summaryrefslogtreecommitdiffstats
path: root/tools/testing/selftests/tpm2/tpm2.py
blob: 3e67fdb518ec32f31e4a49a5dde70902ace20fe3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
# SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)

import hashlib
import os
import socket
import struct
import sys
import unittest
import fcntl
import select

TPM2_ST_NO_SESSIONS = 0x8001
TPM2_ST_SESSIONS = 0x8002

TPM2_CC_FIRST = 0x01FF

TPM2_CC_CREATE_PRIMARY = 0x0131
TPM2_CC_DICTIONARY_ATTACK_LOCK_RESET = 0x0139
TPM2_CC_CREATE = 0x0153
TPM2_CC_LOAD = 0x0157
TPM2_CC_UNSEAL = 0x015E
TPM2_CC_FLUSH_CONTEXT = 0x0165
TPM2_CC_START_AUTH_SESSION = 0x0176
TPM2_CC_GET_CAPABILITY	= 0x017A
TPM2_CC_GET_RANDOM = 0x017B
TPM2_CC_PCR_READ = 0x017E
TPM2_CC_POLICY_PCR = 0x017F
TPM2_CC_PCR_EXTEND = 0x0182
TPM2_CC_POLICY_PASSWORD = 0x018C
TPM2_CC_POLICY_GET_DIGEST = 0x0189

TPM2_SE_POLICY = 0x01
TPM2_SE_TRIAL = 0x03

TPM2_ALG_RSA = 0x0001
TPM2_ALG_SHA1 = 0x0004
TPM2_ALG_AES = 0x0006
TPM2_ALG_KEYEDHASH = 0x0008
TPM2_ALG_SHA256 = 0x000B
TPM2_ALG_NULL = 0x0010
TPM2_ALG_CBC = 0x0042
TPM2_ALG_CFB = 0x0043

TPM2_RH_OWNER = 0x40000001
TPM2_RH_NULL = 0x40000007
TPM2_RH_LOCKOUT = 0x4000000A
TPM2_RS_PW = 0x40000009

TPM2_RC_SIZE            = 0x01D5
TPM2_RC_AUTH_FAIL       = 0x098E
TPM2_RC_POLICY_FAIL     = 0x099D
TPM2_RC_COMMAND_CODE    = 0x0143

TSS2_RC_LAYER_SHIFT = 16
TSS2_RESMGR_TPM_RC_LAYER = (11 << TSS2_RC_LAYER_SHIFT)

TPM2_CAP_HANDLES = 0x00000001
TPM2_CAP_COMMANDS = 0x00000002
TPM2_CAP_TPM_PROPERTIES = 0x00000006

TPM2_PT_FIXED = 0x100
TPM2_PT_TOTAL_COMMANDS = TPM2_PT_FIXED + 41

HR_SHIFT = 24
HR_LOADED_SESSION = 0x02000000
HR_TRANSIENT = 0x80000000

SHA1_DIGEST_SIZE = 20
SHA256_DIGEST_SIZE = 32

TPM2_VER0_ERRORS = {
    0x000: "TPM_RC_SUCCESS",
    0x030: "TPM_RC_BAD_TAG",
}

TPM2_VER1_ERRORS = {
    0x000: "TPM_RC_FAILURE",
    0x001: "TPM_RC_FAILURE",
    0x003: "TPM_RC_SEQUENCE",
    0x00B: "TPM_RC_PRIVATE",
    0x019: "TPM_RC_HMAC",
    0x020: "TPM_RC_DISABLED",
    0x021: "TPM_RC_EXCLUSIVE",
    0x024: "TPM_RC_AUTH_TYPE",
    0x025: "TPM_RC_AUTH_MISSING",
    0x026: "TPM_RC_POLICY",
    0x027: "TPM_RC_PCR",
    0x028: "TPM_RC_PCR_CHANGED",
    0x02D: "TPM_RC_UPGRADE",
    0x02E: "TPM_RC_TOO_MANY_CONTEXTS",
    0x02F: "TPM_RC_AUTH_UNAVAILABLE",
    0x030: "TPM_RC_REBOOT",
    0x031: "TPM_RC_UNBALANCED",
    0x042: "TPM_RC_COMMAND_SIZE",
    0x043: "TPM_RC_COMMAND_CODE",
    0x044: "TPM_RC_AUTHSIZE",
    0x045: "TPM_RC_AUTH_CONTEXT",
    0x046: "TPM_RC_NV_RANGE",
    0x047: "TPM_RC_NV_SIZE",
    0x048: "TPM_RC_NV_LOCKED",
    0x049: "TPM_RC_NV_AUTHORIZATION",
    0x04A: "TPM_RC_NV_UNINITIALIZED",
    0x04B: "TPM_RC_NV_SPACE",
    0x04C: "TPM_RC_NV_DEFINED",
    0x050: "TPM_RC_BAD_CONTEXT",
    0x051: "TPM_RC_CPHASH",
    0x052: "TPM_RC_PARENT",
    0x053: "TPM_RC_NEEDS_TEST",
    0x054: "TPM_RC_NO_RESULT",
    0x055: "TPM_RC_SENSITIVE",
    0x07F: "RC_MAX_FM0",
}

