1 .\" $OpenBSD: crypto.9,v 1.19 2002/07/16 06:31:57 angelos Exp $
3 .\" The author of this manual page is Angelos D. Keromytis (angelos@cis.upenn.edu)
5 .\" Copyright (c) 2000, 2001 Angelos D. Keromytis
7 .\" Permission to use, copy, and modify this software with or without fee
8 .\" is hereby granted, provided that this entire notice is included in
9 .\" all source code copies of any software which is or includes a copy or
10 .\" modification of this software.
12 .\" THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
13 .\" IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
14 .\" REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
15 .\" MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
18 .\" $FreeBSD: src/share/man/man9/crypto.9,v 1.14 2007/09/19 16:28:46 brueffer Exp $
25 .Nd API for cryptographic services in the kernel
27 .In opencrypto/cryptodev.h
29 .Fn crypto_get_driverid "device_t dev" "int flags"
31 .Fn crypto_find_driver "const char *match"
33 .Fn crypto_find_device_byhid "int hid"
35 .Fn crypto_getcaps "int hid"
37 .Fn crypto_register "u_int32_t driverid" "int alg" "u_int16_t maxoplen" "u_int32_t flags"
39 .Fn crypto_kregister "u_int32_t driverid" "int kalg" "u_int32_t flags"
41 .Fn crypto_unregister "u_int32_t driverid" "int alg"
43 .Fn crypto_unregister_all "u_int32_t driverid"
45 .Fn crypto_done "struct cryptop *crp"
47 .Fn crypto_kdone "struct cryptkop *krp"
49 .Fn crypto_newsession "u_int64_t *sid" "struct cryptoini *cri" "int crid"
51 .Fn crypto_freesession "u_int64_t sid"
53 .Fn crypto_dispatch "struct cryptop *crp"
55 .Fn crypto_kdispatch "struct cryptkop *krp"
57 .Fn crypto_unblock "u_int32_t driverid" "int what"
58 .Ft "struct cryptop *"
59 .Fn crypto_getreq "int num"
61 .Fn crypto_freereq "struct cryptop *crp"
63 #define CRYPTO_SYMQ 0x1
64 #define CRYPTO_ASYMQ 0x2
66 #define EALG_MAX_BLOCK_LEN 16
73 u_int8_t cri_iv[EALG_MAX_BLOCK_LEN];
74 struct cryptoini *cri_next;
82 struct cryptoini CRD_INI;
83 #define crd_iv CRD_INI.cri_iv
84 #define crd_key CRD_INI.cri_key
85 #define crd_alg CRD_INI.cri_alg
86 #define crd_klen CRD_INI.cri_klen
87 struct cryptodesc *crd_next;
91 TAILQ_ENTRY(cryptop) crp_next;
99 struct cryptodesc *crp_desc;
100 int (*crp_callback) (struct cryptop *);
109 #define CRK_MAXPARAM 8
112 TAILQ_ENTRY(cryptkop) krp_next;
113 u_int krp_op; /* ie. CRK_MOD_EXP or other */
114 u_int krp_status; /* return status */
115 u_short krp_iparams; /* # of input parameters */
116 u_short krp_oparams; /* # of output parameters */
118 struct crparam krp_param[CRK_MAXPARAM];
119 int (*krp_callback)(struct cryptkop *);
124 is a framework for drivers of cryptographic hardware to register with
127 (other kernel subsystems, and
130 device) are able to make use of it.
131 Drivers register with the framework the algorithms they support,
132 and provide entry points (functions) the framework may call to
133 establish, use, and tear down sessions.
134 Sessions are used to cache cryptographic information in a particular driver
135 (or associated hardware), so initialization is not needed with every request.
136 Consumers of cryptographic services pass a set of
137 descriptors that instruct the framework (and the drivers registered
138 with it) of the operations that should be applied on the data (more
139 than one cryptographic operation can be requested).
141 Keying operations are supported as well.
142 Unlike the symmetric operators described above,
143 these sessionless commands perform mathematical operations using
144 input and output parameters.
146 Since the consumers may not be associated with a process, drivers may
149 The same holds for the framework.
150 Thus, a callback mechanism is used
151 to notify a consumer that a request has been completed (the
152 callback is specified by the consumer on an per-request basis).
153 The callback is invoked by the framework whether the request was
154 successfully completed or not.
155 An error indication is provided in the latter case.
156 A specific error code,
158 is used to indicate that a session number has changed and that the
159 request may be re-submitted immediately with the new session number.
