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 arrays via OSSL_ALGORITHM
73 arrays that are returned by the provider's provider_query_operation()
74 function (see "Provider Functions" in provider-base(7)).
75 All these "functions" have a corresponding function type definition
77 named OSSL_FUNC_{name}_fn, and a helper function to retrieve the
78 function pointer from an OSSL_DISPATCH element named OSSL_FUNC_{name}.
79 For example, the "function" OSSL_FUNC_encoder_encode() has these:
80 typedef int
82 (OSSL_FUNC_encoder_encode_fn)(void *ctx, OSSL_CORE_BIO *out,
83 const void *obj_raw,
84 const OSSL_PARAM obj_abstract[],
85 int selection,
86 OSSL_PASSPHRASE_CALLBACK *cb, void *cbarg);
87 static ossl_inline OSSL_FUNC_encoder_encode_fn
88 OSSL_FUNC_encoder_encode(const OSSL_DISPATCH *opf);
89 OSSL_DISPATCH arrays are indexed by numbers that are provided as macros
91 in openssl-core_dispatch.h(7), as follows:
92 OSSL_FUNC_encoder_get_params OSSL_FUNC_ENCODER_GET_PARAMS
94 OSSL_FUNC_encoder_gettable_params OSSL_FUNC_ENCODER_GETTABLE_PARAMS
95 OSSL_FUNC_encoder_newctx OSSL_FUNC_ENCODER_NEWCTX
97 OSSL_FUNC_encoder_freectx OSSL_FUNC_ENCODER_FREECTX
98 OSSL_FUNC_encoder_set_ctx_params OSSL_FUNC_ENCODER_SET_CTX_PARAMS
99 OSSL_FUNC_encoder_settable_ctx_params OSSL_FUNC_ENCODER_SETTABLE_CTX_PARAMS
100 OSSL_FUNC_encoder_does_selection OSSL_FUNC_ENCODER_DOES_SELECTION
102 OSSL_FUNC_encoder_encode OSSL_FUNC_ENCODER_ENCODE
104 OSSL_FUNC_encoder_import_object OSSL_FUNC_ENCODER_IMPORT_OBJECT
106 OSSL_FUNC_encoder_free_object OSSL_FUNC_ENCODER_FREE_OBJECT
107 Names and properties
109 The name of an implementation should match the type of object it
110 handles. For example, an implementation that encodes an RSA key should
111 be named "RSA". Likewise, an implementation that further encodes DER
112 should be named "DER".
113 Properties can be used to further specify details about an
115 implementation:
116 output
118 This property is used to specify what type of output the
119 implementation produces.
120 This property is mandatory.
122 OpenSSL providers recognize the following output types:
124 text
126 An implementation with that output type outputs human readable
127 text, making that implementation suitable for "-text" output in
128 diverse openssl(1) commands.
129 pem An implementation with that output type outputs PEM formatted
131 data.
132 der An implementation with that output type outputs DER formatted
134 data.
135 msblob
137 An implementation with that output type outputs MSBLOB
138 formatted data.
139 pvk An implementation with that output type outputs PVK formatted
141 data.
142 structure
144 This property is used to specify the structure that is used for the
145 encoded object. An example could be "pkcs8", to specify explicitly
146 that an object (presumably an asymmetric key pair, in this case)
147 will be wrapped in a PKCS#8 structure as part of the encoding.
148 This property is optional.
150 The possible values of both these properties is open ended. A provider
152 may very well specify output types and structures that libcrypto
153 doesn't know anything about.
154 Subset selections
156 Sometimes, an object has more than one subset of data that is
157 interesting to treat separately or together. It's possible to specify
158 what subsets are to be encoded, with a set of bits selection that are
159 passed in an int.
160 This set of bits depend entirely on what kind of provider-side object
162 is passed. For example, those bits are assumed to be the same as those
163 used with provider-keymgmt(7) (see "Key Objects" in
164 provider-keymgmt(7)) when the object is an asymmetric keypair.
165 ENCODER implementations are free to regard the selection as a set of
167 hints, but must do so with care. In the end, the output must make
168 sense, and if there's a corresponding decoder, the resulting decoded
169 object must match the original object that was encoded.
170 OSSL_FUNC_encoder_does_selection() should tell if a particular
172 implementation supports any of the combinations given by selection.
173 Context functions
175 OSSL_FUNC_encoder_newctx() returns a context to be used with the rest
176 of the functions.
