1tpm2_unseal(1)              General Commands Manual             tpm2_unseal(1)
2
3
4

NAME

6       tpm2_unseal(1)  - Returns a data blob in a loaded TPM object.  The data
7       blob is returned in clear.
8

SYNOPSIS

10       tpm2_unseal [OPTIONS]
11

DESCRIPTION

13       tpm2_unseal(1) - Returns a data blob in a loaded TPM object.  The  data
14       blob  is  returned in clear.  The data is sealed at the time of the ob‐
15       ject creation using the tpm2_create tool.  Such an object intended  for
16       sealing data has to be of the type TPM_ALG_KEYEDHASH.
17

OPTIONS

19-c, --object-context=OBJECT:
20
21         Object context for the loaded object.
22
23-p, --auth=AUTH:
24
25         Optional auth value to use for the key specified by -c.
26
27-o, --output=FILE:
28
29         Output file name containing the unsealed data.  Defaults to STDOUT if
30         not specified.
31
32--cphash=FILE
33
34         File path to record the hash of the command parameters.  This is com‐
35         monly termed as cpHash.  NOTE: When this option is selected, The tool
36         will not actually execute the command, it simply returns a cpHash, it
37         simply returns a cpHash, unless rphash is also required.
38
39--rphash=FILE
40
41         File  path  to  record  the hash of the response parameters.  This is
42         commonly termed as rpHash.
43
44-S, --session=FILE:
45
46         The session created using tpm2_startauthsession.  Multiple  of  these
47         can be specified.  For example, you can have one session for auditing
48         and another for encryption/decryption of the parameters.
49
50   References

Context Object Format

52       The type of a context object, whether it is a handle or file  name,  is
53       determined according to the following logic in-order:
54
55       • If the argument is a file path, then the file is loaded as a restored
56         TPM transient object.
57
58       • If the argument is a prefix match on one of:
59
60         • owner: the owner hierarchy
61
62         • platform: the platform hierarchy
63
64         • endorsement: the endorsement hierarchy
65
66         • lockout: the lockout control persistent object
67
68       • If the argument argument can be loaded as a number it will  be  treat
69         as a handle, e.g. 0x81010013 and used directly._OBJECT_.
70

Authorization Formatting

72       Authorization  for  use  of an object in TPM2.0 can come in 3 different
73       forms: 1.  Password 2.  HMAC 3.  Sessions
74
75       NOTE: “Authorizations default to the EMPTY  PASSWORD  when  not  speci‐
76       fied”.
77
78   Passwords
79       Passwords  are  interpreted  in  the following forms below using prefix
80       identifiers.
81
82       Note: By default passwords are assumed to be in the  string  form  when
83       they do not have a prefix.
84
85   String
86       A  string  password,  specified  by  prefix “str:” or it’s absence (raw
87       string without prefix) is not interpreted, and is directly used for au‐
88       thorization.
89
90   Examples
91              foobar
92              str:foobar
93
94   Hex-string
95       A  hex-string  password, specified by prefix “hex:” is converted from a
96       hexidecimal form into a byte array form, thus allowing  passwords  with
97       non-printable and/or terminal un-friendly characters.
98
99   Example
100              hex:1122334455667788
101
102   File
103       A  file  based password, specified be prefix “file:” should be the path
104       of a file containing the password to be read by the tool or  a  “-”  to
105       use  stdin.   Storing  passwords in files prevents information leakage,
106       passwords passed as options can be read from the process list or common
107       shell history features.
108
109   Examples
110              # to use stdin and be prompted
111              file:-
112
113              # to use a file from a path
114              file:path/to/password/file
115
116              # to echo a password via stdin:
117              echo foobar | tpm2_tool -p file:-
118
119              # to use a bash here-string via stdin:
120
121              tpm2_tool -p file:- <<< foobar
122
123   Sessions
124       When  using  a policy session to authorize the use of an object, prefix
125       the option argument with the session keyword.  Then indicate a path  to
126       a session file that was created with tpm2_startauthsession(1).  Option‐
127       ally, if the session requires an auth value to be sent with the session
128       handle  (eg policy password), then append a + and a string as described
129       in the Passwords section.
130
131   Examples
132       To use a session context file called session.ctx.
133
134              session:session.ctx
135
136       To use a session context file called session.ctx AND send the authvalue
137       mypassword.
138
139              session:session.ctx+mypassword
140
141       To use a session context file called session.ctx AND send the HEX auth‐
142       value 0x11223344.
143
144              session:session.ctx+hex:11223344
145
146   PCR Authorizations
147       You can satisfy a PCR policy using the “pcr:” prefix and the PCR  mini‐
148       language.       The     PCR     minilanguage     is     as     follows:
149       <pcr-spec>=<raw-pcr-file>
150
151       The PCR spec is documented in in the section “PCR bank specifiers”.
152
153       The raw-pcr-file is an optional argument that contains  the  output  of
154       the raw PCR contents as returned by tpm2_pcrread(1).
155
156       PCR bank specifiers (pcr.md)
157
158   Examples
159       To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifi‐
160       er of:
161
162              pcr:sha256:0,1,2,3
163
164       specifying AUTH.
165