160 Errors are only returned to the invoking function if not
161 enough information to call the callback is available (meaning, there
162 was a fatal error in verifying the arguments).
163 For session initialization and teardown there is no callback mechanism used.
166 .Fn crypto_newsession
167 routine is called by consumers of cryptographic services (such as the
169 stack) that wish to establish a new session with the framework.
170 On success, the first argument will contain the Session Identifier (SID).
171 The second argument contains all the necessary information for
172 the driver to establish the session.
173 The third argument indicates whether a
174 hardware driver (1) should be used or not (0).
175 The various fields in the
178 .Bl -tag -width ".Va cri_next"
180 Contains an algorithm identifier.
181 Currently supported algorithms are:
183 .Bl -tag -width ".Dv CRYPTO_RIPEMD160_HMAC" -compact
184 .It Dv CRYPTO_AES_CBC
185 .It Dv CRYPTO_AES_XTS
186 .It Dv CRYPTO_AES_CTR
188 .It Dv CRYPTO_BLF_CBC
189 .It Dv CRYPTO_CAMELLIA_CBC
190 .It Dv CRYPTO_CAST_CBC
191 .It Dv CRYPTO_DES_CBC
192 .It Dv CRYPTO_3DES_CBC
193 .It Dv CRYPTO_SKIPJACK_CBC
195 .It Dv CRYPTO_MD5_HMAC
196 .It Dv CRYPTO_MD5_KPDK
197 .It Dv CRYPTO_RIPEMD160_HMAC
199 .It Dv CRYPTO_SHA1_HMAC
200 .It Dv CRYPTO_SHA1_KPDK
201 .It Dv CRYPTO_SHA2_256_HMAC
202 .It Dv CRYPTO_SHA2_384_HMAC
203 .It Dv CRYPTO_SHA2_512_HMAC
204 .It Dv CRYPTO_NULL_HMAC
205 .It Dv CRYPTO_NULL_CBC
208 Specifies the length of the key in bits, for variable-size key
211 Specifies how many bytes from the calculated hash should be copied back.
214 Contains the key to be used with the algorithm.
216 Contains an explicit initialization vector (IV), if it does not prefix
218 This field is ignored during initialization.
219 If no IV is explicitly passed (see below on details), a random IV is used
220 by the device driver processing the request.
222 Contains a pointer to another
225 Multiple such structures may be linked to establish multi-algorithm sessions
227 is an example consumer of such a feature).
232 structure and its contents will not be modified by the framework (or
234 Subsequent requests for processing that use the
235 SID returned will avoid the cost of re-initializing the hardware (in
236 essence, SID acts as an index in the session cache of the driver).
238 .Fn crypto_freesession
239 is called with the SID returned by
240 .Fn crypto_newsession
241 to disestablish the session.
244 is called to process a request.
245 The various fields in the
248 .Bl -tag -width ".Va crp_callback"
252 Indicates the total length in bytes of the buffer to be processed.
254 On return, contains the total length of the result.
255 For symmetric crypto operations, this will be the same as the input length.
256 This will be used if the framework needs to allocate a new
257 buffer for the result (or for re-formatting the input).
259 This routine is invoked upon completion of the request, whether
261 It is invoked through the
264 If the request was not successful, an error code is set in the
267 It is the responsibility of the callback routine to enter a critical
270 Contains the error type, if any errors were encountered, or zero if
271 the request was successfully processed.
274 error code is returned, the SID has changed (and has been recorded in the
277 The consumer should record the new SID and use it in all subsequent requests.
278 In this case, the request may be re-submitted immediately.
279 This mechanism is used by the framework to perform
280 session migration (move a session from one driver to another, because
281 of availability, performance, or other considerations).
283 Note that this field only makes sense when examined by
284 the callback routine specified in
286 Errors are returned to the invoker of
288 only when enough information is not present to call the callback
289 routine (i.e., if the pointer passed is
291 or if no callback routine was specified).
293 Is a bitmask of flags associated with this request.
294 Currently defined flags are:
295 .Bl -tag -width ".Dv CRYPTO_F_CBIFSYNC"
296 .It Dv CRYPTO_F_IMBUF
297 The buffer pointed to by
301 The buffer pointed to by
307 Must return data in the same place.
308 .It Dv CRYPTO_F_BATCH
309 Batch operation if possible.
310 .It Dv CRYPTO_F_CBIMM
311 Do callback immediately instead of doing it from a dedicated kernel thread.
314 .It Dv CRYPTO_F_CBIFSYNC
315 Do callback immediately if operation is synchronous.
318 Points to the input buffer.
319 On return (when the callback is invoked),
320 it contains the result of the request.
