1ENGINE_ADD(3ossl) OpenSSL ENGINE_ADD(3ossl)
2
6 ENGINE_get_DH, ENGINE_get_DSA, ENGINE_by_id, ENGINE_get_cipher_engine,
7 ENGINE_get_default_DH, ENGINE_get_default_DSA, ENGINE_get_default_RAND,
8 ENGINE_get_default_RSA, ENGINE_get_digest_engine, ENGINE_get_first,
9 ENGINE_get_last, ENGINE_get_next, ENGINE_get_prev, ENGINE_new,
10 ENGINE_get_ciphers, ENGINE_get_ctrl_function, ENGINE_get_digests,
11 ENGINE_get_destroy_function, ENGINE_get_finish_function,
12 ENGINE_get_init_function, ENGINE_get_load_privkey_function,
13 ENGINE_get_load_pubkey_function, ENGINE_load_private_key,
14 ENGINE_load_public_key, ENGINE_get_RAND, ENGINE_get_RSA, ENGINE_get_id,
15 ENGINE_get_name, ENGINE_get_cmd_defns, ENGINE_get_cipher,
16 ENGINE_get_digest, ENGINE_add, ENGINE_cmd_is_executable, ENGINE_ctrl,
17 ENGINE_ctrl_cmd, ENGINE_ctrl_cmd_string, ENGINE_finish, ENGINE_free,
18 ENGINE_get_flags, ENGINE_init, ENGINE_register_DH, ENGINE_register_DSA,
19 ENGINE_register_RAND, ENGINE_register_RSA,
20 ENGINE_register_all_complete, ENGINE_register_ciphers,
21 ENGINE_register_complete, ENGINE_register_digests, ENGINE_remove,
22 ENGINE_set_DH, ENGINE_set_DSA, ENGINE_set_RAND, ENGINE_set_RSA,
23 ENGINE_set_ciphers, ENGINE_set_cmd_defns, ENGINE_set_ctrl_function,
24 ENGINE_set_default, ENGINE_set_default_DH, ENGINE_set_default_DSA,
25 ENGINE_set_default_RAND, ENGINE_set_default_RSA,
26 ENGINE_set_default_ciphers, ENGINE_set_default_digests,
27 ENGINE_set_default_string, ENGINE_set_destroy_function,
28 ENGINE_set_digests, ENGINE_set_finish_function, ENGINE_set_flags,
29 ENGINE_set_id, ENGINE_set_init_function,
30 ENGINE_set_load_privkey_function, ENGINE_set_load_pubkey_function,
31 ENGINE_set_name, ENGINE_up_ref, ENGINE_get_table_flags, ENGINE_cleanup,
32 ENGINE_load_builtin_engines, ENGINE_register_all_DH,
33 ENGINE_register_all_DSA, ENGINE_register_all_RAND,
34 ENGINE_register_all_RSA, ENGINE_register_all_ciphers,
35 ENGINE_register_all_digests, ENGINE_set_table_flags,
36 ENGINE_unregister_DH, ENGINE_unregister_DSA, ENGINE_unregister_RAND,
37 ENGINE_unregister_RSA, ENGINE_unregister_ciphers,
38 ENGINE_unregister_digests - ENGINE cryptographic module support
39
41 #include <openssl/engine.h>
42 The following functions have been deprecated since OpenSSL 3.0, and can
44 be hidden entirely by defining OPENSSL_API_COMPAT with a suitable
45 version value, see openssl_user_macros(7):
46 ENGINE *ENGINE_get_first(void);
48 ENGINE *ENGINE_get_last(void);
49 ENGINE *ENGINE_get_next(ENGINE *e);
50 ENGINE *ENGINE_get_prev(ENGINE *e);
51 int ENGINE_add(ENGINE *e);
53 int ENGINE_remove(ENGINE *e);
54 ENGINE *ENGINE_by_id(const char *id);
56 int ENGINE_init(ENGINE *e);
58 int ENGINE_finish(ENGINE *e);
59 void ENGINE_load_builtin_engines(void);
61 ENGINE *ENGINE_get_default_RSA(void);
63 ENGINE *ENGINE_get_default_DSA(void);
64 ENGINE *ENGINE_get_default_DH(void);
65 ENGINE *ENGINE_get_default_RAND(void);
66 ENGINE *ENGINE_get_cipher_engine(int nid);
67 ENGINE *ENGINE_get_digest_engine(int nid);
68 int ENGINE_set_default_RSA(ENGINE *e);
70 int ENGINE_set_default_DSA(ENGINE *e);
71 int ENGINE_set_default_DH(ENGINE *e);
72 int ENGINE_set_default_RAND(ENGINE *e);
73 int ENGINE_set_default_ciphers(ENGINE *e);
74 int ENGINE_set_default_digests(ENGINE *e);
75 int ENGINE_set_default_string(ENGINE *e, const char *list);
