143 data.
144 structure
146 This property is used to specify the structure that is used for the
147 encoded object. An example could be "pkcs8", to specify explicitly
148 that an object (presumably an asymmetric key pair, in this case)
149 will be wrapped in a PKCS#8 structure as part of the encoding.
150 This property is optional.
152 The possible values of both these properties is open ended. A provider
154 may very well specify output types and structures that libcrypto
155 doesn't know anything about.
156 Subset selections
158 Sometimes, an object has more than one subset of data that is
159 interesting to treat separately or together. It's possible to specify
160 what subsets are to be encoded, with a set of bits selection that are
161 passed in an int.
162 This set of bits depend entirely on what kind of provider-side object
164 is passed. For example, those bits are assumed to be the same as those
165 used with provider-keymgmt(7) (see "Key Objects" in
166 provider-keymgmt(7)) when the object is an asymmetric keypair.
167 ENCODER implementations are free to regard the selection as a set of
169 hints, but must do so with care. In the end, the output must make
170 sense, and if there's a corresponding decoder, the resulting decoded
171 object must match the original object that was encoded.
172 OSSL_FUNC_encoder_does_selection() should tell if a particular
174 implementation supports any of the combinations given by selection.
175 Context functions
177 OSSL_FUNC_encoder_newctx() returns a context to be used with the rest
178 of the functions.
179 OSSL_FUNC_encoder_freectx() frees the given ctx, if it was created by
181 OSSL_FUNC_encoder_newctx().
182 OSSL_FUNC_encoder_set_ctx_params() sets context data according to
184 parameters from params that it recognises. Unrecognised parameters
185 should be ignored. Passing NULL for params should return true.
186 OSSL_FUNC_encoder_settable_ctx_params() returns a constant
188 OSSL_PARAM(3) array describing the parameters that
189 OSSL_FUNC_encoder_set_ctx_params() can handle.
190 See OSSL_PARAM(3) for further details on the parameters structure used
192 by OSSL_FUNC_encoder_set_ctx_params() and
193 OSSL_FUNC_encoder_settable_ctx_params().
194 Import functions
196 A provider-native object may be associated with a foreign provider, and
197 may therefore be unsuitable for direct use with a given ENCODER
198 implementation. Provided that the foreign provider's implementation to
199 handle the object has a function to export that object in OSSL_PARAM(3)
200 array form, the ENCODER implementation should be able to import that
201 array and create a suitable object to be passed to
202 OSSL_FUNC_encoder_encode()'s obj_raw.
203 OSSL_FUNC_encoder_import_object() should import the subset of params
205 given with selection to create a provider-native object that can be
206 passed as obj_raw to OSSL_FUNC_encoder_encode().
207 OSSL_FUNC_encoder_free_object() should free the object that was created
209 with OSSL_FUNC_encoder_import_object().
210 Encoding functions
212 OSSL_FUNC_encoder_encode() should take a provider-native object (in
213 obj_raw) or an object abstraction (in obj_abstract), and should output
214 the object in encoded form to the OSSL_CORE_BIO. The selection bits,
215 if relevant, should determine in greater detail what will be output.
216 The encoding functions also take an OSSL_PASSPHRASE_CALLBACK(3)
217 function pointer along with a pointer to application data cbarg, which
218 should be used when a pass phrase prompt is needed.
219 Encoder operation parameters
221 Operation parameters currently recognised by built-in encoders are as
222 follows:
223 "cipher" (OSSL_ENCODER_PARAM_CIPHER) <UTF8 string>
225 The name of the encryption cipher to be used when generating
226 encrypted encoding. This is used when encoding private keys, as
227 well as other objects that need protection.
228 If this name is invalid for the encoding implementation, the
230 implementation should refuse to perform the encoding, i.e.
231 OSSL_FUNC_encoder_encode_data() and
232 OSSL_FUNC_encoder_encode_object() should return an error.
233 "properties" (OSSL_ENCODER_PARAM_PROPERTIES) <UTF8 string>
235 The properties to be queried when trying to fetch the algorithm
236 given with the "cipher" parameter. This must be given together
237 with the "cipher" parameter to be considered valid.
238 The encoding implementation isn't obligated to use this value.
240 However, it is recommended that implementations that do not handle
241 property strings return an error on receiving this parameter unless
242 its value NULL or the empty string.
243 "save-parameters" (OSSL_ENCODER_PARAM_SAVE_PARAMETERS) <integer>
245 If set to 0 disables saving of key domain parameters. Default is 1.
246 It currently has an effect only on DSA keys.
247 Parameters currently recognised by the built-in pass phrase callback:
249 "info" (OSSL_PASSPHRASE_PARAM_INFO) <UTF8 string>
251 A string of information that will become part of the pass phrase
252 prompt. This could be used to give the user information on what
253 kind of object it's being prompted for.
254
256 OSSL_FUNC_encoder_newctx() returns a pointer to a context, or NULL on
257 failure.
258 OSSL_FUNC_encoder_set_ctx_params() returns 1, unless a recognised
260 parameter was invalid or caused an error, for which 0 is returned.
261 OSSL_FUNC_encoder_settable_ctx_params() returns a pointer to an array
263 of constant OSSL_PARAM(3) elements.
264 OSSL_FUNC_encoder_does_selection() returns 1 if the encoder
266 implementation supports any of the selection bits, otherwise 0.
267 OSSL_FUNC_encoder_encode() returns 1 on success, or 0 on failure.
269
271 provider(7)
272
274 The ENCODER interface was introduced in OpenSSL 3.0.
275
277 Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
278 Licensed under the Apache License 2.0 (the "License"). You may not use
280 this file except in compliance with the License. You can obtain a copy
281 in the file LICENSE in the source distribution or at
282 <https://www.openssl.org/source/license.html>.
2833.0.9 2023-07-27 PROVIDER-ENCODER(7ossl)