321 The input buffer may be an mbuf
322 chain or a contiguous buffer,
326 This is passed through the crypto framework untouched and is
327 intended for the invoking application's use.
329 This is a linked list of descriptors.
330 Each descriptor provides
331 information about what type of cryptographic operation should be done
333 The various fields are:
334 .Bl -tag -width ".Va crd_inject"
336 The field where IV should be provided when the
337 .Dv CRD_F_IV_EXPLICIT
341 .Dv CRD_F_KEY_EXPLICIT
344 points to a buffer with encryption or authentication key.
347 Must be the same as the one given at newsession time.
353 The offset in the input buffer where processing should start.
355 How many bytes, after
359 Offset from the beginning of the buffer to insert any results.
360 For encryption algorithms, this is where the initialization vector
361 (IV) will be inserted when encrypting or where it can be found when
362 decrypting (subject to
364 For MAC algorithms, this is where the result of the keyed hash will be
367 The following flags are defined:
370 For encryption algorithms, this bit is set when encryption is required
371 (when not set, decryption is performed).
372 .It Dv CRD_F_IV_PRESENT
373 For encryption algorithms, this bit is set when the IV already
374 precedes the data, so the
376 value will be ignored and no IV will be written in the buffer.
377 Otherwise, the IV used to encrypt the packet will be written
378 at the location pointed to by
380 The IV length is assumed to be equal to the blocksize of the
381 encryption algorithm.
382 Some applications that do special
384 such as the half-IV mode in
386 can use this flag to indicate that the IV should not be written on the packet.
387 This flag is typically used in conjunction with the
388 .Dv CRD_F_IV_EXPLICIT
390 .It Dv CRD_F_IV_EXPLICIT
391 For encryption algorithms, this bit is set when the IV is explicitly
392 provided by the consumer in the
395 Otherwise, for encryption operations the IV is provided for by
396 the driver used to perform the operation, whereas for decryption
397 operations it is pointed to by the
400 This flag is typically used when the IV is calculated
402 by the consumer, and does not precede the data (some
404 configurations, and the encrypted swap are two such examples).
405 .It Dv CRD_F_KEY_EXPLICIT
406 For encryption and authentication (MAC) algorithms, this bit is set when the key
407 is explicitly provided by the consumer in the
409 field for the given operation.
410 Otherwise, the key is taken at newsession time from the
414 For compression algorithms, this bit is set when compression is required (when
415 not set, decompression is performed).
420 structure will not be modified by the framework or the device drivers.
421 Since this information accompanies every cryptographic
422 operation request, drivers may re-initialize state on-demand
423 (typically an expensive operation).
424 Furthermore, the cryptographic
425 framework may re-route requests as a result of full queues or hardware
426 failure, as described above.
428 Point to the next descriptor.
429 Linked operations are useful in protocols such as
431 where multiple cryptographic transforms may be applied on the same
439 structure with a linked list of as many
441 structures as were specified in the argument passed to it.
444 deallocates a structure
448 structures linked to it.
449 Note that it is the responsibility of the
450 callback routine to do the necessary cleanups associated with the
456 is called to perform a keying operation.
457 The various fields in the
460 .Bl -tag -width ".Va krp_callback"
462 Operation code, such as
468 variable indicates whether lower level reasons
469 for operation failure.
471 Number if input parameters to the specified operation.
472 Note that each operation has a (typically hardwired) number of such parameters.
474 Number if output parameters from the specified operation.
475 Note that each operation has a (typically hardwired) number of such parameters.
477 An array of kernel memory blocks containing the parameters.
479 Identifier specifying which low-level driver is being used.
481 Callback called on completion of a keying operation.
485 .Fn crypto_get_driverid ,
486 .Fn crypto_register ,
487 .Fn crypto_kregister ,
488 .Fn crypto_unregister ,
492 routines are used by drivers that provide support for cryptographic
493 primitives to register and unregister with the kernel crypto services
495 Drivers must first use the
496 .Fn crypto_get_driverid
497 function to acquire a driver identifier, specifying the
499 as an argument (normally 0, but software-only drivers should specify
500 .Dv CRYPTOCAP_F_SOFTWARE ) .
501 For each algorithm the driver supports, it must then call
502 .Fn crypto_register .
