1 .\" $NetBSD: crypto.4,v 1.24 2014/01/27 21:23:59 pgoyette Exp $
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38 .\" Jonathan Stone <jonathan@dsg.stanford.edu>. All rights reserved.
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69 .Nd user-mode access to hardware-accelerated cryptography
76 .In crypto/cryptodev.h
80 driver gives user-mode applications access to hardware-accelerated
81 cryptographic transforms, as implemented by the
87 special device provides an
90 User-mode applications should open the special device,
93 calls on the descriptor.
96 is controlled by three
99 .Ic kern.userasymcrypto
101 .Ic kern.cryptodevallowsoft .
104 for additional details.
108 device provides two distinct modes of operation: one mode for
109 symmetric-keyed cryptographic requests, and a second mode for
110 both asymmetric-key (public-key/private-key) requests, and for
111 modular arithmetic (for Diffie-Hellman key exchange and other
112 cryptographic protocols).
113 The two modes are described separately below.
114 .Sh THEORY OF OPERATION
115 Regardless of whether symmetric-key or asymmetric-key operations are
116 to be performed, use of the device requires a basic series of steps:
119 Open a file descriptor for the device.
123 If any symmetric operation will be performed,
124 create one session, with
126 Most applications will require at least one symmetric session.
127 Since cipher and MAC keys are tied to sessions, many
128 applications will require more.
129 Asymmetric operations do not use sessions.
131 Submit requests, synchronously with
138 Destroy one session with
141 Close the device with
144 .Sh SYMMETRIC-KEY OPERATION
145 The symmetric-key operation mode provides a context-based API
146 to traditional symmetric-key encryption (or privacy) algorithms,
147 or to keyed and unkeyed one-way hash (HMAC and MAC) algorithms.
148 The symmetric-key mode also permits fused operation,
149 where the hardware performs both a privacy algorithm and an integrity-check
150 algorithm in a single pass over the data: either a fused
151 encrypt/HMAC-generate operation, or a fused HMAC-verify/decrypt operation.
153 To use symmetric mode, you must first create a session specifying
154 the algorithm(s) and key(s) to use; then issue encrypt or decrypt
155 requests against the session.
157 For a list of supported algorithms, see
161 .Ss IOCTL Request Descriptions
163 .Bl -tag -width CIOCGSESSION
165 .It Dv CRIOGET Fa int *fd
166 Clone the fd argument to
168 yielding a new file descriptor for the creation of sessions.
170 .It Dv CIOCFINDDEV Fa struct crypt_find_op *fop
172 struct crypt_find_op {
173 int crid; /* driver id + flags */
174 char name[32]; /* device/driver name */
180 is -1, then find the driver named
186 is not -1, return the name of the driver with
190 In either case, if the driver is not found,
193 .It Dv CIOCGSESSION Fa struct session_op *sessp
196 u_int32_t cipher; /* e.g. CRYPTO_DES_CBC */
197 u_int32_t mac; /* e.g. CRYPTO_MD5_HMAC */
199 u_int32_t keylen; /* cipher key */
201 int mackeylen; /* mac key */
204 u_int32_t ses; /* returns: ses # */
208 Create a new cryptographic session on a file descriptor for the device;
209 that is, a persistent object specific to the chosen
210 privacy algorithm, integrity algorithm, and keys specified in
212 The special value 0 for either privacy or integrity
213 is reserved to indicate that the indicated operation (privacy or integrity)
214 is not desired for this session.
216 Multiple sessions may be bound to a single file descriptor.
217 The session ID returned in
219 is supplied as a required field in the symmetric-operation structure
221 for future encryption or hashing requests.
223 .\" This implementation will never return a session ID of 0 for a successful
224 .\" creation of a session, which is a
228 For non-zero symmetric-key privacy algorithms, the privacy algorithm
230 .Fa sessp-\*[Gt]cipher ,
232 .Fa sessp-\*[Gt]keylen ,
233 and the key value in the octets addressed by
234 .Fa sessp-\*[Gt]key .
236 For keyed one-way hash algorithms, the one-way hash must be specified
238 .Fa sessp-\*[Gt]mac ,
240 .Fa sessp-\*[Gt]mackey ,
241 and the key value in the octets addressed by
242 .Fa sessp-\*[Gt]mackeylen .
245 Support for a specific combination of fused privacy and
246 integrity-check algorithms depends on whether the underlying
247 hardware supports that combination.