TPM2_FMT1_ERRORS = {
    0x001: "TPM_RC_ASYMMETRIC",
    0x002: "TPM_RC_ATTRIBUTES",
    0x003: "TPM_RC_HASH",
    0x004: "TPM_RC_VALUE",
    0x005: "TPM_RC_HIERARCHY",
    0x007: "TPM_RC_KEY_SIZE",
    0x008: "TPM_RC_MGF",
    0x009: "TPM_RC_MODE",
    0x00A: "TPM_RC_TYPE",
    0x00B: "TPM_RC_HANDLE",
    0x00C: "TPM_RC_KDF",
    0x00D: "TPM_RC_RANGE",
    0x00E: "TPM_RC_AUTH_FAIL",
    0x00F: "TPM_RC_NONCE",
    0x010: "TPM_RC_PP",
    0x012: "TPM_RC_SCHEME",
    0x015: "TPM_RC_SIZE",
    0x016: "TPM_RC_SYMMETRIC",
    0x017: "TPM_RC_TAG",
    0x018: "TPM_RC_SELECTOR",
    0x01A: "TPM_RC_INSUFFICIENT",
    0x01B: "TPM_RC_SIGNATURE",
    0x01C: "TPM_RC_KEY",
    0x01D: "TPM_RC_POLICY_FAIL",
    0x01F: "TPM_RC_INTEGRITY",
    0x020: "TPM_RC_TICKET",
    0x021: "TPM_RC_RESERVED_BITS",
    0x022: "TPM_RC_BAD_AUTH",
    0x023: "TPM_RC_EXPIRED",
    0x024: "TPM_RC_POLICY_CC",
    0x025: "TPM_RC_BINDING",
    0x026: "TPM_RC_CURVE",
    0x027: "TPM_RC_ECC_POINT",
}

TPM2_WARN_ERRORS = {
    0x001: "TPM_RC_CONTEXT_GAP",
    0x002: "TPM_RC_OBJECT_MEMORY",
    0x003: "TPM_RC_SESSION_MEMORY",
    0x004: "TPM_RC_MEMORY",
    0x005: "TPM_RC_SESSION_HANDLES",
    0x006: "TPM_RC_OBJECT_HANDLES",
    0x007: "TPM_RC_LOCALITY",
    0x008: "TPM_RC_YIELDED",
    0x009: "TPM_RC_CANCELED",
    0x00A: "TPM_RC_TESTING",
    0x010: "TPM_RC_REFERENCE_H0",
    0x011: "TPM_RC_REFERENCE_H1",
    0x012: "TPM_RC_REFERENCE_H2",
    0x013: "TPM_RC_REFERENCE_H3",
    0x014: "TPM_RC_REFERENCE_H4",
    0x015: "TPM_RC_REFERENCE_H5",
    0x016: "TPM_RC_REFERENCE_H6",
    0x018: "TPM_RC_REFERENCE_S0",
    0x019: "TPM_RC_REFERENCE_S1",
    0x01A: "TPM_RC_REFERENCE_S2",
    0x01B: "TPM_RC_REFERENCE_S3",
    0x01C: "TPM_RC_REFERENCE_S4",
    0x01D: "TPM_RC_REFERENCE_S5",
    0x01E: "TPM_RC_REFERENCE_S6",
    0x020: "TPM_RC_NV_RATE",
    0x021: "TPM_RC_LOCKOUT",
    0x022: "TPM_RC_RETRY",
    0x023: "TPM_RC_NV_UNAVAILABLE",
    0x7F: "TPM_RC_NOT_USED",
}