503 The first two arguments are the driver and algorithm identifiers.
504 The next two arguments specify the largest possible operator length (in bits,
505 important for public key operations) and flags for this algorithm.
506 The last four arguments must be provided in the first call to
508 and are ignored in all subsequent calls.
509 They are pointers to three
510 driver-provided functions that the framework may call to establish new
511 cryptographic context with the driver, free already established
512 context, and ask for a request to be processed (encrypt, decrypt,
513 etc.); and an opaque parameter to pass when calling each of these routines.
514 .Fn crypto_unregister
515 is called by drivers that wish to withdraw support for an algorithm.
516 The two arguments are the driver and algorithm identifiers, respectively.
517 Typically, drivers for
519 crypto cards that are being ejected will invoke this routine for all
520 algorithms supported by the card.
521 .Fn crypto_unregister_all
522 will unregister all algorithms registered by a driver
523 and the driver will be disabled (no new sessions will be allocated on
524 that driver, and any existing sessions will be migrated to other
526 The same will be done if all algorithms associated with a driver are
527 unregistered one by one.
529 The calling convention for the three driver-supplied routines is:
534 .Fn \*[lp]*newsession\*[rp] "void *" "u_int32_t *" "struct cryptoini *" ;
537 .Fn \*[lp]*freesession\*[rp] "void *" "u_int64_t" ;
540 .Fn \*[lp]*process\*[rp] "void *" "struct cryptop *" ;
543 .Fn \*[lp]*kprocess\*[rp] "void *" "struct cryptkop *" ;
546 On invocation, the first argument to
547 all routines is an opaque data value supplied when the algorithm
549 .Fn crypto_register .
550 The second argument to
552 contains the driver identifier obtained via
553 .Fn crypto_get_driverid .
554 On successful return, it should contain a driver-specific session
556 The third argument is identical to that of
557 .Fn crypto_newsession .
561 routine takes as arguments the opaque data value and the SID
562 (which is the concatenation of the
563 driver identifier and the driver-specific session identifier).
564 It should clear any context associated with the session (clear hardware
565 registers, memory, etc.).
569 routine is invoked with a request to perform crypto processing.
570 This routine must not block, but should queue the request and return
572 Upon processing the request, the callback routine should be invoked.
573 In case of an unrecoverable error, the error indication must be placed in the
578 When the request is completed, or an error is detected, the
580 routine should invoke
582 Session migration may be performed, as mentioned previously.
584 In case of a temporary resource exhaustion, the
588 in which case the crypto services will requeue the request, mark the driver
591 and stop submitting requests for processing.
592 The driver is then responsible for notifying the crypto services
593 when it is again able to process requests through the
596 This simple flow control mechanism should only be used for short-lived
597 resource exhaustion as it causes operations to be queued in the crypto
599 Doing so is preferable to returning an error in such cases as
600 it can cause network protocols to degrade performance by treating the
601 failure much like a lost packet.
605 routine is invoked with a request to perform crypto key processing.
606 This routine must not block, but should queue the request and return
608 Upon processing the request, the callback routine should be invoked.
609 In case of an unrecoverable error, the error indication must be placed in the
614 When the request is completed, or an error is detected, the
616 routine should invoked
619 .Fn crypto_register ,
620 .Fn crypto_kregister ,
621 .Fn crypto_unregister ,
622 .Fn crypto_newsession ,
623 .Fn crypto_freesession ,
626 return 0 on success, or an error code on failure.
627 .Fn crypto_get_driverid
628 returns a non-negative value on error, and \-1 on failure.
630 returns a pointer to a
638 if its argument or the callback function was
641 The callback is provided with an error code in case of failure, in the
645 .Bl -tag -width ".Pa sys/opencrypto/crypto.c"
646 .It Pa sys/opencrypto/crypto.c
647 most of the framework code
654 The cryptographic framework first appeared in
657 .An "Angelos D. Keromytis" Aq angelos@openbsd.org .
659 The framework currently assumes that all the algorithms in a
660 .Fn crypto_newsession
661 operation must be available by the same driver.
662 If that is not the case, session initialization will fail.
664 The framework also needs a mechanism for determining which driver is
665 best for a specific set of algorithms associated with a session.
666 Some type of benchmarking is in order here.
668 Multiple instances of the same algorithm in the same session are not
670 Note that 3DES is considered one algorithm (and not three
672 Thus, 3DES and DES could be mixed in the same request.