1tpm2_hmac(1) General Commands Manual tpm2_hmac(1)
2
6 tpm2_hmac(1) - Performs an HMAC operation with the TPM.
7
9 tpm2_hmac [OPTIONS] [ARGUMENT]
10
12 tpm2_hmac(1) - Performs an HMAC operation and returns the results. If
13 argument file is not specified, then data is read from stdin.
14 The hashing algorithm defaults to the keys scheme or sha256 if the key
16 has a NULL scheme.
17 Output defaults to STDOUT and binary format unless otherwise specified
19 via -o and --hex options respectively.
20
22 · -c, --key-context=OBJECT:
23 The context object of the symmetric signing key providing the HMAC
25 key. Either a file or a handle number. See section "Context Object
26 Format".
27 · -p, --auth=AUTH:
29 Optional authorization value to use the key specified by -c.
31 · -g, --hash-algorithm=ALGORITHM:
33 The hash algorithm to use. Algorithms should follow the "formatting
35 standards", see section "Algorithm Specifiers". Also, see section
36 "Supported Hash Algorithms" for a list of supported hash algorithms.
37 · --hex
39 Convert the output hmac to hex format without a leading "0x".
41 · -o, --output=FILE:
43 Optional file record of the HMAC result. Defaults to STDOUT.
45 · -t, --ticket=FILE:
47 Optional file record of the ticket result.
49 · ARGUMENT the command line argument specifies the file path for the
51 data to HMAC. Defaults to STDIN if not specified.
52 References
55 The type of a context object, whether it is a handle or file name, is
56 determined according to the following logic in-order:
57 · If the argument is a file path, then the file is loaded as a restored
59 TPM transient object.
60 · If the argument is a prefix match on one of:
62 · owner: the owner hierarchy
64 · platform: the platform hierarchy
66 · endorsement: the endorsement hierarchy
68 · lockout: the lockout control persistent object
70 · If the argument argument can be loaded as a number it will be treat
72 as a handle, e.g. 0x81010013 and used directly.OBJECT.
73
75 Authorization for use of an object in TPM2.0 can come in 3 different
76 forms: 1. Password 2. HMAC 3. Sessions
77 NOTE: "Authorizations default to the EMPTY PASSWORD when not speci‐
79 fied".
80 Passwords
82 Passwords are interpreted in the following forms below using prefix
83 identifiers.
84 Note: By default passwords are assumed to be in the string form when
86 they do not have a prefix.
87 String
89 A string password, specified by prefix "str:" or it's absence (raw
90 string without prefix) is not interpreted, and is directly used for au‐
91 thorization.
92 Examples
94 foobar
95 str:foobar
96 Hex-string
98 A hex-string password, specified by prefix "hex:" is converted from a
99 hexidecimal form into a byte array form, thus allowing passwords with
100 non-printable and/or terminal un-friendly characters.
101 Example
103 hex:0x1122334455667788
104 File
106 A file based password, specified be prefix "file:" should be the path
107 of a file containing the password to be read by the tool or a "-" to
108 use stdin. Storing passwords in files prevents information leakage,
109 passwords passed as options can be read from the process list or common
110 shell history features.
111 Examples
113 # to use stdin and be prompted
114 file:-
115 # to use a file from a path
117 file:path/to/password/file
118 # to echo a password via stdin:
120 echo foobar | tpm2_tool -p file:-
121 # to use a bash here-string via stdin:
123 tpm2_tool -p file:- <<< foobar
125 Sessions
127 When using a policy session to authorize the use of an object, prefix
128 the option argument with the session keyword. Then indicate a path to
129 a session file that was created with tpm2_startauthsession(1). Option‐
130 ally, if the session requires an auth value to be sent with the session
131 handle (eg policy password), then append a + and a string as described
132 in the Passwords section.
133 Examples
135 To use a session context file called session.ctx.
136 session:session.ctx
138 To use a session context file called session.ctx AND send the authvalue
140 mypassword.
141 session:session.ctx+mypassword
143 To use a session context file called session.ctx AND send the HEX auth‐
145 value 0x11223344.
