1tpm2_unseal(1) General Commands Manual tpm2_unseal(1)
2
6 tpm2_unseal(1) - Returns a data blob in a loaded TPM object. The data
7 blob is returned in clear.
8
10 tpm2_unseal [OPTIONS]
11
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
19 · -c, --object-context=OBJECT:
20 Object context for the loaded object.
22 · -p, --auth=AUTH:
24 Optional auth value to use for the key specified by -c.
26 · -o, --output=FILE:
28 Output file name containing the unsealed data. Defaults to STDOUT if
30 not specified.
31 References
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 · If the argument is a file path, then the file is loaded as a restored
38 TPM transient object.
39 · If the argument is a prefix match on one of:
41 · owner: the owner hierarchy
43 · platform: the platform hierarchy
45 · endorsement: the endorsement hierarchy
47 · lockout: the lockout control persistent object
49 · 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
54 Authorization for use of an object in TPM2.0 can come in 3 different
55 forms: 1. Password 2. HMAC 3. Sessions
56 NOTE: "Authorizations default to the EMPTY PASSWORD when not speci‐
58 fied".
59 Passwords
61 Passwords are interpreted in the following forms below using prefix
62 identifiers.
63 Note: By default passwords are assumed to be in the string form when
65 they do not have a prefix.
66 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 Examples
73 foobar
74 str:foobar
75 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 Example
82 hex:0x1122334455667788
83 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 Examples
92 # to use stdin and be prompted
93 file:-
94 # to use a file from a path
96 file:path/to/password/file
97 # to echo a password via stdin:
99 echo foobar | tpm2_tool -p file:-
100 # to use a bash here-string via stdin:
102 tpm2_tool -p file:- <<< foobar
104 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 Examples
114 To use a session context file called session.ctx.
115 session:session.ctx
117 To use a session context file called session.ctx AND send the authvalue
119 mypassword.
120 session:session.ctx+mypassword
122 To use a session context file called session.ctx AND send the HEX auth‐
124 value 0x11223344.
125 session:session.ctx+hex:11223344
127 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 The PCR spec is documented in in the section "PCR bank specifiers".
134 The raw-pcr-file is an optional the output of the raw PCR contents as
136 returned by tpm2_pcrread(1).
137 PCR bank specifiers (common/pcr.md)
139 Examples
141 To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifi‐
142 er of:
143 pcr:sha256:0,1,2,3
145 specifying AUTH.
147
149 This collection of options are common to many programs and provide in‐
150 formation that many users may expect.
151 · -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 To successfully use the manpages feature requires the manpages to be
161 installed or on MANPATH, See man(1) for more details.
162 · -v, --version: Display version information for this tool, supported
164 tctis and exit.
165 · -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 · -Q, --quiet: Silence normal tool output to stdout.
171 · -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
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 To control the TCTI, the tools respect:
183 1. The command line option -T or --tcti
185 2. The environment variable: TPM2TOOLS_TCTI.
187 Note: The command line option always overrides the environment vari‐
189 able.
190 The current known TCTIs are:
192 · 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 · mssim - Typically used for communicating to the TPM software simula‐
198 tor.
199 · device - Used when talking directly to a TPM device file.
201 · 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 The arguments to either the command line option or the environment
209 variable are in the form:
210 <tcti-name>:<tcti-option-config>
212 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 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 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
232 This collection of options are used to configure the various known TCTI
233 modules available:
234 · 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 Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI="de‐
239 vice:/dev/tpm0"
240 · 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 Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TC‐
246 TI="mssim:host=localhost,port=2321"
247 · 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 · TCTI abrmd supports two keys:
253 1. 'bus_name' : The name of the tabrmd service on the bus (a
255 string).
256 2. 'bus_type' : The type of the dbus instance (a string) limited to
258 'session' and 'system'.
259 Specify the tabrmd tcti name and a config string of bus_name=com.ex‐
261 ample.FooBar:
262 \--tcti=tabrmd:bus_name=com.example.FooBar
264 Specify the default (abrmd) tcti and a config string of bus_type=ses‐
266 sion:
267 \--tcti:bus_type=session
269 NOTE: abrmd and tabrmd are synonymous. the various known TCTI mod‐
271 ules.
272
274 echo "secretdata" > secret.data
275 tpm2_unseal -c item.context -p abc123 -o out.dat
277 tpm2_unseal -c 0x81010001 -p "hex:123abc" -o out.dat
279 tpm2_unseal -c item.context -p pcr:sha256:0,1=pcr.value -o out.dat
281
283 Tools can return any of the following codes:
284 · 0 - Success.
286 · 1 - General non-specific error.
288 · 2 - Options handling error.
290 · 3 - Authentication error.
292 · 4 - TCTI related error.
294 · 5 - Non supported scheme. Applicable to tpm2_testparams.
296
298 Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
299
301 See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)
302tpm2-tools tpm2_unseal(1)