76 int ENGINE_set_default(ENGINE *e, unsigned int flags);
78 unsigned int ENGINE_get_table_flags(void);
80 void ENGINE_set_table_flags(unsigned int flags);
81 int ENGINE_register_RSA(ENGINE *e);
83 void ENGINE_unregister_RSA(ENGINE *e);
84 void ENGINE_register_all_RSA(void);
85 int ENGINE_register_DSA(ENGINE *e);
86 void ENGINE_unregister_DSA(ENGINE *e);
87 void ENGINE_register_all_DSA(void);
88 int ENGINE_register_DH(ENGINE *e);
89 void ENGINE_unregister_DH(ENGINE *e);
90 void ENGINE_register_all_DH(void);
91 int ENGINE_register_RAND(ENGINE *e);
92 void ENGINE_unregister_RAND(ENGINE *e);
93 void ENGINE_register_all_RAND(void);
94 int ENGINE_register_ciphers(ENGINE *e);
95 void ENGINE_unregister_ciphers(ENGINE *e);
96 void ENGINE_register_all_ciphers(void);
97 int ENGINE_register_digests(ENGINE *e);
98 void ENGINE_unregister_digests(ENGINE *e);
99 void ENGINE_register_all_digests(void);
100 int ENGINE_register_complete(ENGINE *e);
101 int ENGINE_register_all_complete(void);
102 int ENGINE_ctrl(ENGINE *e, int cmd, long i, void *p, void (*f)(void));
104 int ENGINE_cmd_is_executable(ENGINE *e, int cmd);
105 int ENGINE_ctrl_cmd(ENGINE *e, const char *cmd_name,
106 long i, void *p, void (*f)(void), int cmd_optional);
107 int ENGINE_ctrl_cmd_string(ENGINE *e, const char *cmd_name, const char *arg,
108 int cmd_optional);
109 ENGINE *ENGINE_new(void);
111 int ENGINE_free(ENGINE *e);
112 int ENGINE_up_ref(ENGINE *e);
113 int ENGINE_set_id(ENGINE *e, const char *id);
115 int ENGINE_set_name(ENGINE *e, const char *name);
116 int ENGINE_set_RSA(ENGINE *e, const RSA_METHOD *rsa_meth);
117 int ENGINE_set_DSA(ENGINE *e, const DSA_METHOD *dsa_meth);
118 int ENGINE_set_DH(ENGINE *e, const DH_METHOD *dh_meth);
119 int ENGINE_set_RAND(ENGINE *e, const RAND_METHOD *rand_meth);
120 int ENGINE_set_destroy_function(ENGINE *e, ENGINE_GEN_INT_FUNC_PTR destroy_f);
121 int ENGINE_set_init_function(ENGINE *e, ENGINE_GEN_INT_FUNC_PTR init_f);
122 int ENGINE_set_finish_function(ENGINE *e, ENGINE_GEN_INT_FUNC_PTR finish_f);
123 int ENGINE_set_ctrl_function(ENGINE *e, ENGINE_CTRL_FUNC_PTR ctrl_f);
124 int ENGINE_set_load_privkey_function(ENGINE *e, ENGINE_LOAD_KEY_PTR loadpriv_f);
125 int ENGINE_set_load_pubkey_function(ENGINE *e, ENGINE_LOAD_KEY_PTR loadpub_f);
126 int ENGINE_set_ciphers(ENGINE *e, ENGINE_CIPHERS_PTR f);
127 int ENGINE_set_digests(ENGINE *e, ENGINE_DIGESTS_PTR f);
128 int ENGINE_set_flags(ENGINE *e, int flags);
129 int ENGINE_set_cmd_defns(ENGINE *e, const ENGINE_CMD_DEFN *defns);
130 const char *ENGINE_get_id(const ENGINE *e);
132 const char *ENGINE_get_name(const ENGINE *e);
133 const RSA_METHOD *ENGINE_get_RSA(const ENGINE *e);
134 const DSA_METHOD *ENGINE_get_DSA(const ENGINE *e);
135 const DH_METHOD *ENGINE_get_DH(const ENGINE *e);
136 const RAND_METHOD *ENGINE_get_RAND(const ENGINE *e);
137 ENGINE_GEN_INT_FUNC_PTR ENGINE_get_destroy_function(const ENGINE *e);
138 ENGINE_GEN_INT_FUNC_PTR ENGINE_get_init_function(const ENGINE *e);
139 ENGINE_GEN_INT_FUNC_PTR ENGINE_get_finish_function(const ENGINE *e);
140 ENGINE_CTRL_FUNC_PTR ENGINE_get_ctrl_function(const ENGINE *e);
141 ENGINE_LOAD_KEY_PTR ENGINE_get_load_privkey_function(const ENGINE *e);
142 ENGINE_LOAD_KEY_PTR ENGINE_get_load_pubkey_function(const ENGINE *e);
143 ENGINE_CIPHERS_PTR ENGINE_get_ciphers(const ENGINE *e);
144 ENGINE_DIGESTS_PTR ENGINE_get_digests(const ENGINE *e);