146 session:session.ctx+hex:11223344
148 PCR Authorizations
150 You can satisfy a PCR policy using the "pcr:" prefix and the PCR mini‐
151 language. The PCR minilanguage is as follows:
152 <pcr-spec>=<raw-pcr-file>
153 The PCR spec is documented in in the section "PCR bank specifiers".
155 The raw-pcr-file is an optional the output of the raw PCR contents as
157 returned by tpm2_pcrread(1).
158 PCR bank specifiers (common/pcr.md)
160 Examples
162 To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifi‐
163 er of:
164 pcr:sha256:0,1,2,3
166 specifying AUTH.
168
170 Authorization for use of an object in TPM2.0 can come in 3 different
171 forms: 1. Password 2. HMAC 3. Sessions
172 NOTE: "Authorizations default to the EMPTY PASSWORD when not speci‐
174 fied".
175 Passwords
177 Passwords are interpreted in the following forms below using prefix
178 identifiers.
179 Note: By default passwords are assumed to be in the string form when
181 they do not have a prefix.
182 String
184 A string password, specified by prefix "str:" or it's absence (raw
185 string without prefix) is not interpreted, and is directly used for au‐
186 thorization.
187 Examples
189 foobar
190 str:foobar
191 Hex-string
193 A hex-string password, specified by prefix "hex:" is converted from a
194 hexidecimal form into a byte array form, thus allowing passwords with
195 non-printable and/or terminal un-friendly characters.
196 Example
198 hex:0x1122334455667788
199 File
201 A file based password, specified be prefix "file:" should be the path
202 of a file containing the password to be read by the tool or a "-" to
203 use stdin. Storing passwords in files prevents information leakage,
204 passwords passed as options can be read from the process list or common
205 shell history features.
206 Examples
208 # to use stdin and be prompted
209 file:-
210 # to use a file from a path
212 file:path/to/password/file
213 # to echo a password via stdin:
215 echo foobar | tpm2_tool -p file:-
216 # to use a bash here-string via stdin:
218 tpm2_tool -p file:- <<< foobar
220 Sessions
222 When using a policy session to authorize the use of an object, prefix
223 the option argument with the session keyword. Then indicate a path to
224 a session file that was created with tpm2_startauthsession(1). Option‐
225 ally, if the session requires an auth value to be sent with the session
226 handle (eg policy password), then append a + and a string as described
227 in the Passwords section.
228 Examples
230 To use a session context file called session.ctx.
231 session:session.ctx
233 To use a session context file called session.ctx AND send the authvalue
235 mypassword.
236 session:session.ctx+mypassword
238 To use a session context file called session.ctx AND send the HEX auth‐
240 value 0x11223344.
241 session:session.ctx+hex:11223344
243 PCR Authorizations
245 You can satisfy a PCR policy using the "pcr:" prefix and the PCR mini‐
246 language. The PCR minilanguage is as follows:
247 <pcr-spec>=<raw-pcr-file>
248 The PCR spec is documented in in the section "PCR bank specifiers".
250 The raw-pcr-file is an optional the output of the raw PCR contents as
252 returned by tpm2_pcrread(1).
253 PCR bank specifiers (common/pcr.md)
255 Examples
257 To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifi‐
258 er of:
259 pcr:sha256:0,1,2,3
261 ALGORITHM.
263
265 This collection of options are common to many programs and provide in‐
266 formation that many users may expect.
267 · -h, --help=[man|no-man]: Display the tools manpage. By default, it
269 attempts to invoke the manpager for the tool, however, on failure
270 will output a short tool summary. This is the same behavior if the
271 "man" option argument is specified, however if explicit "man" is re‐
272 quested, the tool will provide errors from man on stderr. If the
273 "no-man" option if specified, or the manpager fails, the short op‐
274 tions will be output to stdout.
275 To successfully use the manpages feature requires the manpages to be
277 installed or on MANPATH, See man(1) for more details.
278 · -v, --version: Display version information for this tool, supported
280 tctis and exit.
281 · -V, --verbose: Increase the information that the tool prints to the
283 console during its execution. When using this option the file and
284 line number are printed.
285 · -Q, --quiet: Silence normal tool output to stdout.
287 · -Z, --enable-errata: Enable the application of errata fixups. Useful
289 if an errata fixup needs to be applied to commands sent to the TPM.
