1tpm2_createak(1) General Commands Manual tpm2_createak(1)
2
6 tpm2_createak(1) - Generate attestation key with given algorithm under
7 the endorsement hierarchy.
8
10 tpm2_createak [OPTIONS]
11
13 tpm2_createak(1) - Generate an attestation key (AK) with the given al‐
14 gorithm under the endorsement hierarchy. The context of the attesta‐
15 tion key is specified via -c.
16 The tool outputs to stdout a YAML representation of the loaded key's
18 name, for example:
19 loaded-key:
21 name: 000bac149518baa05540a0678bd9b624f8a98d042e46c60f4d098ba394d36fc49268
22
24 · -P, --eh-auth=AUTH:
25 The authorization value for the endorsement hierarchy.
27 · -p, --ak-auth=AUTH
29 The authorization value for the attestation key object created.
31 · -C, --ek-context=OBJECT:
33 The endorsement key object.
35 · -c, --ak-context=FILE:
37 The file path to save the object context of the attestation key.
39 · -G, --key-algorithm=ALGORITHM:
41 Specifies the attestation key algorithm. Supports:
42 · ecc - An P256 key.
44 · rsa - An RSA2048 key.
46 · keyedhash - hmac key.
48 · -g, --hash-algorithm=ALGORITHM:
50 Specifies the digest algorithm used for signing.
52 · -s, --signing-algorithm=ALGORITHM:
54 The signing algorithm.
56 · -u, --public=FILE:
58 The file to save the public portion of the attestation key.
60 · -n, --ak-name=FILE:
62 The file to save the attestation key name, optional.
64 · -r, --private=FILE:
66 The output file which contains the sensitive portion of the object,
68 optional.
69 · -f, --format=FORMAT:
71 Format selection for the signature output file.
73 References
76 The type of a context object, whether it is a handle or file name, is
77 determined according to the following logic in-order:
78 · If the argument is a file path, then the file is loaded as a restored
80 TPM transient object.
81 · If the argument is a prefix match on one of:
83 · owner: the owner hierarchy
85 · platform: the platform hierarchy
87 · endorsement: the endorsement hierarchy
89 · lockout: the lockout control persistent object
91 · If the argument argument can be loaded as a number it will be treat
93 as a handle, e.g. 0x81010013 and used directly.OBJECT.
94
96 Authorization for use of an object in TPM2.0 can come in 3 different
97 forms: 1. Password 2. HMAC 3. Sessions
98 NOTE: "Authorizations default to the EMPTY PASSWORD when not speci‐
100 fied".
101 Passwords
103 Passwords are interpreted in the following forms below using prefix
104 identifiers.
105 Note: By default passwords are assumed to be in the string form when
107 they do not have a prefix.
108 String
110 A string password, specified by prefix "str:" or it's absence (raw
111 string without prefix) is not interpreted, and is directly used for au‐
112 thorization.
113 Examples
115 foobar
116 str:foobar
117 Hex-string
119 A hex-string password, specified by prefix "hex:" is converted from a
120 hexidecimal form into a byte array form, thus allowing passwords with
121 non-printable and/or terminal un-friendly characters.
122 Example
124 hex:0x1122334455667788
125 File
127 A file based password, specified be prefix "file:" should be the path
128 of a file containing the password to be read by the tool or a "-" to
129 use stdin. Storing passwords in files prevents information leakage,
130 passwords passed as options can be read from the process list or common
131 shell history features.
132 Examples
134 # to use stdin and be prompted
135 file:-
136 # to use a file from a path
138 file:path/to/password/file
139 # to echo a password via stdin:
141 echo foobar | tpm2_tool -p file:-
142 # to use a bash here-string via stdin:
144 tpm2_tool -p file:- <<< foobar
146 Sessions
148 When using a policy session to authorize the use of an object, prefix
149 the option argument with the session keyword. Then indicate a path to
150 a session file that was created with tpm2_startauthsession(1). Option‐
151 ally, if the session requires an auth value to be sent with the session
152 handle (eg policy password), then append a + and a string as described
153 in the Passwords section.
154 Examples
156 To use a session context file called session.ctx.
157 session:session.ctx
159 To use a session context file called session.ctx AND send the authvalue
161 mypassword.
162 session:session.ctx+mypassword
164 To use a session context file called session.ctx AND send the HEX auth‐
166 value 0x11223344.
167 session:session.ctx+hex:11223344
169 PCR Authorizations
171 You can satisfy a PCR policy using the "pcr:" prefix and the PCR mini‐
172 language. The PCR minilanguage is as follows:
173 <pcr-spec>=<raw-pcr-file>
174 The PCR spec is documented in in the section "PCR bank specifiers".
176 The raw-pcr-file is an optional the output of the raw PCR contents as
178 returned by tpm2_pcrread(1).