145 const EVP_CIPHER *ENGINE_get_cipher(ENGINE *e, int nid);
146 const EVP_MD *ENGINE_get_digest(ENGINE *e, int nid);
147 int ENGINE_get_flags(const ENGINE *e);
148 const ENGINE_CMD_DEFN *ENGINE_get_cmd_defns(const ENGINE *e);
149 EVP_PKEY *ENGINE_load_private_key(ENGINE *e, const char *key_id,
151 UI_METHOD *ui_method, void *callback_data);
152 EVP_PKEY *ENGINE_load_public_key(ENGINE *e, const char *key_id,
153 UI_METHOD *ui_method, void *callback_data);
154 The following function has been deprecated since OpenSSL 1.1.0, and can
156 be hidden entirely by defining OPENSSL_API_COMPAT with a suitable
157 version value, see openssl_user_macros(7):
158 void ENGINE_cleanup(void);
160
162 All of the functions described on this page are deprecated.
163 Applications should instead use the provider APIs.
164 These functions create, manipulate, and use cryptographic modules in
166 the form of ENGINE objects. These objects act as containers for
167 implementations of cryptographic algorithms, and support a reference-
168 counted mechanism to allow them to be dynamically loaded in and out of
169 the running application.
170 The cryptographic functionality that can be provided by an ENGINE
172 implementation includes the following abstractions;
173 RSA_METHOD - for providing alternative RSA implementations
175 DSA_METHOD, DH_METHOD, RAND_METHOD, ECDH_METHOD, ECDSA_METHOD,
176 - similarly for other OpenSSL APIs
177 EVP_CIPHER - potentially multiple cipher algorithms (indexed by 'nid')
178 EVP_DIGEST - potentially multiple hash algorithms (indexed by 'nid')
179 key-loading - loading public and/or private EVP_PKEY keys
180 Reference counting and handles
182 Due to the modular nature of the ENGINE API, pointers to ENGINEs need
183 to be treated as handles - i.e. not only as pointers, but also as
184 references to the underlying ENGINE object. Ie. one should obtain a new
185 reference when making copies of an ENGINE pointer if the copies will be
186 used (and released) independently.
187 ENGINE objects have two levels of reference-counting to match the way
189 in which the objects are used. At the most basic level, each ENGINE
190 pointer is inherently a structural reference - a structural reference
191 is required to use the pointer value at all, as this kind of reference
192 is a guarantee that the structure can not be deallocated until the
193 reference is released.
194 However, a structural reference provides no guarantee that the ENGINE
196 is initialised and able to use any of its cryptographic
197 implementations. Indeed it's quite possible that most ENGINEs will not
198 initialise at all in typical environments, as ENGINEs are typically
199 used to support specialised hardware. To use an ENGINE's functionality,
200 you need a functional reference. This kind of reference can be
201 considered a specialised form of structural reference, because each
202 functional reference implicitly contains a structural reference as well
203 - however to avoid difficult-to-find programming bugs, it is
204 recommended to treat the two kinds of reference independently. If you
205 have a functional reference to an ENGINE, you have a guarantee that the
206 ENGINE has been initialised and is ready to perform cryptographic
207 operations, and will remain initialised until after you have released
208 your reference.
