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   References

Context Object Format

34       The type of a context object, whether it is a handle or file  name,  is
35       determined according to the following logic in-order:
36
37       · If the argument is a file path, then the file is loaded as a restored
38         TPM transient object.
39
40       · If the argument is a prefix match on one of:
41
42         · owner: the owner hierarchy
43
44         · platform: the platform hierarchy
45
46         · endorsement: the endorsement hierarchy
47
48         · lockout: the lockout control persistent object
49
50       · If the argument argument can be loaded as a number it will  be  treat
51         as a handle, e.g.  0x81010013 and used directly.OBJECT.
52

Authorization Formatting

54       Authorization  for  use  of an object in TPM2.0 can come in 3 different
55       forms: 1.  Password 2.  HMAC 3.  Sessions
56
57       NOTE: "Authorizations default to the EMPTY  PASSWORD  when  not  speci‐
58       fied".
59
60   Passwords
61       Passwords  are  interpreted  in  the following forms below using prefix
62       identifiers.
63
64       Note: By default passwords are assumed to be in the  string  form  when
65       they do not have a prefix.
66
67   String
68       A  string  password,  specified  by  prefix "str:" or it's absence (raw
69       string without prefix) is not interpreted, and is directly used for au‐
70       thorization.
71
72   Examples
73              foobar
74              str:foobar
75
76   Hex-string
77       A  hex-string  password, specified by prefix "hex:" is converted from a
78       hexidecimal form into a byte array form, thus allowing  passwords  with
79       non-printable and/or terminal un-friendly characters.
80
81   Example
82              hex:0x1122334455667788
83
84   File
85       A  file  based password, specified be prefix "file:" should be the path
86       of a file containing the password to be read by the tool or  a  "-"  to
87       use  stdin.   Storing  passwords in files prevents information leakage,
88       passwords passed as options can be read from the process list or common
89       shell history features.
90
91   Examples
92              # to use stdin and be prompted
93              file:-
94
95              # to use a file from a path
96              file:path/to/password/file
97
98              # to echo a password via stdin:
99              echo foobar | tpm2_tool -p file:-
100
101              # to use a bash here-string via stdin:
102
103              tpm2_tool -p file:- <<< foobar
104
105   Sessions
106       When  using  a policy session to authorize the use of an object, prefix
107       the option argument with the session keyword.  Then indicate a path  to
108       a session file that was created with tpm2_startauthsession(1).  Option‐
109       ally, if the session requires an auth value to be sent with the session
110       handle  (eg policy password), then append a + and a string as described
111       in the Passwords section.
112
113   Examples
114       To use a session context file called session.ctx.
115
116              session:session.ctx
117
118       To use a session context file called session.ctx AND send the authvalue
119       mypassword.
120
121              session:session.ctx+mypassword
122
123       To use a session context file called session.ctx AND send the HEX auth‐
124       value 0x11223344.
125
126              session:session.ctx+hex:11223344
127
128   PCR Authorizations
129       You can satisfy a PCR policy using the "pcr:" prefix and the PCR  mini‐
130       language.       The     PCR     minilanguage     is     as     follows:
131       <pcr-spec>=<raw-pcr-file>
132
133       The PCR spec is documented in in the section "PCR bank specifiers".
134
135       The raw-pcr-file is an optional the output of the raw PCR  contents  as
136       returned by tpm2_pcrread(1).
137
138       PCR bank specifiers (common/pcr.md)
139
140   Examples
141       To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifi‐
142       er of:
143
144              pcr:sha256:0,1,2,3
145
146       specifying AUTH.
147

COMMON OPTIONS

149       This collection of options are common to many programs and provide  in‐
150       formation that many users may expect.
151
152       · -h,  --help=[man|no-man]:  Display the tools manpage.  By default, it
153         attempts to invoke the manpager for the  tool,  however,  on  failure
154         will  output  a short tool summary.  This is the same behavior if the
155         "man" option argument is specified, however if explicit "man" is  re‐
156         quested,  the  tool  will  provide errors from man on stderr.  If the
157         "no-man" option if specified, or the manpager fails,  the  short  op‐
158         tions will be output to stdout.
159
160         To  successfully use the manpages feature requires the manpages to be
161         installed or on MANPATH, See man(1) for more details.
162
163       · -v, --version: Display version information for this  tool,  supported
164         tctis and exit.
165
166       · -V,  --verbose:  Increase the information that the tool prints to the
167         console during its execution.  When using this option  the  file  and
168         line number are printed.
169
170       · -Q, --quiet: Silence normal tool output to stdout.
171
172       · -Z, --enable-errata: Enable the application of errata fixups.  Useful
173         if an errata fixup needs to be applied to commands sent to  the  TPM.
174         Defining  the environment TPM2TOOLS_ENABLE_ERRATA is equivalent.  in‐
175         formation many users may expect.
176