179 PCR bank specifiers (common/pcr.md)
181 Examples
183 To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifi‐
184 er of:
185 pcr:sha256:0,1,2,3
187 specifying AUTH.
189
191 Options that take algorithms support "nice-names".
192 There are two major algorithm specification string classes, simple and
194 complex. Only certain algorithms will be accepted by the TPM, based on
195 usage and conditions.
196 Simple specifiers
198 These are strings with no additional specification data. When creating
199 objects, non-specified portions of an object are assumed to defaults.
200 You can find the list of known "Simple Specifiers Below".
201 Asymmetric
203 · rsa
204 · ecc
206 Symmetric
208 · aes
209 · camellia
211 Hashing Algorithms
213 · sha1
214 · sha256
216 · sha384
218 · sha512
220 · sm3_256
222 · sha3_256
224 · sha3_384
226 · sha3_512
228 Keyed Hash
230 · hmac
231 · xor
233 Signing Schemes
235 · rsassa
236 · rsapss
238 · ecdsa
240 · ecdaa
242 · ecschnorr
244 Asymmetric Encryption Schemes
246 · oaep
247 · rsaes
249 · ecdh
251 Modes
253 · ctr
254 · ofb
256 · cbc
258 · cfb
260 · ecb
262 Misc
264 · null
265 Complex Specifiers
267 Objects, when specified for creation by the TPM, have numerous algo‐
268 rithms to populate in the public data. Things like type, scheme and
269 asymmetric details, key size, etc. Below is the general format for
270 specifying this data: <type>:<scheme>:<symmetric-details>
271 Type Specifiers
273 This portion of the complex algorithm specifier is required. The re‐
274 maining scheme and symmetric details will default based on the type
275 specified and the type of the object being created.
276 · aes - Default AES: aes128
278 · aes128<mode> - 128 bit AES with optional mode (ctr|ofb|cbc|cfb|ecb).
280 If mode is not specified, defaults to null.
281 · aes192<mode> - Same as aes128<mode>, except for a 192 bit key size.
283 · aes256<mode> - Same as aes128<mode>, except for a 256 bit key size.
285 · ecc - Elliptical Curve, defaults to ecc256.
287 · ecc192 - 192 bit ECC
289 · ecc224 - 224 bit ECC
291 · ecc256 - 256 bit ECC
293 · ecc384 - 384 bit ECC
295 · ecc521 - 521 bit ECC
297 · rsa - Default RSA: rsa2048
299 · rsa1024 - RSA with 1024 bit keysize.
301 · rsa2048 - RSA with 2048 bit keysize.
303 · rsa4096 - RSA with 4096 bit keysize.
305 Scheme Specifiers
307 Next, is an optional field, it can be skipped.
308 Schemes are usually Signing Schemes or Asymmetric Encryption Schemes.
310 Most signing schemes take a hash algorithm directly following the sign‐
311 ing scheme. If the hash algorithm is missing, it defaults to sha256.
312 Some take no arguments, and some take multiple arguments.
313 Hash Optional Scheme Specifiers
315 These scheme specifiers are followed by a dash and a valid hash algo‐
316 rithm, For example: oaep-sha256.
317 · oaep
319 · ecdh
321 · rsassa
323 · rsapss
325 · ecdsa
327 · ecschnorr
329 Multiple Option Scheme Specifiers
331 This scheme specifier is followed by a count (max size UINT16) then
332 folloed by a dash(-) and a valid hash algorithm. * ecdaa For example,
333 ecdaa4-sha256. If no count is specified, it defaults to 4.
334 No Option Scheme Specifiers
336 This scheme specifier takes NO arguments. * rsaes
337 Symmetric Details Specifiers
339 This field is optional, and defaults based on the type of object being
340 created and it's attributes. Generally, any valid Symmetric specifier
341 from the Type Specifiers list should work. If not specified, an asym‐
342 metric objects symmetric details defaults to aes128cfb.
343 Examples
345 Create an rsa2048 key with an rsaes asymmetric encryption scheme
346 tpm2_create -C parent.ctx -G rsa2048:rsaes -u key.pub -r key.priv
347 Create an ecc256 key with an ecdaa signing scheme with a count of 4
349 and sha384 hash
350 /tpm2_create -C parent.ctx -G ecc256:ec‐
352 daa4-sha384 -u key.pub -r key.priv cryptographic algorithms ALGORITHM.
353
355 Format selection for the signature output file. tss (the default) will
356 output a binary blob according to the TPM 2.0 specification and any po‐
357 tential compiler padding. The option plain will output the plain sig‐
358 nature data as defined by the used cryptographic algorithm. signature
359 FORMAT.
360
362 This collection of options are common to many programs and provide in‐
363 formation that many users may expect.
