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 .
105 device provides two distinct modes of operation: one mode for
106 symmetric-keyed cryptographic requests, and a second mode for
107 both asymmetric-key (public-key/private-key) requests, and for
108 modular arithmetic (for Diffie-Hellman key exchange and other
109 cryptographic protocols).
110 The two modes are described separately below.
111 .Sh THEORY OF OPERATION
112 Regardless of whether symmetric-key or asymmetric-key operations are
113 to be performed, use of the device requires a basic series of steps:
116 Open a file descriptor for the device.
120 If any symmetric operation will be performed,
121 create one session, with
123 Most applications will require at least one symmetric session.
124 Since cipher and MAC keys are tied to sessions, many
125 applications will require more.
126 Asymmetric operations do not use sessions.
128 Submit requests, synchronously with
135 Destroy one session with
138 Close the device with
141 .Sh SYMMETRIC-KEY OPERATION
142 The symmetric-key operation mode provides a context-based API
143 to traditional symmetric-key encryption (or privacy) algorithms,
144 or to keyed and unkeyed one-way hash (HMAC and MAC) algorithms.
145 The symmetric-key mode also permits fused operation,
146 where the hardware performs both a privacy algorithm and an integrity-check
147 algorithm in a single pass over the data: either a fused
148 encrypt/HMAC-generate operation, or a fused HMAC-verify/decrypt operation.
150 To use symmetric mode, you must first create a session specifying
151 the algorithm(s) and key(s) to use; then issue encrypt or decrypt
152 requests against the session.
154 For a list of supported algorithms, see
158 .Ss IOCTL Request Descriptions
160 .Bl -tag -width CIOCGSESSION
162 .It Dv CRIOGET Fa int *fd
163 Clone the fd argument to
165 yielding a new file descriptor for the creation of sessions.
167 .It Dv CIOCFINDDEV Fa struct crypt_find_op *fop
169 struct crypt_find_op {
170 int crid; /* driver id + flags */
171 char name[32]; /* device/driver name */
177 is -1, then find the driver named
183 is not -1, return the name of the driver with
187 In either case, if the driver is not found,
190 .It Dv CIOCGSESSION Fa struct session_op *sessp
193 u_int32_t cipher; /* e.g. CRYPTO_DES_CBC */
194 u_int32_t mac; /* e.g. CRYPTO_MD5_HMAC */
196 u_int32_t keylen; /* cipher key */
198 int mackeylen; /* mac key */
201 u_int32_t ses; /* returns: ses # */
205 Create a new cryptographic session on a file descriptor for the device;
206 that is, a persistent object specific to the chosen
207 privacy algorithm, integrity algorithm, and keys specified in
209 The special value 0 for either privacy or integrity
210 is reserved to indicate that the indicated operation (privacy or integrity)
211 is not desired for this session.
213 Multiple sessions may be bound to a single file descriptor.
214 The session ID returned in
216 is supplied as a required field in the symmetric-operation structure
218 for future encryption or hashing requests.
220 .\" This implementation will never return a session ID of 0 for a successful
221 .\" creation of a session, which is a
225 For non-zero symmetric-key privacy algorithms, the privacy algorithm
227 .Fa sessp-\*[Gt]cipher ,
229 .Fa sessp-\*[Gt]keylen ,
230 and the key value in the octets addressed by
231 .Fa sessp-\*[Gt]key .
233 For keyed one-way hash algorithms, the one-way hash must be specified
235 .Fa sessp-\*[Gt]mac ,
237 .Fa sessp-\*[Gt]mackey ,
238 and the key value in the octets addressed by
239 .Fa sessp-\*[Gt]mackeylen .
242 Support for a specific combination of fused privacy and
243 integrity-check algorithms depends on whether the underlying
244 hardware supports that combination.
245 Not all combinations are supported
246 by all hardware, even if the hardware supports each operation as a
247 stand-alone non-fused operation.
248 .It Dv CIOCCRYPT Fa struct crypt_op *cr_op
252 u_int16_t op; /* e.g. COP_ENCRYPT */
256 caddr_t mac; /* must be large enough for result */
261 Request a symmetric-key (or hash) operation.
262 The file descriptor argument to
264 must have been bound to a valid session.