248 Not all combinations are supported
249 by all hardware, even if the hardware supports each operation as a
250 stand-alone non-fused operation.
251 .It Dv CIOCCRYPT Fa struct crypt_op *cr_op
255 u_int16_t op; /* e.g. COP_ENCRYPT */
259 caddr_t mac; /* must be large enough for result */
264 Request a symmetric-key (or hash) operation.
265 The file descriptor argument to
267 must have been bound to a valid session.
278 supplies the length of the input buffer; the fields
279 .Fa cr_op-\*[Gt]src ,
280 .Fa cr_op-\*[Gt]dst ,
281 .Fa cr_op-\*[Gt]mac ,
283 supply the addresses of the input buffer, output buffer,
284 one-way hash, and initialization vector, respectively.
285 .It Dv CIOCCRYPTAEAD Fa struct crypt_aead *cr_aead
289 u_int16_t op; /* e.g. COP_ENCRYPT */
296 caddr_t tag; /* must be large enough for result */
305 but provides additional data in
306 .Fa cr_aead-\*[Gt]aad
307 to include in the authentication mode.
308 .It Dv CIOCFSESSION Fa u_int32_t ses_id
309 Destroys the /dev/crypto session associated with the file-descriptor
311 .It Dv CIOCNFSESSION Fa struct crypt_sfop *sfop ;
321 sessions specified by the
323 array of session identifiers.
326 .Sh ASYMMETRIC-KEY OPERATION
327 .Ss Asymmetric-key algorithms
328 Contingent upon hardware support, the following asymmetric
329 (public-key/private-key; or key-exchange subroutine) operations may
332 .Bl -column "CRK_DH_COMPUTE_KEY" "Input parameter" "Output parameter" -offset indent -compact
333 .It Em "Algorithm" Ta "Input parameter" Ta "Output parameter"
334 .It Em " " Ta "Count" Ta "Count"
335 .It Dv CRK_MOD_EXP Ta 3 Ta 1
336 .It Dv CRK_MOD_EXP_CRT Ta 6 Ta 1
337 .It Dv CRK_DSA_SIGN Ta 5 Ta 2
338 .It Dv CRK_DSA_VERIFY Ta 7 Ta 0
339 .It Dv CRK_DH_COMPUTE_KEY Ta 3 Ta 1
342 See below for discussion of the input and output parameter counts.
343 .Ss Asymmetric-key commands
344 .Bl -tag -width CIOCKEY
345 .It Dv CIOCASYMFEAT Fa int *feature_mask
346 Returns a bitmask of supported asymmetric-key operations.
347 Each of the above-listed asymmetric operations is present
348 if and only if the bit position numbered by the code for that operation
352 is available if and only if the bit
353 .Pq 1 \*[Lt]\*[Lt] Dv CRK_MOD_EXP
355 .It Dv CIOCKEY Fa struct crypt_kop *kop
358 u_int crk_op; /* e.g. CRK_MOD_EXP */
359 u_int crk_status; /* return status */
360 u_short crk_iparams; /* # of input params */
361 u_short crk_oparams; /* # of output params */
363 struct crparam crk_param[CRK_MAXPARAM];
366 /* Bignum parameter, in packed bytes. */
373 Performs an asymmetric-key operation from the list above.
374 The specific operation is supplied in
375 .Fa kop-\*[Gt]crk_op ;
376 final status for the operation is returned in
377 .Fa kop-\*[Gt]crk_status .
378 The number of input arguments and the number of output arguments
380 .Fa kop-\*[Gt]crk_iparams
382 .Fa kop-\*[Gt]crk_iparams ,
386 must be filled in with exactly
387 .Fa kop-\*[Gt]crk_iparams + kop-\*[Gt]crk_oparams
388 arguments, each encoded as a
390 (address, bitlength) pair.
392 The semantics of these arguments are currently undocumented.
407 driver first appeared in
411 driver was imported to
414 Error checking and reporting is weak.
416 The values specified for symmetric-key key sizes to
418 must exactly match the values expected by
420 The output buffer and MAC buffers supplied to
422 must follow whether privacy or integrity algorithms were specified for
423 session: if you request a
425 algorithm, you must supply a suitably-sized buffer.
427 The scheme for passing arguments for asymmetric requests is baroque.
429 The naming inconsistency between
433 names is an unfortunate historical artifact.