1tpm2_policysigned(1) General Commands Manual tpm2_policysigned(1)
2
6 tpm2_policysigned(1) - Enables policy authorization by verifying signa‐
7 ture of optional TPM2 parameters. The signature is generated by a
8 signing authority.
9
11 tpm2_policysigned [OPTIONS]
12
14 tpm2_policysigned(1) - Enables policy authorization by verifying signa‐
15 ture of optional TPM2 parameters. The signature is generated by a
16 signing authority. The optional TPM2 parameters being cpHashA, non‐
17 ceTPM, policyRef and expiration.
18
20 • -L, --policy=FILE:
21 File to save the compounded policy digest.
23 • -S, --session=FILE:
25 The policy session file generated via the -S option to tpm2_star‐
27 tauthsession(1).
28 • -c, --key-context=OBJECT:
30 Context object for the key context used for the operation. Either a
32 file or a handle number. See section “Context Object Format”.
33 • -g, --hash-algorithm=ALGORITHM:
35 The hash algorithm used to digest the message.
37 • -s, --signature=FILE:
39 The input signature file of the signature to be validated.
41 • -f, --format=FORMAT:
43 Set the input signature file to a specified format. The default is
45 the tpm2.0 TPMT_SIGNATURE data format, however different schemes can
46 be selected if the data came from an external source like OpenSSL.
47 The tool currently supports rsassa and ecdsa.
48 • -t, --expiration=NATURAL_NUMBER:
50 Set the expiration time of the policy in seconds. In absence of non‐
52 ceTPM the expiration time is the policy timeout value. If expiration
53 is a negative value an authorization ticket is additionally returned.
54 If expiration value is 0 then the policy does not have a time limit
55 on the authorization.
56 • --cphash-input=FILE:
58 The command parameter hash (cpHash), enforcing the TPM command to be
60 authorized as well as its handle and parameter values.
61 • --ticket=FILE:
63 The ticket file to record the authorization ticket structure.
65 • --timeout=FILE:
67 The file path to record the timeout structure returned.
69 • -q, --qualification=FILE_OR_HEX_STR:
71 Optional, the policy qualifier data that the signer can choose to in‐
73 clude in the signature. Can be either a hex string or path.
74 • -x, --nonce-tpm:
76 Enable the comparison of the current session’s nonceTPM to ensure the
78 validity of the policy authorization is limited to the current ses‐
79 sion.
80 References
83 This collection of options are common to many programs and provide in‐
84 formation that many users may expect.
85 • -h, --help=[man|no-man]: Display the tools manpage. By default, it
87 attempts to invoke the manpager for the tool, however, on failure
88 will output a short tool summary. This is the same behavior if the
89 “man” option argument is specified, however if explicit “man” is re‐
90 quested, the tool will provide errors from man on stderr. If the
91 “no-man” option if specified, or the manpager fails, the short op‐
92 tions will be output to stdout.
93 To successfully use the manpages feature requires the manpages to be
95 installed or on MANPATH, See man(1) for more details.
96 • -v, --version: Display version information for this tool, supported
98 tctis and exit.
99 • -V, --verbose: Increase the information that the tool prints to the
101 console during its execution. When using this option the file and
102 line number are printed.
103 • -Q, --quiet: Silence normal tool output to stdout.
105 • -Z, --enable-errata: Enable the application of errata fixups. Useful
107 if an errata fixup needs to be applied to commands sent to the TPM.
108 Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent. in‐
109 formation many users may expect.
110
112 The TCTI or “Transmission Interface” is the communication mechanism
113 with the TPM. TCTIs can be changed for communication with TPMs across
114 different mediums.
115 To control the TCTI, the tools respect:
117 1. The command line option -T or --tcti
119 2. The environment variable: TPM2TOOLS_TCTI.
121 Note: The command line option always overrides the environment vari‐
123 able.
124 The current known TCTIs are:
126 • tabrmd - The resource manager, called tabrmd
128 (https://github.com/tpm2-software/tpm2-abrmd). Note that tabrmd and
129 abrmd as a tcti name are synonymous.
130 • mssim - Typically used for communicating to the TPM software simula‐
132 tor.
133 • device - Used when talking directly to a TPM device file.
135 • none - Do not initalize a connection with the TPM. Some tools allow
137 for off-tpm options and thus support not using a TCTI. Tools that do
138 not support it will error when attempted to be used without a TCTI
139 connection. Does not support ANY options and MUST BE presented as
140 the exact text of “none”.