209 Structural references
211 This basic type of reference is used for instantiating new ENGINEs,
213 iterating across OpenSSL's internal linked-list of loaded ENGINEs,
214 reading information about an ENGINE, etc. Essentially a structural
215 reference is sufficient if you only need to query or manipulate the
216 data of an ENGINE implementation rather than use its functionality.
217 The ENGINE_new() function returns a structural reference to a new
219 (empty) ENGINE object. There are other ENGINE API functions that return
220 structural references such as; ENGINE_by_id(), ENGINE_get_first(),
221 ENGINE_get_last(), ENGINE_get_next(), ENGINE_get_prev(). All structural
222 references should be released by a corresponding to call to the
223 ENGINE_free() function - the ENGINE object itself will only actually be
224 cleaned up and deallocated when the last structural reference is
225 released.
226 It should also be noted that many ENGINE API function calls that accept
228 a structural reference will internally obtain another reference -
229 typically this happens whenever the supplied ENGINE will be needed by
230 OpenSSL after the function has returned. Eg. the function to add a new
231 ENGINE to OpenSSL's internal list is ENGINE_add() - if this function
232 returns success, then OpenSSL will have stored a new structural
233 reference internally so the caller is still responsible for freeing
234 their own reference with ENGINE_free() when they are finished with it.
235 In a similar way, some functions will automatically release the
236 structural reference passed to it if part of the function's job is to
237 do so. Eg. the ENGINE_get_next() and ENGINE_get_prev() functions are
238 used for iterating across the internal ENGINE list - they will return a
239 new structural reference to the next (or previous) ENGINE in the list
240 or NULL if at the end (or beginning) of the list, but in either case
241 the structural reference passed to the function is released on behalf
242 of the caller.
243 To clarify a particular function's handling of references, one should
245 always consult that function's documentation "man" page, or failing
246 that the <openssl/engine.h> header file includes some hints.
247 Functional references
249 As mentioned, functional references exist when the cryptographic
251 functionality of an ENGINE is required to be available. A functional
252 reference can be obtained in one of two ways; from an existing
253 structural reference to the required ENGINE, or by asking OpenSSL for
254 the default operational ENGINE for a given cryptographic purpose.
255 To obtain a functional reference from an existing structural reference,
257 call the ENGINE_init() function. This returns zero if the ENGINE was
258 not already operational and couldn't be successfully initialised (e.g.
259 lack of system drivers, no special hardware attached, etc), otherwise
260 it will return nonzero to indicate that the ENGINE is now operational
261 and will have allocated a new functional reference to the ENGINE. All
262 functional references are released by calling ENGINE_finish() (which
263 removes the implicit structural reference as well).
264 The second way to get a functional reference is by asking OpenSSL for a
266 default implementation for a given task, e.g. by
267 ENGINE_get_default_RSA(), ENGINE_get_default_cipher_engine(), etc.
268 These are discussed in the next section, though they are not usually
269 required by application programmers as they are used automatically when
270 creating and using the relevant algorithm-specific types in OpenSSL,
271 such as RSA, DSA, EVP_CIPHER_CTX, etc.
272 Default implementations
274 For each supported abstraction, the ENGINE code maintains an internal
275 table of state to control which implementations are available for a
276 given abstraction and which should be used by default. These
277 implementations are registered in the tables and indexed by an 'nid'
278 value, because abstractions like EVP_CIPHER and EVP_DIGEST support many
279 distinct algorithms and modes, and ENGINEs can support arbitrarily many
280 of them. In the case of other abstractions like RSA, DSA, etc, there
281 is only one "algorithm" so all implementations implicitly register
282 using the same 'nid' index.
283 When a default ENGINE is requested for a given
285 abstraction/algorithm/mode, (e.g. when calling RSA_new_method(NULL)),
286 a "get_default" call will be made to the ENGINE subsystem to process
287 the corresponding state table and return a functional reference to an
288 initialised ENGINE whose implementation should be used. If no ENGINE
289 should (or can) be used, it will return NULL and the caller will
290 operate with a NULL ENGINE handle - this usually equates to using the
291 conventional software implementation. In the latter case, OpenSSL will
292 from then on behave the way it used to before the ENGINE API existed.
293 Each state table has a flag to note whether it has processed this
295 "get_default" query since the table was last modified, because to
296 process this question it must iterate across all the registered ENGINEs
297 in the table trying to initialise each of them in turn, in case one of
298 them is operational. If it returns a functional reference to an ENGINE,
299 it will also cache another reference to speed up processing future
300 queries (without needing to iterate across the table). Likewise, it
301 will cache a NULL response if no ENGINE was available so that future
302 queries won't repeat the same iteration unless the state table changes.