RC_VER1 = 0x100
RC_FMT1 = 0x080
RC_WARN = 0x900

ALG_DIGEST_SIZE_MAP = {
    TPM2_ALG_SHA1: SHA1_DIGEST_SIZE,
    TPM2_ALG_SHA256: SHA256_DIGEST_SIZE,
}

ALG_HASH_FUNCTION_MAP = {
    TPM2_ALG_SHA1: hashlib.sha1,
    TPM2_ALG_SHA256: hashlib.sha256
}

NAME_ALG_MAP = {
    "sha1": TPM2_ALG_SHA1,
    "sha256": TPM2_ALG_SHA256,
}


class UnknownAlgorithmIdError(Exception):
    def __init__(self, alg):
        self.alg = alg

    def __str__(self):
        return '0x%0x' % (alg)


class UnknownAlgorithmNameError(Exception):
    def __init__(self, name):
        self.name = name

    def __str__(self):
        return name


class UnknownPCRBankError(Exception):
    def __init__(self, alg):
        self.alg = alg

    def __str__(self):
        return '0x%0x' % (alg)


class ProtocolError(Exception):
    def __init__(self, cc, rc):
        self.cc = cc
        self.rc = rc

        if (rc & RC_FMT1) == RC_FMT1:
            self.name = TPM2_FMT1_ERRORS.get(rc & 0x3f, "TPM_RC_UNKNOWN")
        elif (rc & RC_WARN) == RC_WARN:
            self.name = TPM2_WARN_ERRORS.get(rc & 0x7f, "TPM_RC_UNKNOWN")
        elif (rc & RC_VER1) == RC_VER1:
            self.name = TPM2_VER1_ERRORS.get(rc & 0x7f, "TPM_RC_UNKNOWN")
        else:
            self.name = TPM2_VER0_ERRORS.get(rc & 0x7f, "TPM_RC_UNKNOWN")

    def __str__(self):
        if self.cc:
            return '%s: cc=0x%08x, rc=0x%08x' % (self.name, self.cc, self.rc)
        else:
            return '%s: rc=0x%08x' % (self.name, self.rc)


class AuthCommand(object):
    """TPMS_AUTH_COMMAND"""

    def __init__(self, session_handle=TPM2_RS_PW, nonce=bytes(),
                 session_attributes=0, hmac=bytes()):
        self.session_handle = session_handle
        self.nonce = nonce
        self.session_attributes = session_attributes
        self.hmac = hmac

    def __bytes__(self):
        fmt = '>I H%us B H%us' % (len(self.nonce), len(self.hmac))
        return struct.pack(fmt, self.session_handle, len(self.nonce),
                           self.nonce, self.session_attributes, len(self.hmac),
                           self.hmac)

    def __len__(self):
        fmt = '>I H%us B H%us' % (len(self.nonce), len(self.hmac))
        return struct.calcsize(fmt)


class SensitiveCreate(object):
    """TPMS_SENSITIVE_CREATE"""

    def __init__(self, user_auth=bytes(), data=bytes()):
        self.user_auth = user_auth
        self.data = data

    def __bytes__(self):
        fmt = '>H%us H%us' % (len(self.user_auth), len(self.data))
        return struct.pack(fmt, len(self.user_auth), self.user_auth,
                           len(self.data), self.data)

    def __len__(self):
        fmt = '>H%us H%us' % (len(self.user_auth), len(self.data))
        return struct.calcsize(fmt)


class Public(object):
    """TPMT_PUBLIC"""

    FIXED_TPM = (1 << 1)
    FIXED_PARENT = (1 << 4)
    SENSITIVE_DATA_ORIGIN = (1 << 5)
    USER_WITH_AUTH = (1 << 6)
    RESTRICTED = (1 << 16)
    DECRYPT = (1 << 17)

    def __fmt(self):
        return '>HHIH%us%usH%us' % \
            (len(self.auth_policy), len(self.parameters), len(self.unique))

    def __init__(self, object_type, name_alg, object_attributes,
                 auth_policy=bytes(), parameters=bytes(),
                 unique=bytes()):
        self.object_type = object_type
        self.name_alg = name_alg
        self.object_attributes = object_attributes
        self.auth_policy = auth_policy
        self.parameters = parameters
        self.unique = unique

    def __bytes__(self):
        return struct.pack(self.__fmt(),
                           self.object_type,
                           self.name_alg,
                           self.object_attributes,
                           len(self.auth_policy),
                           self.auth_policy,
                           self.parameters,
                           len(self.unique),
                           self.unique)

