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 · --cphash=FILE
33 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.
37 References
40 The type of a context object, whether it is a handle or file name, is
41 determined according to the following logic in-order:
42 · If the argument is a file path, then the file is loaded as a restored
44 TPM transient object.
45 · If the argument is a prefix match on one of:
47 · owner: the owner hierarchy
49 · platform: the platform hierarchy
51 · endorsement: the endorsement hierarchy
53 · lockout: the lockout control persistent object
55 · If the argument argument can be loaded as a number it will be treat
57 as a handle, e.g. 0x81010013 and used directly.OBJECT.
58
60 Authorization for use of an object in TPM2.0 can come in 3 different
61 forms: 1. Password 2. HMAC 3. Sessions
62 NOTE: "Authorizations default to the EMPTY PASSWORD when not speci‐
64 fied".
65 Passwords
67 Passwords are interpreted in the following forms below using prefix
68 identifiers.
69 Note: By default passwords are assumed to be in the string form when
71 they do not have a prefix.
72 String
74 A string password, specified by prefix "str:" or it's absence (raw
75 string without prefix) is not interpreted, and is directly used for au‐
76 thorization.
77 Examples
79 foobar
80 str:foobar
81 Hex-string
83 A hex-string password, specified by prefix "hex:" is converted from a
84 hexidecimal form into a byte array form, thus allowing passwords with
85 non-printable and/or terminal un-friendly characters.
86 Example
88 hex:0x1122334455667788
89 File
91 A file based password, specified be prefix "file:" should be the path
92 of a file containing the password to be read by the tool or a "-" to
93 use stdin. Storing passwords in files prevents information leakage,
94 passwords passed as options can be read from the process list or common
95 shell history features.
96 Examples
98 # to use stdin and be prompted
99 file:-
100 # to use a file from a path
102 file:path/to/password/file
103 # to echo a password via stdin:
105 echo foobar | tpm2_tool -p file:-
106 # to use a bash here-string via stdin:
108 tpm2_tool -p file:- <<< foobar
110 Sessions
112 When using a policy session to authorize the use of an object, prefix
113 the option argument with the session keyword. Then indicate a path to
114 a session file that was created with tpm2_startauthsession(1). Option‐
115 ally, if the session requires an auth value to be sent with the session
116 handle (eg policy password), then append a + and a string as described
117 in the Passwords section.
118 Examples
120 To use a session context file called session.ctx.
121 session:session.ctx
123 To use a session context file called session.ctx AND send the authvalue
125 mypassword.
126 session:session.ctx+mypassword
128 To use a session context file called session.ctx AND send the HEX auth‐
130 value 0x11223344.
131 session:session.ctx+hex:11223344
133 PCR Authorizations
135 You can satisfy a PCR policy using the "pcr:" prefix and the PCR mini‐
136 language. The PCR minilanguage is as follows:
137 <pcr-spec>=<raw-pcr-file>
138 The PCR spec is documented in in the section "PCR bank specifiers".
140 The raw-pcr-file is an optional the output of the raw PCR contents as
142 returned by tpm2_pcrread(1).
143 PCR bank specifiers (common/pcr.md)
145 Examples
147 To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifi‐
148 er of:
149 pcr:sha256:0,1,2,3
151 specifying AUTH.
153
155 This collection of options are common to many programs and provide in‐
156 formation that many users may expect.
157 · -h, --help=[man|no-man]: Display the tools manpage. By default, it
159 attempts to invoke the manpager for the tool, however, on failure
160 will output a short tool summary. This is the same behavior if the
161 "man" option argument is specified, however if explicit "man" is re‐
162 quested, the tool will provide errors from man on stderr. If the
163 "no-man" option if specified, or the manpager fails, the short op‐
164 tions will be output to stdout.
165 To successfully use the manpages feature requires the manpages to be
167 installed or on MANPATH, See man(1) for more details.
168 · -v, --version: Display version information for this tool, supported
170 tctis and exit.
171 · -V, --verbose: Increase the information that the tool prints to the
173 console during its execution. When using this option the file and
174 line number are printed.
175 · -Q, --quiet: Silence normal tool output to stdout.