303 This behaviour can also be changed; if the ENGINE_TABLE_FLAG_NOINIT
304 flag is set (using ENGINE_set_table_flags()), no attempted
305 initialisations will take place, instead the only way for the state
306 table to return a non-NULL ENGINE to the "get_default" query will be if
307 one is expressly set in the table. Eg. ENGINE_set_default_RSA() does
308 the same job as ENGINE_register_RSA() except that it also sets the
309 state table's cached response for the "get_default" query. In the case
310 of abstractions like EVP_CIPHER, where implementations are indexed by
311 'nid', these flags and cached-responses are distinct for each 'nid'
312 value.
313 Application requirements
315 This section will explain the basic things an application programmer
316 should support to make the most useful elements of the ENGINE
317 functionality available to the user. The first thing to consider is
318 whether the programmer wishes to make alternative ENGINE modules
319 available to the application and user. OpenSSL maintains an internal
320 linked list of "visible" ENGINEs from which it has to operate - at
321 start-up, this list is empty and in fact if an application does not
322 call any ENGINE API calls and it uses static linking against openssl,
323 then the resulting application binary will not contain any alternative
324 ENGINE code at all. So the first consideration is whether any/all
325 available ENGINE implementations should be made visible to OpenSSL -
326 this is controlled by calling the various "load" functions.
327 The fact that ENGINEs are made visible to OpenSSL (and thus are linked
329 into the program and loaded into memory at run-time) does not mean they
330 are "registered" or called into use by OpenSSL automatically - that
331 behaviour is something for the application to control. Some
332 applications will want to allow the user to specify exactly which
333 ENGINE they want used if any is to be used at all. Others may prefer to
334 load all support and have OpenSSL automatically use at run-time any
335 ENGINE that is able to successfully initialise - i.e. to assume that
336 this corresponds to acceleration hardware attached to the machine or
337 some such thing. There are probably numerous other ways in which
338 applications may prefer to handle things, so we will simply illustrate
339 the consequences as they apply to a couple of simple cases and leave
340 developers to consider these and the source code to openssl's built-in
341 utilities as guides.
342 If no ENGINE API functions are called within an application, then
344 OpenSSL will not allocate any internal resources. Prior to OpenSSL
345 1.1.0, however, if any ENGINEs are loaded, even if not registered or
346 used, it was necessary to call ENGINE_cleanup() before the program
347 exits.
348 Using a specific ENGINE implementation
350 Here we'll assume an application has been configured by its user or
352 admin to want to use the "ACME" ENGINE if it is available in the
353 version of OpenSSL the application was compiled with. If it is
354 available, it should be used by default for all RSA, DSA, and symmetric
355 cipher operations, otherwise OpenSSL should use its built-in software
356 as per usual. The following code illustrates how to approach this;
357 ENGINE *e;
359 const char *engine_id = "ACME";
360 ENGINE_load_builtin_engines();
361 e = ENGINE_by_id(engine_id);
362 if (!e)
363 /* the engine isn't available */
364 return;
365 if (!ENGINE_init(e)) {
366 /* the engine couldn't initialise, release 'e' */
367 ENGINE_free(e);
368 return;
369 }
370 if (!ENGINE_set_default_RSA(e))
371 /*
372 * This should only happen when 'e' can't initialise, but the previous
373 * statement suggests it did.
374 */
375 abort();
376 ENGINE_set_default_DSA(e);
377 ENGINE_set_default_ciphers(e);
378 /* Release the functional reference from ENGINE_init() */
379 ENGINE_finish(e);
380 /* Release the structural reference from ENGINE_by_id() */
381 ENGINE_free(e);
382 Automatically using built-in ENGINE implementations
384 Here we'll assume we want to load and register all ENGINE
386 implementations bundled with OpenSSL, such that for any cryptographic
387 algorithm required by OpenSSL - if there is an ENGINE that implements
388 it and can be initialised, it should be used. The following code
389 illustrates how this can work;
390 /* Load all bundled ENGINEs into memory and make them visible */
392 ENGINE_load_builtin_engines();
393 /* Register all of them for every algorithm they collectively implement */
394 ENGINE_register_all_complete();
395 That's all that's required. Eg. the next time OpenSSL tries to set up
397 an RSA key, any bundled ENGINEs that implement RSA_METHOD will be
398 passed to ENGINE_init() and if any of those succeed, that ENGINE will
399 be set as the default for RSA use from then on.
