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, it
37 simply returns a cpHash, unless rphash is also required.
38 • --rphash=FILE
40 File path to record the hash of the response parameters. This is
42 commonly termed as rpHash.
43 • -S, --session=FILE:
45 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 References
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 • If the argument is a file path, then the file is loaded as a restored
56 TPM transient object.
57 • If the argument is a prefix match on one of:
59 • owner: the owner hierarchy
61 • platform: the platform hierarchy
63 • endorsement: the endorsement hierarchy
65 • lockout: the lockout control persistent object
67 • 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
72 Authorization for use of an object in TPM2.0 can come in 3 different
73 forms: 1. Password 2. HMAC 3. Sessions
74 NOTE: “Authorizations default to the EMPTY PASSWORD when not speci‐
76 fied”.
77 Passwords
79 Passwords are interpreted in the following forms below using prefix
80 identifiers.
81 Note: By default passwords are assumed to be in the string form when
83 they do not have a prefix.
84 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 Examples
91 foobar
92 str:foobar
93 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 Example
100 hex:1122334455667788
101 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 Examples
110 # to use stdin and be prompted
111 file:-
112 # to use a file from a path
114 file:path/to/password/file
115 # to echo a password via stdin:
117 echo foobar | tpm2_tool -p file:-
118 # to use a bash here-string via stdin:
120 tpm2_tool -p file:- <<< foobar
122 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 Examples
132 To use a session context file called session.ctx.
133 session:session.ctx
135 To use a session context file called session.ctx AND send the authvalue
137 mypassword.
138 session:session.ctx+mypassword
140 To use a session context file called session.ctx AND send the HEX auth‐
142 value 0x11223344.
143 session:session.ctx+hex:11223344
145 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 The PCR spec is documented in in the section “PCR bank specifiers”.
152 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 PCR bank specifiers (pcr.md)
157 Examples
159 To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifi‐
160 er of:
161 pcr:sha256:0,1,2,3
163 specifying AUTH.
165
167 This collection of options are common to many programs and provide in‐
168 formation that many users may expect.
169 • -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 To successfully use the manpages feature requires the manpages to be
179 installed or on MANPATH, See man(1) for more details.
180 • -v, --version: Display version information for this tool, supported
182 tctis and exit.
183 • -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 • -Q, --quiet: Silence normal tool output to stdout.
189 • -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
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 To control the TCTI, the tools respect:
201 1. The command line option -T or --tcti
203 2. The environment variable: TPM2TOOLS_TCTI.
205 Note: The command line option always overrides the environment vari‐
207 able.
208 The current known TCTIs are:
210 • 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 • mssim - Typically used for communicating to the TPM software simula‐
216 tor.
217 • device - Used when talking directly to a TPM device file.
219 • 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 The arguments to either the command line option or the environment
227 variable are in the form:
228 <tcti-name>:<tcti-option-config>
230 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 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 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
250 This collection of options are used to configure the various known TCTI
251 modules available:
252 • device: 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 Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI=“de‐
257 vice:/dev/tpm0”
258 • mssim: 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 Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TC‐
264 TI=“mssim:host=localhost,port=2321”
265 • abrmd: 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 • TCTI abrmd supports two keys:
271 1. `bus_name' : The name of the tabrmd service on the bus (a
273 string).
274 2. `bus_type' : The type of the dbus instance (a string) limited to
276 `session' and `system'.
277 Specify the tabrmd tcti name and a config string of bus_name=com.ex‐
279 ample.FooBar:
280 \--tcti=tabrmd:bus_name=com.example.FooBar
282 Specify the default (abrmd) tcti and a config string of bus_type=ses‐
284 sion:
285 \--tcti:bus_type=session
287 NOTE: abrmd and tabrmd are synonymous. the various known TCTI mod‐
289 ules.
290
292 tpm2_createprimary -c primary.ctx -Q
293 tpm2_pcrread -Q -o pcr.bin sha256:0,1,2,3
295 tpm2_createpolicy -Q --policy-pcr -l sha256:0,1,2,3 -f pcr.bin -L pcr.policy
297 echo 'secret' | tpm2_create -C primary.ctx -L pcr.policy -i-\
299 -u seal.pub -r seal.priv -c seal.ctx -Q
300 tpm2_unseal -c seal.ctx -p pcr:sha256:0,1,2,3
302
304 Tools can return any of the following codes:
305 • 0 - Success.
307 • 1 - General non-specific error.
309 • 2 - Options handling error.
311 • 3 - Authentication error.
313 • 4 - TCTI related error.
315 • 5 - Non supported scheme. Applicable to tpm2_testparams.
317
319 Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
320
322 See the Mailing List (https://lists.linuxfoundation.org/mailman/listin‐
323 fo/tpm2)
324tpm2-tools tpm2_unseal(1)