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 open the special device and
93 calls on the descriptor.
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 digests, and a second mode for
107 both asymmetric-key (public-key/private-key) requests and
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:
120 Create a new cryptography file descriptor via
122 to use for all subsequent
130 If any symmetric-keyed cryptographic or digest operations will be performed,
131 create a session with
133 Most applications will require at least one symmetric session.
134 Since cipher and MAC keys are tied to sessions, many
135 applications will require more.
136 Asymmetric operations do not use sessions.
138 Submit requests, synchronously with
147 Optionally destroy a session with
150 Close the cryptography file descriptor with
152 This will automatically close any remaining sessions associated with the
155 .Sh SYMMETRIC-KEY OPERATION
156 The symmetric-key operation mode provides a context-based API
157 to traditional symmetric-key encryption (or privacy) algorithms,
158 or to keyed and unkeyed one-way hash (HMAC and MAC) algorithms.
159 The symmetric-key mode also permits encrypt-then-authenticate fused operation,
160 where the hardware performs both a privacy algorithm and an integrity-check
161 algorithm in a single pass over the data: either a fused
162 encrypt/HMAC-generate operation, or a fused HMAC-verify/decrypt operation.
164 To use symmetric mode, you must first create a session specifying
165 the algorithm(s) and key(s) to use; then issue encrypt or decrypt
166 requests against the session.
168 For a list of supported algorithms, see
172 .Ss IOCTL Request Descriptions
174 .Bl -tag -width CIOCGSESSION
176 .It Dv CRIOGET Fa int *fd
177 Clone the fd argument to
179 yielding a new file descriptor for the creation of sessions.
181 .It Dv CIOCFINDDEV Fa struct crypt_find_op *fop
183 struct crypt_find_op {
184 int crid; /* driver id + flags */
185 char name[32]; /* device/driver name */
191 is -1, then find the driver named
197 is not -1, return the name of the driver with
201 In either case, if the driver is not found,
204 .It Dv CIOCGSESSION Fa struct session_op *sessp
207 u_int32_t cipher; /* e.g. CRYPTO_DES_CBC */
208 u_int32_t mac; /* e.g. CRYPTO_MD5_HMAC */
210 u_int32_t keylen; /* cipher key */
212 int mackeylen; /* mac key */
215 u_int32_t ses; /* returns: ses # */
219 Create a new cryptographic session on a file descriptor for the device;
220 that is, a persistent object specific to the chosen
221 privacy algorithm, integrity algorithm, and keys specified in
223 The special value 0 for either privacy or integrity
224 is reserved to indicate that the indicated operation (privacy or integrity)
225 is not desired for this session.
227 Multiple sessions may be bound to a single file descriptor.
228 The session ID returned in
230 is supplied as a required field in the symmetric-operation structure
232 for future encryption or hashing requests.
234 .\" This implementation will never return a session ID of 0 for a successful
235 .\" creation of a session, which is a
239 For non-zero symmetric-key privacy algorithms, the privacy algorithm
241 .Fa sessp-\*[Gt]cipher ,
243 .Fa sessp-\*[Gt]keylen ,
244 and the key value in the octets addressed by
245 .Fa sessp-\*[Gt]key .
247 For keyed one-way hash algorithms, the one-way hash must be specified
249 .Fa sessp-\*[Gt]mac ,
251 .Fa sessp-\*[Gt]mackey ,
252 and the key value in the octets addressed by
253 .Fa sessp-\*[Gt]mackeylen .
256 Support for a specific combination of fused privacy and
257 integrity-check algorithms depends on whether the underlying
258 hardware supports that combination.
259 Not all combinations are supported
260 by all hardware, even if the hardware supports each operation as a
261 stand-alone non-fused operation.
262 .It Dv CIOCGSESSION2 Fa struct session2_op *sessp
265 u_int32_t cipher; /* e.g. CRYPTO_DES_CBC */
266 u_int32_t mac; /* e.g. CRYPTO_MD5_HMAC */
268 u_int32_t keylen; /* cipher key */
270 int mackeylen; /* mac key */
273 u_int32_t ses; /* returns: ses # */
274 int crid; /* driver id + flags (rw) */
275 int pad[4]; /* for future expansion */
279 This request is similar to CIOGSESSION except that
281 requests either a specific crypto device or a class of devices (software vs
285 field must be initialized to zero.