400 Advanced configuration support
402 There is a mechanism supported by the ENGINE framework that allows each
403 ENGINE implementation to define an arbitrary set of configuration
404 "commands" and expose them to OpenSSL and any applications based on
405 OpenSSL. This mechanism is entirely based on the use of name-value
406 pairs and assumes ASCII input (no unicode or UTF for now!), so it is
407 ideal if applications want to provide a transparent way for users to
408 provide arbitrary configuration "directives" directly to such ENGINEs.
409 It is also possible for the application to dynamically interrogate the
410 loaded ENGINE implementations for the names, descriptions, and input
411 flags of their available "control commands", providing a more flexible
412 configuration scheme. However, if the user is expected to know which
413 ENGINE device he/she is using (in the case of specialised hardware,
414 this goes without saying) then applications may not need to concern
415 themselves with discovering the supported control commands and simply
416 prefer to pass settings into ENGINEs exactly as they are provided by
417 the user.
418 Before illustrating how control commands work, it is worth mentioning
420 what they are typically used for. Broadly speaking there are two uses
421 for control commands; the first is to provide the necessary details to
422 the implementation (which may know nothing at all specific to the host
423 system) so that it can be initialised for use. This could include the
424 path to any driver or config files it needs to load, required network
425 addresses, smart-card identifiers, passwords to initialise protected
426 devices, logging information, etc etc. This class of commands typically
427 needs to be passed to an ENGINE before attempting to initialise it,
428 i.e. before calling ENGINE_init(). The other class of commands consist
429 of settings or operations that tweak certain behaviour or cause certain
430 operations to take place, and these commands may work either before or
431 after ENGINE_init(), or in some cases both. ENGINE implementations
432 should provide indications of this in the descriptions attached to
433 built-in control commands and/or in external product documentation.
434 Issuing control commands to an ENGINE
436 Let's illustrate by example; a function for which the caller supplies
438 the name of the ENGINE it wishes to use, a table of string-pairs for
439 use before initialisation, and another table for use after
440 initialisation. Note that the string-pairs used for control commands
441 consist of a command "name" followed by the command "parameter" - the
442 parameter could be NULL in some cases but the name can not. This
443 function should initialise the ENGINE (issuing the "pre" commands
444 beforehand and the "post" commands afterwards) and set it as the
445 default for everything except RAND and then return a boolean success or
446 failure.
447 int generic_load_engine_fn(const char *engine_id,
449 const char **pre_cmds, int pre_num,
450 const char **post_cmds, int post_num)
451 {
452 ENGINE *e = ENGINE_by_id(engine_id);
453 if (!e) return 0;
454 while (pre_num--) {
455 if (!ENGINE_ctrl_cmd_string(e, pre_cmds[0], pre_cmds[1], 0)) {
456 fprintf(stderr, "Failed command (%s - %s:%s)\n", engine_id,
457 pre_cmds[0], pre_cmds[1] ? pre_cmds[1] : "(NULL)");
458 ENGINE_free(e);
459 return 0;
460 }
461 pre_cmds += 2;
462 }
463 if (!ENGINE_init(e)) {
464 fprintf(stderr, "Failed initialisation\n");
465 ENGINE_free(e);
466 return 0;
467 }
468 /*
469 * ENGINE_init() returned a functional reference, so free the structural
470 * reference from ENGINE_by_id().
471 */
472 ENGINE_free(e);
473 while (post_num--) {
474 if (!ENGINE_ctrl_cmd_string(e, post_cmds[0], post_cmds[1], 0)) {
475 fprintf(stderr, "Failed command (%s - %s:%s)\n", engine_id,
476 post_cmds[0], post_cmds[1] ? post_cmds[1] : "(NULL)");
477 ENGINE_finish(e);
478 return 0;
479 }
480 post_cmds += 2;
481 }
482 ENGINE_set_default(e, ENGINE_METHOD_ALL & ~ENGINE_METHOD_RAND);
483 /* Success */
484 return 1;