177 OSSL_FUNC_encoder_freectx() frees the given ctx, if it was created by
179 OSSL_FUNC_encoder_newctx().
180 OSSL_FUNC_encoder_set_ctx_params() sets context data according to
182 parameters from params that it recognises. Unrecognised parameters
183 should be ignored. Passing NULL for params should return true.
184 OSSL_FUNC_encoder_settable_ctx_params() returns a constant OSSL_PARAM
186 array describing the parameters that OSSL_FUNC_encoder_set_ctx_params()
187 can handle.
188 See OSSL_PARAM(3) for further details on the parameters structure used
190 by OSSL_FUNC_encoder_set_ctx_params() and
191 OSSL_FUNC_encoder_settable_ctx_params().
192 Import functions
194 A provider-native object may be associated with a foreign provider, and
195 may therefore be unsuitable for direct use with a given ENCODER
196 implementation. Provided that the foreign provider's implementation to
197 handle the object has a function to export that object in OSSL_PARAM(3)
198 array form, the ENCODER implementation should be able to import that
199 array and create a suitable object to be passed to
200 OSSL_FUNC_encoder_encode()'s obj_raw.
201 OSSL_FUNC_encoder_import_object() should import the subset of params
203 given with selection to create a provider-native object that can be
204 passed as obj_raw to OSSL_FUNC_encoder_encode().
205 OSSL_FUNC_encoder_free_object() should free the object that was created
207 with OSSL_FUNC_encoder_import_object().
208 Encoding functions
210 OSSL_FUNC_encoder_encode() should take a provider-native object (in
211 obj_raw) or an object abstraction (in obj_abstract), and should output
212 the object in encoded form to the OSSL_CORE_BIO. The selection bits,
213 if relevant, should determine in greater detail what will be output.
214 The encoding functions also take an OSSL_PASSPHRASE_CALLBACK function
215 pointer along with a pointer to application data cbarg, which should be
216 used when a pass phrase prompt is needed.
217 Encoder operation parameters
219 Operation parameters currently recognised by built-in encoders are as
220 follows:
221 "cipher" (OSSL_ENCODER_PARAM_CIPHER) <UTF8 string>
223 The name of the encryption cipher to be used when generating
224 encrypted encoding. This is used when encoding private keys, as
225 well as other objects that need protection.
226 If this name is invalid for the encoding implementation, the
228 implementation should refuse to perform the encoding, i.e.
229 OSSL_FUNC_encoder_encode_data() and
230 OSSL_FUNC_encoder_encode_object() should return an error.
231 "properties" (OSSL_ENCODER_PARAM_PROPERTIES) <UTF8 string>
233 The properties to be queried when trying to fetch the algorithm
234 given with the "cipher" parameter. This must be given together
235 with the "cipher" parameter to be considered valid.
236 The encoding implementation isn't obligated to use this value.
238 However, it is recommended that implementations that do not handle
239 property strings return an error on receiving this parameter unless
240 its value NULL or the empty string.
241 "save-parameters" (OSSL_ENCODER_PARAM_SAVE_PARAMETERS) <integer>
243 If set to 0 disables saving of key domain parameters. Default is 1.
244 It currently has an effect only on DSA keys.
245 Parameters currently recognised by the built-in pass phrase callback:
247 "info" (OSSL_PASSPHRASE_PARAM_INFO) <UTF8 string>
249 A string of information that will become part of the pass phrase
250 prompt. This could be used to give the user information on what
251 kind of object it's being prompted for.
252
254 OSSL_FUNC_encoder_newctx() returns a pointer to a context, or NULL on
255 failure.
256 OSSL_FUNC_encoder_set_ctx_params() returns 1, unless a recognised
258 parameter was invalid or caused an error, for which 0 is returned.
259 OSSL_FUNC_encoder_settable_ctx_params() returns a pointer to an array
261 of constant OSSL_PARAM elements.
262 OSSL_FUNC_encoder_does_selection() returns 1 if the encoder
264 implementation supports any of the selection bits, otherwise 0.
265 OSSL_FUNC_encoder_encode() returns 1 on success, or 0 on failure.
267
269 provider(7)
270
272 The ENCODER interface was introduced in OpenSSL 3.0.
273
275 Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
276 Licensed under the Apache License 2.0 (the "License"). You may not use
278 this file except in compliance with the License. You can obtain a copy
279 in the file LICENSE in the source distribution or at
280 <https://www.openssl.org/source/license.html>.
2813.0.5 2022-07-05 PROVIDER-ENCODER(7ossl)