286 .It Dv CIOCCRYPT Fa struct crypt_op *cr_op
290 u_int16_t op; /* e.g. COP_ENCRYPT */
294 caddr_t mac; /* must be large enough for result */
299 Request a symmetric-key (or hash) operation.
310 supplies the length of the input buffer; the fields
311 .Fa cr_op-\*[Gt]src ,
312 .Fa cr_op-\*[Gt]dst ,
313 .Fa cr_op-\*[Gt]mac ,
315 supply the addresses of the input buffer, output buffer,
316 one-way hash, and initialization vector, respectively.
318 If a session is using either fused encrypt-then-authenticate or
320 decryption operations require the associated hash as an input.
321 If the hash is incorrect, the
322 operation will fail with
324 and the output buffer will remain unchanged.
325 .It Dv CIOCCRYPTAEAD Fa struct crypt_aead *cr_aead
329 u_int16_t op; /* e.g. COP_ENCRYPT */
336 caddr_t tag; /* must be large enough for result */
345 but provides additional data in
346 .Fa cr_aead-\*[Gt]aad
347 to include in the authentication mode.
348 .It Dv CIOCFSESSION Fa u_int32_t ses_id
349 Destroys the session identified by
353 .Sh ASYMMETRIC-KEY OPERATION
354 .Ss Asymmetric-key algorithms
355 Contingent upon hardware support, the following asymmetric
356 (public-key/private-key; or key-exchange subroutine) operations may
359 .Bl -column "CRK_DH_COMPUTE_KEY" "Input parameter" "Output parameter" -offset indent -compact
360 .It Em "Algorithm" Ta "Input parameter" Ta "Output parameter"
361 .It Em " " Ta "Count" Ta "Count"
362 .It Dv CRK_MOD_EXP Ta 3 Ta 1
363 .It Dv CRK_MOD_EXP_CRT Ta 6 Ta 1
364 .It Dv CRK_DSA_SIGN Ta 5 Ta 2
365 .It Dv CRK_DSA_VERIFY Ta 7 Ta 0
366 .It Dv CRK_DH_COMPUTE_KEY Ta 3 Ta 1
369 See below for discussion of the input and output parameter counts.
370 .Ss Asymmetric-key commands
371 .Bl -tag -width CIOCKEY
372 .It Dv CIOCASYMFEAT Fa int *feature_mask
373 Returns a bitmask of supported asymmetric-key operations.
374 Each of the above-listed asymmetric operations is present
375 if and only if the bit position numbered by the code for that operation
379 is available if and only if the bit
380 .Pq 1 \*[Lt]\*[Lt] Dv CRK_MOD_EXP
382 .It Dv CIOCKEY Fa struct crypt_kop *kop
385 u_int crk_op; /* e.g. CRK_MOD_EXP */
386 u_int crk_status; /* return status */
387 u_short crk_iparams; /* # of input params */
388 u_short crk_oparams; /* # of output params */
390 struct crparam crk_param[CRK_MAXPARAM];
393 /* Bignum parameter, in packed bytes. */
400 Performs an asymmetric-key operation from the list above.
401 The specific operation is supplied in
402 .Fa kop-\*[Gt]crk_op ;
403 final status for the operation is returned in
404 .Fa kop-\*[Gt]crk_status .
405 The number of input arguments and the number of output arguments
407 .Fa kop-\*[Gt]crk_iparams
409 .Fa kop-\*[Gt]crk_iparams ,
413 must be filled in with exactly
414 .Fa kop-\*[Gt]crk_iparams + kop-\*[Gt]crk_oparams
415 arguments, each encoded as a
417 (address, bitlength) pair.
419 The semantics of these arguments are currently undocumented.
433 driver first appeared in
437 driver was imported to
440 Error checking and reporting is weak.
442 The values specified for symmetric-key key sizes to
444 must exactly match the values expected by
446 The output buffer and MAC buffers supplied to
448 must follow whether privacy or integrity algorithms were specified for
449 session: if you request a
451 algorithm, you must supply a suitably-sized buffer.
453 The scheme for passing arguments for asymmetric requests is baroque.
457 It should be possible to use the
459 commands directly on a