    def __len__(self):
        return struct.calcsize(self.__fmt())


def get_digest_size(alg):
    ds = ALG_DIGEST_SIZE_MAP.get(alg)
    if not ds:
        raise UnknownAlgorithmIdError(alg)
    return ds


def get_hash_function(alg):
    f = ALG_HASH_FUNCTION_MAP.get(alg)
    if not f:
        raise UnknownAlgorithmIdError(alg)
    return f


def get_algorithm(name):
    alg = NAME_ALG_MAP.get(name)
    if not alg:
        raise UnknownAlgorithmNameError(name)
    return alg


def hex_dump(d):
    d = [format(ord(x), '02x') for x in d]
    d = [d[i: i + 16] for i in range(0, len(d), 16)]
    d = [' '.join(x) for x in d]
    d = os.linesep.join(d)

    return d

class Client:
    FLAG_DEBUG = 0x01
    FLAG_SPACE = 0x02
    FLAG_NONBLOCK = 0x04
    TPM_IOC_NEW_SPACE = 0xa200

    def __init__(self, flags = 0):
        self.flags = flags

        if (self.flags & Client.FLAG_SPACE) == 0:
            self.tpm = open('/dev/tpm0', 'r+b', buffering=0)
        else:
            self.tpm = open('/dev/tpmrm0', 'r+b', buffering=0)

        if (self.flags & Client.FLAG_NONBLOCK):
            flags = fcntl.fcntl(self.tpm, fcntl.F_GETFL)
            flags |= os.O_NONBLOCK
            fcntl.fcntl(self.tpm, fcntl.F_SETFL, flags)
            self.tpm_poll = select.poll()

    def __del__(self):
        if self.tpm:
            self.tpm.close()

    def close(self):
        self.tpm.close()

    def send_cmd(self, cmd):
        self.tpm.write(cmd)

        if (self.flags & Client.FLAG_NONBLOCK):
            self.tpm_poll.register(self.tpm, select.POLLIN)
            self.tpm_poll.poll(10000)

        rsp = self.tpm.read()

        if (self.flags & Client.FLAG_NONBLOCK):
            self.tpm_poll.unregister(self.tpm)

        if (self.flags & Client.FLAG_DEBUG) != 0:
            sys.stderr.write('cmd' + os.linesep)
            sys.stderr.write(hex_dump(cmd) + os.linesep)
            sys.stderr.write('rsp' + os.linesep)
            sys.stderr.write(hex_dump(rsp) + os.linesep)

        rc = struct.unpack('>I', rsp[6:10])[0]
        if rc != 0:
            cc = struct.unpack('>I', cmd[6:10])[0]
            raise ProtocolError(cc, rc)

        return rsp

    def read_pcr(self, i, bank_alg = TPM2_ALG_SHA1):
        pcrsel_len = max((i >> 3) + 1, 3)
        pcrsel = [0] * pcrsel_len
        pcrsel[i >> 3] = 1 << (i & 7)
        pcrsel = ''.join(map(chr, pcrsel)).encode()

        fmt = '>HII IHB%us' % (pcrsel_len)
        cmd = struct.pack(fmt,
                          TPM2_ST_NO_SESSIONS,
                          struct.calcsize(fmt),
                          TPM2_CC_PCR_READ,
                          1,
                          bank_alg,
                          pcrsel_len, pcrsel)

        rsp = self.send_cmd(cmd)

        pcr_update_cnt, pcr_select_cnt = struct.unpack('>II', rsp[10:18])
        assert pcr_select_cnt == 1
        rsp = rsp[18:]

        alg2, pcrsel_len2 = struct.unpack('>HB', rsp[:3])
        assert bank_alg == alg2 and pcrsel_len == pcrsel_len2
        rsp = rsp[3 + pcrsel_len:]

        digest_cnt = struct.unpack('>I', rsp[:4])[0]
        if digest_cnt == 0:
            return None
        rsp = rsp[6:]

        return rsp

    def extend_pcr(self, i, dig, bank_alg = TPM2_ALG_SHA1):
        ds = get_digest_size(bank_alg)
        assert(ds == len(dig))

        auth_cmd = AuthCommand()