364 · -h, --help=[man|no-man]: Display the tools manpage. By default, it
366 attempts to invoke the manpager for the tool, however, on failure
367 will output a short tool summary. This is the same behavior if the
368 "man" option argument is specified, however if explicit "man" is re‐
369 quested, the tool will provide errors from man on stderr. If the
370 "no-man" option if specified, or the manpager fails, the short op‐
371 tions will be output to stdout.
372 To successfully use the manpages feature requires the manpages to be
374 installed or on MANPATH, See man(1) for more details.
375 · -v, --version: Display version information for this tool, supported
377 tctis and exit.
378 · -V, --verbose: Increase the information that the tool prints to the
380 console during its execution. When using this option the file and
381 line number are printed.
382 · -Q, --quiet: Silence normal tool output to stdout.
384 · -Z, --enable-errata: Enable the application of errata fixups. Useful
386 if an errata fixup needs to be applied to commands sent to the TPM.
387 Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent. in‐
388 formation many users may expect.
389
391 The TCTI or "Transmission Interface" is the communication mechanism
392 with the TPM. TCTIs can be changed for communication with TPMs across
393 different mediums.
394 To control the TCTI, the tools respect:
396 1. The command line option -T or --tcti
398 2. The environment variable: TPM2TOOLS_TCTI.
400 Note: The command line option always overrides the environment vari‐
402 able.
403 The current known TCTIs are:
405 · tabrmd - The resource manager, called tabrmd
407 (https://github.com/tpm2-software/tpm2-abrmd). Note that tabrmd and
408 abrmd as a tcti name are synonymous.
409 · mssim - Typically used for communicating to the TPM software simula‐
411 tor.
412 · device - Used when talking directly to a TPM device file.
414 · none - Do not initalize a connection with the TPM. Some tools allow
416 for off-tpm options and thus support not using a TCTI. Tools that do
417 not support it will error when attempted to be used without a TCTI
418 connection. Does not support ANY options and MUST BE presented as
419 the exact text of "none".
420 The arguments to either the command line option or the environment
422 variable are in the form:
423 <tcti-name>:<tcti-option-config>
425 Specifying an empty string for either the <tcti-name> or <tcti-op‐
427 tion-config> results in the default being used for that portion respec‐
428 tively.
429 TCTI Defaults
431 When a TCTI is not specified, the default TCTI is searched for using
432 dlopen(3) semantics. The tools will search for tabrmd, device and
433 mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND. You can query
434 what TCTI will be chosen as the default by using the -v option to print
435 the version information. The "default-tcti" key-value pair will indi‐
436 cate which of the aforementioned TCTIs is the default.
437 Custom TCTIs
439 Any TCTI that implements the dynamic TCTI interface can be loaded. The
440 tools internally use dlopen(3), and the raw tcti-name value is used for
441 the lookup. Thus, this could be a path to the shared library, or a li‐
442 brary name as understood by dlopen(3) semantics.
443
445 This collection of options are used to configure the various known TCTI
446 modules available:
447 · device: For the device TCTI, the TPM character device file for use by
449 the device TCTI can be specified. The default is /dev/tpm0.
450 Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI="de‐
452 vice:/dev/tpm0"
453 · mssim: For the mssim TCTI, the domain name or IP address and port
455 number used by the simulator can be specified. The default are
456 127.0.0.1 and 2321.
457 Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TC‐
459 TI="mssim:host=localhost,port=2321"
460 · abrmd: For the abrmd TCTI, the configuration string format is a se‐
462 ries of simple key value pairs separated by a ',' character. Each
463 key and value string are separated by a '=' character.
464 · TCTI abrmd supports two keys:
466 1. 'bus_name' : The name of the tabrmd service on the bus (a
468 string).
469 2. 'bus_type' : The type of the dbus instance (a string) limited to
471 'session' and 'system'.
472 Specify the tabrmd tcti name and a config string of bus_name=com.ex‐
474 ample.FooBar:
475 \--tcti=tabrmd:bus_name=com.example.FooBar
477 Specify the default (abrmd) tcti and a config string of bus_type=ses‐
479 sion:
480 \--tcti:bus_type=session
482 NOTE: abrmd and tabrmd are synonymous. the various known TCTI mod‐
484 ules.
485
487 Create an Attestation Key and make it persistent
488 tpm2_createek -c ek.handle -G rsa -u ek.pub
489 tpm2_createak -C ek.handle -c ak.ctx -u ak.pub -n ak.name
490 tpm2_evictcontrol -c 0x81010002 -o ak.ctx
491
493 Tools can return any of the following codes:
494 · 0 - Success.
496 · 1 - General non-specific error.
498 · 2 - Options handling error.
500 · 3 - Authentication error.
502 · 4 - TCTI related error.
504 · 5 - Non supported scheme. Applicable to tpm2_testparams.
506
508 Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
509
511 See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)
512tpm2-tools tpm2_createak(1)