141 The arguments to either the command line option or the environment
143 variable are in the form:
144 <tcti-name>:<tcti-option-config>
146 Specifying an empty string for either the <tcti-name> or <tcti-op‐
148 tion-config> results in the default being used for that portion respec‐
149 tively.
150 TCTI Defaults
152 When a TCTI is not specified, the default TCTI is searched for using
153 dlopen(3) semantics. The tools will search for tabrmd, device and
154 mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND. You can query
155 what TCTI will be chosen as the default by using the -v option to print
156 the version information. The “default-tcti” key-value pair will indi‐
157 cate which of the aforementioned TCTIs is the default.
158 Custom TCTIs
160 Any TCTI that implements the dynamic TCTI interface can be loaded. The
161 tools internally use dlopen(3), and the raw tcti-name value is used for
162 the lookup. Thus, this could be a path to the shared library, or a li‐
163 brary name as understood by dlopen(3) semantics.
164
166 This collection of options are used to configure the various known TCTI
167 modules available:
168 • device: For the device TCTI, the TPM character device file for use by
170 the device TCTI can be specified. The default is /dev/tpm0.
171 Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI=“de‐
173 vice:/dev/tpm0”
174 • mssim: For the mssim TCTI, the domain name or IP address and port
176 number used by the simulator can be specified. The default are
177 127.0.0.1 and 2321.
178 Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TC‐
180 TI=“mssim:host=localhost,port=2321”
181 • abrmd: For the abrmd TCTI, the configuration string format is a se‐
183 ries of simple key value pairs separated by a `,' character. Each
184 key and value string are separated by a `=' character.
185 • TCTI abrmd supports two keys:
187 1. `bus_name' : The name of the tabrmd service on the bus (a
189 string).
190 2. `bus_type' : The type of the dbus instance (a string) limited to
192 `session' and `system'.
193 Specify the tabrmd tcti name and a config string of bus_name=com.ex‐
195 ample.FooBar:
196 \--tcti=tabrmd:bus_name=com.example.FooBar
198 Specify the default (abrmd) tcti and a config string of bus_type=ses‐
200 sion:
201 \--tcti:bus_type=session
203 NOTE: abrmd and tabrmd are synonymous. the various known TCTI mod‐
205 ules.
206
208 Authorize a TPM operation on an object whose authorization is bound to
209 specific signing authority.
210 Create the signing authority
212 openssl genrsa -out private.pem 2048
213 openssl rsa -in private.pem -outform PEM -pubout -out public.pem
215 Generate signature with nonceTPM, cpHashA, policyRef and expiration set to
217 0
218 echo "00 00 00 00" | xxd -r -p | \
219 openssl dgst -sha256 -sign private.pem -out signature.dat
220 Load the verification key and Create the policysigned policy
222 tpm2_loadexternal -C o -G rsa -u public.pem -c signing_key.ctx
223 tpm2_startauthsession -S session.ctx
225 tpm2_policysigned -S session.ctx -g sha256 -s signature.dat -f rsassa \
227 -c signing_key.ctx -L policy.signed
228 tpm2_flushcontext session.ctx
230 Create a sealing object to use the policysigned
232 echo "plaintext" > secret.data
233 tpm2_createprimary -C o -c prim.ctx
235 tpm2_create -u key.pub -r sealing_key.priv -c sealing_key.ctx -C prim.ctx \
237 -i secret.data -L policy.signed
238 Satisfy the policy and unseal secret
240 tpm2_startauthsession -S session.ctx --policy-session
241 tpm2_policysigned -S session.ctx -g sha256 -s signature.dat -f rsassa \
243 -c signing_key.ctx -L policy.signed
244 tpm2_unseal -p session:session.ctx -c sealing_key.ctx
246 tpm2_flushcontext session.ctx
248
250 Tools can return any of the following codes:
251 • 0 - Success.
253 • 1 - General non-specific error.
255 • 2 - Options handling error.
257 • 3 - Authentication error.
259 • 4 - TCTI related error.
261 • 5 - Non supported scheme. Applicable to tpm2_testparams.
263
265 It expects a session to be already established via tpm2_startauthses‐
266 sion(1) and requires one of the following:
267 • direct device access
269 • extended session support with tpm2-abrmd.
271 Without it, most resource managers will not save session state between
273 command invocations.
274
276 Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
277
279 See the Mailing List (https://lists.linuxfoundation.org/mailman/listin‐
280 fo/tpm2)
281tpm2-tools tpm2_policysigned(1)