275 supplies the length of the input buffer; the fields
276 .Fa cr_op-\*[Gt]src ,
277 .Fa cr_op-\*[Gt]dst ,
278 .Fa cr_op-\*[Gt]mac ,
280 supply the addresses of the input buffer, output buffer,
281 one-way hash, and initialization vector, respectively.
282 .It Dv CIOCCRYPTAEAD Fa struct crypt_aead *cr_aead
286 u_int16_t op; /* e.g. COP_ENCRYPT */
293 caddr_t tag; /* must be large enough for result */
302 but provides additional data in
303 .Fa cr_aead-\*[Gt]aad
304 to include in the authentication mode.
305 .It Dv CIOCFSESSION Fa u_int32_t ses_id
306 Destroys the /dev/crypto session associated with the file-descriptor
308 .It Dv CIOCNFSESSION Fa struct crypt_sfop *sfop ;
318 sessions specified by the
320 array of session identifiers.
323 .Sh ASYMMETRIC-KEY OPERATION
324 .Ss Asymmetric-key algorithms
325 Contingent upon hardware support, the following asymmetric
326 (public-key/private-key; or key-exchange subroutine) operations may
329 .Bl -column "CRK_DH_COMPUTE_KEY" "Input parameter" "Output parameter" -offset indent -compact
330 .It Em "Algorithm" Ta "Input parameter" Ta "Output parameter"
331 .It Em " " Ta "Count" Ta "Count"
332 .It Dv CRK_MOD_EXP Ta 3 Ta 1
333 .It Dv CRK_MOD_EXP_CRT Ta 6 Ta 1
334 .It Dv CRK_DSA_SIGN Ta 5 Ta 2
335 .It Dv CRK_DSA_VERIFY Ta 7 Ta 0
336 .It Dv CRK_DH_COMPUTE_KEY Ta 3 Ta 1
339 See below for discussion of the input and output parameter counts.
340 .Ss Asymmetric-key commands
341 .Bl -tag -width CIOCKEY
342 .It Dv CIOCASYMFEAT Fa int *feature_mask
343 Returns a bitmask of supported asymmetric-key operations.
344 Each of the above-listed asymmetric operations is present
345 if and only if the bit position numbered by the code for that operation
349 is available if and only if the bit
350 .Pq 1 \*[Lt]\*[Lt] Dv CRK_MOD_EXP
352 .It Dv CIOCKEY Fa struct crypt_kop *kop
355 u_int crk_op; /* e.g. CRK_MOD_EXP */
356 u_int crk_status; /* return status */
357 u_short crk_iparams; /* # of input params */
358 u_short crk_oparams; /* # of output params */
360 struct crparam crk_param[CRK_MAXPARAM];
363 /* Bignum parameter, in packed bytes. */
370 Performs an asymmetric-key operation from the list above.
371 The specific operation is supplied in
372 .Fa kop-\*[Gt]crk_op ;
373 final status for the operation is returned in
374 .Fa kop-\*[Gt]crk_status .
375 The number of input arguments and the number of output arguments
377 .Fa kop-\*[Gt]crk_iparams
379 .Fa kop-\*[Gt]crk_iparams ,
383 must be filled in with exactly
384 .Fa kop-\*[Gt]crk_iparams + kop-\*[Gt]crk_oparams
385 arguments, each encoded as a
387 (address, bitlength) pair.
389 The semantics of these arguments are currently undocumented.
404 driver first appeared in
408 driver was imported to
411 Error checking and reporting is weak.
413 The values specified for symmetric-key key sizes to
415 must exactly match the values expected by
417 The output buffer and MAC buffers supplied to
419 must follow whether privacy or integrity algorithms were specified for
420 session: if you request a
422 algorithm, you must supply a suitably-sized buffer.
424 The scheme for passing arguments for asymmetric requests is baroque.
426 The naming inconsistency between
430 names is an unfortunate historical artifact.