177 · -Z, --enable-errata: Enable the application of errata fixups. Useful
179 if an errata fixup needs to be applied to commands sent to the TPM.
180 Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent. in‐
181 formation many users may expect.
182
184 The TCTI or "Transmission Interface" is the communication mechanism
185 with the TPM. TCTIs can be changed for communication with TPMs across
186 different mediums.
187 To control the TCTI, the tools respect:
189 1. The command line option -T or --tcti
191 2. The environment variable: TPM2TOOLS_TCTI.
193 Note: The command line option always overrides the environment vari‐
195 able.
196 The current known TCTIs are:
198 · tabrmd - The resource manager, called tabrmd
200 (https://github.com/tpm2-software/tpm2-abrmd). Note that tabrmd and
201 abrmd as a tcti name are synonymous.
202 · mssim - Typically used for communicating to the TPM software simula‐
204 tor.
205 · device - Used when talking directly to a TPM device file.
207 · none - Do not initalize a connection with the TPM. Some tools allow
209 for off-tpm options and thus support not using a TCTI. Tools that do
210 not support it will error when attempted to be used without a TCTI
211 connection. Does not support ANY options and MUST BE presented as
212 the exact text of "none".
213 The arguments to either the command line option or the environment
215 variable are in the form:
216 <tcti-name>:<tcti-option-config>
218 Specifying an empty string for either the <tcti-name> or <tcti-op‐
220 tion-config> results in the default being used for that portion respec‐
221 tively.
222 TCTI Defaults
224 When a TCTI is not specified, the default TCTI is searched for using
225 dlopen(3) semantics. The tools will search for tabrmd, device and
226 mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND. You can query
227 what TCTI will be chosen as the default by using the -v option to print
228 the version information. The "default-tcti" key-value pair will indi‐
229 cate which of the aforementioned TCTIs is the default.
230 Custom TCTIs
232 Any TCTI that implements the dynamic TCTI interface can be loaded. The
233 tools internally use dlopen(3), and the raw tcti-name value is used for
234 the lookup. Thus, this could be a path to the shared library, or a li‐
235 brary name as understood by dlopen(3) semantics.
236
238 This collection of options are used to configure the various known TCTI
239 modules available:
240 · device: For the device TCTI, the TPM character device file for use by
242 the device TCTI can be specified. The default is /dev/tpm0.
243 Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI="de‐
245 vice:/dev/tpm0"
246 · mssim: For the mssim TCTI, the domain name or IP address and port
248 number used by the simulator can be specified. The default are
249 127.0.0.1 and 2321.
250 Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TC‐
252 TI="mssim:host=localhost,port=2321"
253 · abrmd: For the abrmd TCTI, the configuration string format is a se‐
255 ries of simple key value pairs separated by a ',' character. Each
256 key and value string are separated by a '=' character.
257 · TCTI abrmd supports two keys:
259 1. 'bus_name' : The name of the tabrmd service on the bus (a
261 string).
262 2. 'bus_type' : The type of the dbus instance (a string) limited to
264 'session' and 'system'.
265 Specify the tabrmd tcti name and a config string of bus_name=com.ex‐
267 ample.FooBar:
268 \--tcti=tabrmd:bus_name=com.example.FooBar
270 Specify the default (abrmd) tcti and a config string of bus_type=ses‐
272 sion:
273 \--tcti:bus_type=session
275 NOTE: abrmd and tabrmd are synonymous. the various known TCTI mod‐
277 ules.
278
280 echo "secretdata" > secret.data
281 tpm2_unseal -c item.context -p abc123 -o out.dat
283 tpm2_unseal -c 0x81010001 -p "hex:123abc" -o out.dat
285 tpm2_unseal -c item.context -p pcr:sha256:0,1=pcr.value -o out.dat
287
289 Tools can return any of the following codes:
290 · 0 - Success.
292 · 1 - General non-specific error.
294 · 2 - Options handling error.
296 · 3 - Authentication error.
298 · 4 - TCTI related error.
300 · 5 - Non supported scheme. Applicable to tpm2_testparams.
302
304 Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
305
307 See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)
308tpm2-tools tpm2_unseal(1)