COMMON OPTIONS

167       This collection of options are common to many programs and provide  in‐
168       formation that many users may expect.
169
170-h,  --help=[man|no-man]:  Display the tools manpage.  By default, it
171         attempts to invoke the manpager for the  tool,  however,  on  failure
172         will  output  a short tool summary.  This is the same behavior if the
173         “man” option argument is specified, however if explicit “man” is  re‐
174         quested,  the  tool  will  provide errors from man on stderr.  If the
175         “no-man” option if specified, or the manpager fails,  the  short  op‐
176         tions will be output to stdout.
177
178         To  successfully use the manpages feature requires the manpages to be
179         installed or on MANPATH, See man(1) for more details.
180
181-v, --version: Display version information for this  tool,  supported
182         tctis and exit.
183
184-V,  --verbose:  Increase the information that the tool prints to the
185         console during its execution.  When using this option  the  file  and
186         line number are printed.
187
188-Q, --quiet: Silence normal tool output to stdout.
189
190-Z, --enable-errata: Enable the application of errata fixups.  Useful
191         if an errata fixup needs to be applied to commands sent to  the  TPM.
192         Defining  the environment TPM2TOOLS_ENABLE_ERRATA is equivalent.  in‐
193         formation many users may expect.
194

TCTI Configuration

196       The TCTI or “Transmission Interface”  is  the  communication  mechanism
197       with  the TPM.  TCTIs can be changed for communication with TPMs across
198       different mediums.
199
200       To control the TCTI, the tools respect:
201
202       1. The command line option -T or --tcti
203
204       2. The environment variable: TPM2TOOLS_TCTI.
205
206       Note: The command line option always overrides  the  environment  vari‐
207       able.
208
209       The current known TCTIs are:
210
211       • tabrmd      -     The     resource     manager,     called     tabrmd
212         (https://github.com/tpm2-software/tpm2-abrmd).  Note that tabrmd  and
213         abrmd as a tcti name are synonymous.
214
215       • mssim  - Typically used for communicating to the TPM software simula‐
216         tor.
217
218       • device - Used when talking directly to a TPM device file.
219
220       • none - Do not initalize a connection with the TPM.  Some tools  allow
221         for off-tpm options and thus support not using a TCTI.  Tools that do
222         not support it will error when attempted to be used  without  a  TCTI
223         connection.   Does  not  support ANY options and MUST BE presented as
224         the exact text of “none”.
225
226       The arguments to either the command  line  option  or  the  environment
227       variable are in the form:
228
229       <tcti-name>:<tcti-option-config>
230
231       Specifying  an  empty  string  for  either the <tcti-name> or <tcti-op‐
232       tion-config> results in the default being used for that portion respec‐
233       tively.
234
235   TCTI Defaults
236       When  a  TCTI  is not specified, the default TCTI is searched for using
237       dlopen(3) semantics.  The tools will  search  for  tabrmd,  device  and
238       mssim  TCTIs  IN THAT ORDER and USE THE FIRST ONE FOUND.  You can query
239       what TCTI will be chosen as the default by using the -v option to print
240       the  version information.  The “default-tcti” key-value pair will indi‐
241       cate which of the aforementioned TCTIs is the default.
242
243   Custom TCTIs
244       Any TCTI that implements the dynamic TCTI interface can be loaded.  The
245       tools internally use dlopen(3), and the raw tcti-name value is used for
246       the lookup.  Thus, this could be a path to the shared library, or a li‐
247       brary name as understood by dlopen(3) semantics.
248

TCTI OPTIONS

250       This collection of options are used to configure the various known TCTI
251       modules available:
252
253device: For the device TCTI, the TPM character device file for use by
254         the device TCTI can be specified.  The default is /dev/tpm0.
255
256         Example:    -T   device:/dev/tpm0   or   export   TPM2TOOLS_TCTI=“de‐
257         vice:/dev/tpm0”
258
259mssim: For the mssim TCTI, the domain name or  IP  address  and  port
260         number  used  by  the  simulator  can  be specified.  The default are
261         127.0.0.1 and 2321.
262
263         Example: -T mssim:host=localhost,port=2321  or  export  TPM2TOOLS_TC‐
264         TI=“mssim:host=localhost,port=2321”
265
266abrmd:  For  the abrmd TCTI, the configuration string format is a se‐
267         ries of simple key value pairs separated by a  `,'  character.   Each
268         key and value string are separated by a `=' character.
269
270         • TCTI abrmd supports two keys:
271
272           1. `bus_name'  :  The  name  of  the  tabrmd  service on the bus (a
273              string).
274
275           2. `bus_type' : The type of the dbus instance (a string) limited to
276              `session' and `system'.
277
278         Specify  the tabrmd tcti name and a config string of bus_name=com.ex‐
279         ample.FooBar:
280
281                \--tcti=tabrmd:bus_name=com.example.FooBar
282
283         Specify the default (abrmd) tcti and a config string of bus_type=ses‐
284         sion:
285
286                \--tcti:bus_type=session
287
288         NOTE:  abrmd  and tabrmd are synonymous.  the various known TCTI mod‐
289         ules.
290

EXAMPLES

292              tpm2_createprimary -c primary.ctx -Q
293
294              tpm2_pcrread -Q -o pcr.bin sha256:0,1,2,3
295
296              tpm2_createpolicy -Q --policy-pcr -l sha256:0,1,2,3 -f pcr.bin -L pcr.policy
297
298              echo 'secret' | tpm2_create -C primary.ctx -L pcr.policy -i-\
299              -u seal.pub -r seal.priv -c seal.ctx -Q
300
301              tpm2_unseal -c seal.ctx -p pcr:sha256:0,1,2,3
302

Returns

304       Tools can return any of the following codes:
305
306       • 0 - Success.
307
308       • 1 - General non-specific error.
309
310       • 2 - Options handling error.
311
312       • 3 - Authentication error.
313
314       • 4 - TCTI related error.
315
316       • 5 - Non supported scheme.  Applicable to tpm2_testparams.
317

BUGS

319       Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
320

HELP

322       See the Mailing List (https://lists.linuxfoundation.org/mailman/listin
323       fo/tpm2)
324
325
326
327tpm2-tools                                                      tpm2_unseal(1)
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