485 }
486 Note that ENGINE_ctrl_cmd_string() accepts a boolean argument that can
488 relax the semantics of the function - if set nonzero it will only
489 return failure if the ENGINE supported the given command name but
490 failed while executing it, if the ENGINE doesn't support the command
491 name it will simply return success without doing anything. In this case
492 we assume the user is only supplying commands specific to the given
493 ENGINE so we set this to FALSE.
494 Discovering supported control commands
496 It is possible to discover at run-time the names, numerical-ids,
498 descriptions and input parameters of the control commands supported by
499 an ENGINE using a structural reference. Note that some control commands
500 are defined by OpenSSL itself and it will intercept and handle these
501 control commands on behalf of the ENGINE, i.e. the ENGINE's ctrl()
502 handler is not used for the control command. <openssl/engine.h>
503 defines an index, ENGINE_CMD_BASE, that all control commands
504 implemented by ENGINEs should be numbered from. Any command value lower
505 than this symbol is considered a "generic" command is handled directly
506 by the OpenSSL core routines.
507 It is using these "core" control commands that one can discover the
509 control commands implemented by a given ENGINE, specifically the
510 commands:
511 ENGINE_HAS_CTRL_FUNCTION
513 ENGINE_CTRL_GET_FIRST_CMD_TYPE
514 ENGINE_CTRL_GET_NEXT_CMD_TYPE
515 ENGINE_CTRL_GET_CMD_FROM_NAME
516 ENGINE_CTRL_GET_NAME_LEN_FROM_CMD
517 ENGINE_CTRL_GET_NAME_FROM_CMD
518 ENGINE_CTRL_GET_DESC_LEN_FROM_CMD
519 ENGINE_CTRL_GET_DESC_FROM_CMD
520 ENGINE_CTRL_GET_CMD_FLAGS
521 Whilst these commands are automatically processed by the OpenSSL
523 framework code, they use various properties exposed by each ENGINE to
524 process these queries. An ENGINE has 3 properties it exposes that can
525 affect how this behaves; it can supply a ctrl() handler, it can specify
526 ENGINE_FLAGS_MANUAL_CMD_CTRL in the ENGINE's flags, and it can expose
527 an array of control command descriptions. If an ENGINE specifies the
528 ENGINE_FLAGS_MANUAL_CMD_CTRL flag, then it will simply pass all these
529 "core" control commands directly to the ENGINE's ctrl() handler (and
530 thus, it must have supplied one), so it is up to the ENGINE to reply to
531 these "discovery" commands itself. If that flag is not set, then the
532 OpenSSL framework code will work with the following rules:
533 if no ctrl() handler supplied;
535 ENGINE_HAS_CTRL_FUNCTION returns FALSE (zero),
536 all other commands fail.
537 if a ctrl() handler was supplied but no array of control commands;
538 ENGINE_HAS_CTRL_FUNCTION returns TRUE,
539 all other commands fail.
540 if a ctrl() handler and array of control commands was supplied;
541 ENGINE_HAS_CTRL_FUNCTION returns TRUE,
542 all other commands proceed processing ...
543 If the ENGINE's array of control commands is empty then all other
545 commands will fail, otherwise; ENGINE_CTRL_GET_FIRST_CMD_TYPE returns
546 the identifier of the first command supported by the ENGINE,
547 ENGINE_GET_NEXT_CMD_TYPE takes the identifier of a command supported by
548 the ENGINE and returns the next command identifier or fails if there
549 are no more, ENGINE_CMD_FROM_NAME takes a string name for a command and
550 returns the corresponding identifier or fails if no such command name
551 exists, and the remaining commands take a command identifier and return
552 properties of the corresponding commands. All except
553 ENGINE_CTRL_GET_FLAGS return the string length of a command name or
554 description, or populate a supplied character buffer with a copy of the
555 command name or description. ENGINE_CTRL_GET_FLAGS returns a bitwise-
556 OR'd mask of the following possible values:
557 ENGINE_CMD_FLAG_NUMERIC
559 ENGINE_CMD_FLAG_STRING
560 ENGINE_CMD_FLAG_NO_INPUT
561 ENGINE_CMD_FLAG_INTERNAL
562 If the ENGINE_CMD_FLAG_INTERNAL flag is set, then any other flags are
564 purely informational to the caller - this flag will prevent the command
565 being usable for any higher-level ENGINE functions such as
566 ENGINE_ctrl_cmd_string(). "INTERNAL" commands are not intended to be
567 exposed to text-based configuration by applications, administrations,
568 users, etc. These can support arbitrary operations via ENGINE_ctrl(),
569 including passing to and/or from the control commands data of any
570 arbitrary type. These commands are supported in the discovery
571 mechanisms simply to allow applications to determine if an ENGINE
572 supports certain specific commands it might want to use (e.g.