        fmt = '>HII I I%us IH%us' % (len(auth_cmd), ds)
        cmd = struct.pack(
            fmt,
            TPM2_ST_SESSIONS,
            struct.calcsize(fmt),
            TPM2_CC_PCR_EXTEND,
            i,
            len(auth_cmd),
            bytes(auth_cmd),
            1, bank_alg, dig)

        self.send_cmd(cmd)

    def start_auth_session(self, session_type, name_alg = TPM2_ALG_SHA1):
        fmt = '>HII IIH16sHBHH'
        cmd = struct.pack(fmt,
                          TPM2_ST_NO_SESSIONS,
                          struct.calcsize(fmt),
                          TPM2_CC_START_AUTH_SESSION,
                          TPM2_RH_NULL,
                          TPM2_RH_NULL,
                          16,
                          ('\0' * 16).encode(),
                          0,
                          session_type,
                          TPM2_ALG_NULL,
                          name_alg)

        return struct.unpack('>I', self.send_cmd(cmd)[10:14])[0]

    def __calc_pcr_digest(self, pcrs, bank_alg = TPM2_ALG_SHA1,
                          digest_alg = TPM2_ALG_SHA1):
        x = []
        f = get_hash_function(digest_alg)

        for i in pcrs:
            pcr = self.read_pcr(i, bank_alg)
            if pcr is None:
                return None
            x += pcr

        return f(bytearray(x)).digest()

    def policy_pcr(self, handle, pcrs, bank_alg = TPM2_ALG_SHA1,
                   name_alg = TPM2_ALG_SHA1):
        ds = get_digest_size(name_alg)
        dig = self.__calc_pcr_digest(pcrs, bank_alg, name_alg)
        if not dig:
            raise UnknownPCRBankError(bank_alg)

        pcrsel_len = max((max(pcrs) >> 3) + 1, 3)
        pcrsel = [0] * pcrsel_len
        for i in pcrs:
            pcrsel[i >> 3] |= 1 << (i & 7)
        pcrsel = ''.join(map(chr, pcrsel)).encode()

        fmt = '>HII IH%usIHB3s' % ds
        cmd = struct.pack(fmt,
                          TPM2_ST_NO_SESSIONS,
                          struct.calcsize(fmt),
                          TPM2_CC_POLICY_PCR,
                          handle,
                          len(dig),
                          bytes(dig),
                          1,
                          bank_alg,
                          pcrsel_len, pcrsel)

        self.send_cmd(cmd)

    def policy_password(self, handle):
        fmt = '>HII I'
        cmd = struct.pack(fmt,
                          TPM2_ST_NO_SESSIONS,
                          struct.calcsize(fmt),
                          TPM2_CC_POLICY_PASSWORD,
                          handle)

        self.send_cmd(cmd)

    def get_policy_digest(self, handle):
        fmt = '>HII I'
        cmd = struct.pack(fmt,
                          TPM2_ST_NO_SESSIONS,
                          struct.calcsize(fmt),
                          TPM2_CC_POLICY_GET_DIGEST,
                          handle)

        return self.send_cmd(cmd)[12:]

    def flush_context(self, handle):
        fmt = '>HIII'
        cmd = struct.pack(fmt,
                          TPM2_ST_NO_SESSIONS,
                          struct.calcsize(fmt),
                          TPM2_CC_FLUSH_CONTEXT,
                          handle)

        self.send_cmd(cmd)

    def create_root_key(self, auth_value = bytes()):
        attributes = \
            Public.FIXED_TPM | \
            Public.FIXED_PARENT | \
            Public.SENSITIVE_DATA_ORIGIN | \
            Public.USER_WITH_AUTH | \
            Public.RESTRICTED | \
            Public.DECRYPT

        auth_cmd = AuthCommand()
        sensitive = SensitiveCreate(user_auth=auth_value)

        public_parms = struct.pack(
            '>HHHHHI',
            TPM2_ALG_AES,
            128,
            TPM2_ALG_CFB,
            TPM2_ALG_NULL,
            2048,
            0)

        public = Public(
            object_type=TPM2_ALG_RSA,
            name_alg=TPM2_ALG_SHA1,
            object_attributes=attributes,
            parameters=public_parms)

        fmt = '>HIII I%us H%us H%us HI' % \
            (len(auth_cmd), len(sensitive), len(public))
        cmd = struct.pack(
            fmt,
            TPM2_ST_SESSIONS,
            struct.calcsize(fmt),
            TPM2_CC_CREATE_PRIMARY,
            TPM2_RH_OWNER,
            len(auth_cmd),
            bytes(auth_cmd),
            len(sensitive),
            bytes(sensitive),
            len(public),
            bytes(public),
            0, 0)