290 Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent. in‐
291 formation many users may expect.
292
294 The TCTI or "Transmission Interface" is the communication mechanism
295 with the TPM. TCTIs can be changed for communication with TPMs across
296 different mediums.
297 To control the TCTI, the tools respect:
299 1. The command line option -T or --tcti
301 2. The environment variable: TPM2TOOLS_TCTI.
303 Note: The command line option always overrides the environment vari‐
305 able.
306 The current known TCTIs are:
308 · tabrmd - The resource manager, called tabrmd
310 (https://github.com/tpm2-software/tpm2-abrmd). Note that tabrmd and
311 abrmd as a tcti name are synonymous.
312 · mssim - Typically used for communicating to the TPM software simula‐
314 tor.
315 · device - Used when talking directly to a TPM device file.
317 · none - Do not initalize a connection with the TPM. Some tools allow
319 for off-tpm options and thus support not using a TCTI. Tools that do
320 not support it will error when attempted to be used without a TCTI
321 connection. Does not support ANY options and MUST BE presented as
322 the exact text of "none".
323 The arguments to either the command line option or the environment
325 variable are in the form:
326 <tcti-name>:<tcti-option-config>
328 Specifying an empty string for either the <tcti-name> or <tcti-op‐
330 tion-config> results in the default being used for that portion respec‐
331 tively.
332 TCTI Defaults
334 When a TCTI is not specified, the default TCTI is searched for using
335 dlopen(3) semantics. The tools will search for tabrmd, device and
336 mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND. You can query
337 what TCTI will be chosen as the default by using the -v option to print
338 the version information. The "default-tcti" key-value pair will indi‐
339 cate which of the aforementioned TCTIs is the default.
340 Custom TCTIs
342 Any TCTI that implements the dynamic TCTI interface can be loaded. The
343 tools internally use dlopen(3), and the raw tcti-name value is used for
344 the lookup. Thus, this could be a path to the shared library, or a li‐
345 brary name as understood by dlopen(3) semantics.
346
348 This collection of options are used to configure the various known TCTI
349 modules available:
350 · device: For the device TCTI, the TPM character device file for use by
352 the device TCTI can be specified. The default is /dev/tpm0.
353 Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI="de‐
355 vice:/dev/tpm0"
356 · mssim: For the mssim TCTI, the domain name or IP address and port
358 number used by the simulator can be specified. The default are
359 127.0.0.1 and 2321.
360 Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TC‐
362 TI="mssim:host=localhost,port=2321"
363 · abrmd: For the abrmd TCTI, the configuration string format is a se‐
365 ries of simple key value pairs separated by a ',' character. Each
366 key and value string are separated by a '=' character.
367 · TCTI abrmd supports two keys:
369 1. 'bus_name' : The name of the tabrmd service on the bus (a
371 string).
372 2. 'bus_type' : The type of the dbus instance (a string) limited to
374 'session' and 'system'.
375 Specify the tabrmd tcti name and a config string of bus_name=com.ex‐
377 ample.FooBar:
378 \--tcti=tabrmd:bus_name=com.example.FooBar
380 Specify the default (abrmd) tcti and a config string of bus_type=ses‐
382 sion:
383 \--tcti:bus_type=session
385 NOTE: abrmd and tabrmd are synonymous. the various known TCTI mod‐
387 ules.
388
390 Setup
391 # create a primary object
392 tpm2_createprimary -o primary.ctx
393 # create an hmac key
395 tpm2_create -C primary.ctx -Ghmac -o hmac.key
396 Perform an HMAC with Default Hash Algorithm
398 Perform an hmac using the key's default scheme (hash algorithm) and
399 output to stdout in hexidecimal format.
400 tpm2_hmac -c hmac.key --hex data.in
402 e6eda48a53a9ddbb92f788f6d98e0372d63a408afb11aca43f522a2475a32805
403
405 Tools can return any of the following codes:
406 · 0 - Success.
408 · 1 - General non-specific error.
410 · 2 - Options handling error.
412 · 3 - Authentication error.
414 · 4 - TCTI related error.
416 · 5 - Non supported scheme. Applicable to tpm2_testparams.
418
420 Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
421
423 See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)
424tpm2-tools tpm2_hmac(1)