573 application "foo" might query various ENGINEs to see if they implement
574 "FOO_GET_VENDOR_LOGO_GIF" - and ENGINE could therefore decide whether
575 or not to support this "foo"-specific extension).
576
578 OPENSSL_ENGINES
579 The path to the engines directory. Ignored in set-user-ID and set-
580 group-ID programs.
581
583 ENGINE_get_first(), ENGINE_get_last(), ENGINE_get_next() and
584 ENGINE_get_prev() return a valid ENGINE structure or NULL if an error
585 occurred.
586 ENGINE_add() and ENGINE_remove() return 1 on success or 0 on error.
588 ENGINE_by_id() returns a valid ENGINE structure or NULL if an error
590 occurred.
591 ENGINE_init() and ENGINE_finish() return 1 on success or 0 on error.
593 All ENGINE_get_default_TYPE() functions, ENGINE_get_cipher_engine() and
595 ENGINE_get_digest_engine() return a valid ENGINE structure on success
596 or NULL if an error occurred.
597 All ENGINE_set_default_TYPE() functions return 1 on success or 0 on
599 error.
600 ENGINE_set_default() returns 1 on success or 0 on error.
602 ENGINE_get_table_flags() returns an unsigned integer value representing
604 the global table flags which are used to control the registration
605 behaviour of ENGINE implementations.
606 All ENGINE_register_TYPE() functions return 1 on success or 0 on error.
608 ENGINE_register_complete() and ENGINE_register_all_complete() always
610 return 1.
611 ENGINE_ctrl() returns a positive value on success or others on error.
613 ENGINE_cmd_is_executable() returns 1 if cmd is executable or 0
615 otherwise.
616 ENGINE_ctrl_cmd() and ENGINE_ctrl_cmd_string() return 1 on success or 0
618 on error.
619 ENGINE_new() returns a valid ENGINE structure on success or NULL if an
621 error occurred.
622 ENGINE_free() always returns 1.
624 ENGINE_up_ref() returns 1 on success or 0 on error.
626 ENGINE_set_id() and ENGINE_set_name() return 1 on success or 0 on
628 error.
629 All other ENGINE_set_* functions return 1 on success or 0 on error.
631 ENGINE_get_id() and ENGINE_get_name() return a string representing the
633 identifier and the name of the ENGINE e respectively.
634 ENGINE_get_RSA(), ENGINE_get_DSA(), ENGINE_get_DH() and
636 ENGINE_get_RAND() return corresponding method structures for each
637 algorithms.
638 ENGINE_get_destroy_function(), ENGINE_get_init_function(),
640 ENGINE_get_finish_function(), ENGINE_get_ctrl_function(),
641 ENGINE_get_load_privkey_function(), ENGINE_get_load_pubkey_function(),
642 ENGINE_get_ciphers() and ENGINE_get_digests() return corresponding
643 function pointers of the callbacks.
644 ENGINE_get_cipher() returns a valid EVP_CIPHER structure on success or
646 NULL if an error occurred.
647 ENGINE_get_digest() returns a valid EVP_MD structure on success or NULL
649 if an error occurred.
650 ENGINE_get_flags() returns an integer representing the ENGINE flags
652 which are used to control various behaviours of an ENGINE.
653 ENGINE_get_cmd_defns() returns an ENGINE_CMD_DEFN structure or NULL if
655 it's not set.
656 ENGINE_load_private_key() and ENGINE_load_public_key() return a valid
658 EVP_PKEY structure on success or NULL if an error occurred.
659
661 OPENSSL_init_crypto(3), RSA_new_method(3), DSA_new(3), DH_new(3),
662 RAND_bytes(3), config(5)
663
665 All of these functions were deprecated in OpenSSL 3.0.
666 ENGINE_cleanup() was deprecated in OpenSSL 1.1.0 by the automatic
668 cleanup done by OPENSSL_cleanup() and should not be used.
669
671 Copyright 2002-2021 The OpenSSL Project Authors. All Rights Reserved.
672 Licensed under the Apache License 2.0 (the "License"). You may not use
674 this file except in compliance with the License. You can obtain a copy
675 in the file LICENSE in the source distribution or at
676 <https://www.openssl.org/source/license.html>.
6773.1.1 2023-08-31 ENGINE_ADD(3ossl)