        return struct.unpack('>I', self.send_cmd(cmd)[10:14])[0]

    def seal(self, parent_key, data, auth_value, policy_dig,
             name_alg = TPM2_ALG_SHA1):
        ds = get_digest_size(name_alg)
        assert(not policy_dig or ds == len(policy_dig))

        attributes = 0
        if not policy_dig:
            attributes |= Public.USER_WITH_AUTH
            policy_dig = bytes()

        auth_cmd =  AuthCommand()
        sensitive = SensitiveCreate(user_auth=auth_value, data=data)

        public = Public(
            object_type=TPM2_ALG_KEYEDHASH,
            name_alg=name_alg,
            object_attributes=attributes,
            auth_policy=policy_dig,
            parameters=struct.pack('>H', TPM2_ALG_NULL))

        fmt = '>HIII I%us H%us H%us HI' % \
            (len(auth_cmd), len(sensitive), len(public))
        cmd = struct.pack(
            fmt,
            TPM2_ST_SESSIONS,
            struct.calcsize(fmt),
            TPM2_CC_CREATE,
            parent_key,
            len(auth_cmd),
            bytes(auth_cmd),
            len(sensitive),
            bytes(sensitive),
            len(public),
            bytes(public),
            0, 0)

        rsp = self.send_cmd(cmd)

        return rsp[14:]

    def unseal(self, parent_key, blob, auth_value, policy_handle):
        private_len = struct.unpack('>H', blob[0:2])[0]
        public_start = private_len + 2
        public_len = struct.unpack('>H', blob[public_start:public_start + 2])[0]
        blob = blob[:private_len + public_len + 4]

        auth_cmd = AuthCommand()

        fmt = '>HII I I%us %us' % (len(auth_cmd), len(blob))
        cmd = struct.pack(
            fmt,
            TPM2_ST_SESSIONS,
            struct.calcsize(fmt),
            TPM2_CC_LOAD,
            parent_key,
            len(auth_cmd),
            bytes(auth_cmd),
            blob)

        data_handle = struct.unpack('>I', self.send_cmd(cmd)[10:14])[0]

        if policy_handle:
            auth_cmd = AuthCommand(session_handle=policy_handle, hmac=auth_value)
        else:
            auth_cmd = AuthCommand(hmac=auth_value)

        fmt = '>HII I I%us' % (len(auth_cmd))
        cmd = struct.pack(
            fmt,
            TPM2_ST_SESSIONS,
            struct.calcsize(fmt),
            TPM2_CC_UNSEAL,
            data_handle,
            len(auth_cmd),
            bytes(auth_cmd))

        try:
            rsp = self.send_cmd(cmd)
        finally:
            self.flush_context(data_handle)

        data_len = struct.unpack('>I', rsp[10:14])[0] - 2

        return rsp[16:16 + data_len]

    def reset_da_lock(self):
        auth_cmd = AuthCommand()

        fmt = '>HII I I%us' % (len(auth_cmd))
        cmd = struct.pack(
            fmt,
            TPM2_ST_SESSIONS,
            struct.calcsize(fmt),
            TPM2_CC_DICTIONARY_ATTACK_LOCK_RESET,
            TPM2_RH_LOCKOUT,
            len(auth_cmd),
            bytes(auth_cmd))

        self.send_cmd(cmd)

    def __get_cap_cnt(self, cap, pt, cnt):
        handles = []
        fmt = '>HII III'

        cmd = struct.pack(fmt,
                          TPM2_ST_NO_SESSIONS,
                          struct.calcsize(fmt),
                          TPM2_CC_GET_CAPABILITY,
                          cap, pt, cnt)

        rsp = self.send_cmd(cmd)[10:]
        more_data, cap, cnt = struct.unpack('>BII', rsp[:9])
        rsp = rsp[9:]

        for i in range(0, cnt):
            handle = struct.unpack('>I', rsp[:4])[0]
            handles.append(handle)
            rsp = rsp[4:]

        return handles, more_data

    def get_cap(self, cap, pt):
        handles = []

        more_data = True
        while more_data:
            next_handles, more_data = self.__get_cap_cnt(cap, pt, 1)
            handles += next_handles
            pt += 1

        return handles