TCTI Configuration

178       The TCTI or "Transmission Interface"  is  the  communication  mechanism
179       with  the TPM.  TCTIs can be changed for communication with TPMs across
180       different mediums.
181
182       To control the TCTI, the tools respect:
183
184       1. The command line option -T or --tcti
185
186       2. The environment variable: TPM2TOOLS_TCTI.
187
188       Note: The command line option always overrides  the  environment  vari‐
189       able.
190
191       The current known TCTIs are:
192
193       · tabrmd      -     The     resource     manager,     called     tabrmd
194         (https://github.com/tpm2-software/tpm2-abrmd).  Note that tabrmd  and
195         abrmd as a tcti name are synonymous.
196
197       · mssim  - Typically used for communicating to the TPM software simula‐
198         tor.
199
200       · device - Used when talking directly to a TPM device file.
201
202       · none - Do not initalize a connection with the TPM.  Some tools  allow
203         for off-tpm options and thus support not using a TCTI.  Tools that do
204         not support it will error when attempted to be used  without  a  TCTI
205         connection.   Does  not  support ANY options and MUST BE presented as
206         the exact text of "none".
207
208       The arguments to either the command  line  option  or  the  environment
209       variable are in the form:
210
211       <tcti-name>:<tcti-option-config>
212
213       Specifying  an  empty  string  for  either the <tcti-name> or <tcti-op‐
214       tion-config> results in the default being used for that portion respec‐
215       tively.
216
217   TCTI Defaults
218       When  a  TCTI  is not specified, the default TCTI is searched for using
219       dlopen(3) semantics.  The tools will  search  for  tabrmd,  device  and
220       mssim  TCTIs  IN THAT ORDER and USE THE FIRST ONE FOUND.  You can query
221       what TCTI will be chosen as the default by using the -v option to print
222       the  version information.  The "default-tcti" key-value pair will indi‐
223       cate which of the aforementioned TCTIs is the default.
224
225   Custom TCTIs
226       Any TCTI that implements the dynamic TCTI interface can be loaded.  The
227       tools internally use dlopen(3), and the raw tcti-name value is used for
228       the lookup.  Thus, this could be a path to the shared library, or a li‐
229       brary name as understood by dlopen(3) semantics.
230

TCTI OPTIONS

232       This collection of options are used to configure the various known TCTI
233       modules available:
234
235       · device: For the device TCTI, the TPM character device file for use by
236         the device TCTI can be specified.  The default is /dev/tpm0.
237
238         Example:    -T   device:/dev/tpm0   or   export   TPM2TOOLS_TCTI="de‐
239         vice:/dev/tpm0"
240
241       · mssim: For the mssim TCTI, the domain name or  IP  address  and  port
242         number  used  by  the  simulator  can  be specified.  The default are
243         127.0.0.1 and 2321.
244
245         Example: -T mssim:host=localhost,port=2321  or  export  TPM2TOOLS_TC‐
246         TI="mssim:host=localhost,port=2321"
247
248       · abrmd:  For  the abrmd TCTI, the configuration string format is a se‐
249         ries of simple key value pairs separated by a  ','  character.   Each
250         key and value string are separated by a '=' character.
251
252         · TCTI abrmd supports two keys:
253
254           1. 'bus_name'  :  The  name  of  the  tabrmd  service on the bus (a
255              string).
256
257           2. 'bus_type' : The type of the dbus instance (a string) limited to
258              'session' and 'system'.
259
260         Specify  the tabrmd tcti name and a config string of bus_name=com.ex‐
261         ample.FooBar:
262
263         \--tcti=tabrmd:bus_name=com.example.FooBar
264
265         Specify the default (abrmd) tcti and a config string of bus_type=ses‐
266         sion:
267
268         \--tcti:bus_type=session
269
270         NOTE:  abrmd  and tabrmd are synonymous.  the various known TCTI mod‐
271         ules.
272

EXAMPLES

274              echo "secretdata" > secret.data
275
276              tpm2_unseal -c item.context -p abc123 -o out.dat
277
278              tpm2_unseal -c 0x81010001 -p "hex:123abc" -o out.dat
279
280              tpm2_unseal -c item.context -p pcr:sha256:0,1=pcr.value -o out.dat
281

Returns

283       Tools can return any of the following codes:
284
285       · 0 - Success.
286
287       · 1 - General non-specific error.
288
289       · 2 - Options handling error.
290
291       · 3 - Authentication error.
292
293       · 4 - TCTI related error.
294
295       · 5 - Non supported scheme.  Applicable to tpm2_testparams.
296

BUGS

298       Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
299

HELP

301       See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)
302
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305tpm2-tools                                                      tpm2_unseal(1)
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