1tpm2_getsessionauditdigest(1)General Commands Manuatlpm2_getsessionauditdigest(1)
2
6 tpm2_getsessionauditdigest(1) - Retrieve the command audit attestation
7 data from the TPM.
8
10 tpm2_getsessionauditdigest [OPTIONS]
11
13 tpm2_getsessionauditdigest(1) - Retrieve the session audit digest at‐
14 testation data from the TPM. The attestation data includes the session
15 audit digest and a signature over the session audit digest. The ses‐
16 sion itself is started with the tpm2_startauthsession command.
17
19 • -P, --hierarchy-auth=AUTH:
20 Specifies the authorization value for the endorsement hierarchy.
22 • -c, --key-context=OBJECT:
24 Context object for the signing key that signs the attestation data.
26 • -p, --auth=AUTH:
28 Specifies the authorization value for key specified by option -c.
30 • -q, --qualification=HEX_STRING_OR_PATH:
32 Data given as a Hex string or binary file to qualify the quote, op‐
34 tional. This is typically used to add a nonce against replay at‐
35 tacks.
36 • -s, --signature=FILE:
38 Signature output file, records the signature in the format specified
40 via the -f option.
41 • -m, --message=FILE:
43 Message output file, records the quote message that makes up the data
45 that is signed by the TPM. This is the command audit digest attesta‐
46 tion data.
47 • -f, --format=FORMAT:
49 Format selection for the signature output file.
51 • -g, --hash-algorithm:
53 Hash algorithm for signature. Defaults to sha256.
55 • --scheme=ALGORITHM:
57 The signing scheme used to sign the message. Optional. Signing
59 schemes should follow the “formatting standards”, see section “Algo‐
60 rithm Specifiers”. Also, see section “Supported Signing Schemes” for
61 a list of supported signature schemes. If specified, the signature
62 scheme must match the key type. If left unspecified, a default sig‐
63 nature scheme for the key type will be used.
64 • -S, --session=FILE:
66 The path of the session that enables and records the audit digests.
68 References
71 The type of a context object, whether it is a handle or file name, is
72 determined according to the following logic in-order:
73 • If the argument is a file path, then the file is loaded as a restored
75 TPM transient object.
76 • If the argument is a prefix match on one of:
78 • owner: the owner hierarchy
80 • platform: the platform hierarchy
82 • endorsement: the endorsement hierarchy
84 • lockout: the lockout control persistent object
86 • If the argument argument can be loaded as a number it will be treat
88 as a handle, e.g. 0x81010013 and used directly._OBJECT_.
89
91 Authorization for use of an object in TPM2.0 can come in 3 different
92 forms: 1. Password 2. HMAC 3. Sessions
93 NOTE: “Authorizations default to the EMPTY PASSWORD when not speci‐
95 fied”.
96 Passwords
98 Passwords are interpreted in the following forms below using prefix
99 identifiers.
100 Note: By default passwords are assumed to be in the string form when
102 they do not have a prefix.
103 String
105 A string password, specified by prefix “str:” or it’s absence (raw
106 string without prefix) is not interpreted, and is directly used for au‐
107 thorization.
108 Examples
110 foobar
111 str:foobar
112 Hex-string
114 A hex-string password, specified by prefix “hex:” is converted from a
115 hexidecimal form into a byte array form, thus allowing passwords with
116 non-printable and/or terminal un-friendly characters.
117 Example
119 hex:1122334455667788
120 File
122 A file based password, specified be prefix “file:” should be the path
123 of a file containing the password to be read by the tool or a “-” to
124 use stdin. Storing passwords in files prevents information leakage,
125 passwords passed as options can be read from the process list or common
126 shell history features.
127 Examples
129 # to use stdin and be prompted
130 file:-
131 # to use a file from a path
133 file:path/to/password/file
134 # to echo a password via stdin:
136 echo foobar | tpm2_tool -p file:-
137 # to use a bash here-string via stdin:
139 tpm2_tool -p file:- <<< foobar
141 Sessions
143 When using a policy session to authorize the use of an object, prefix
144 the option argument with the session keyword. Then indicate a path to
145 a session file that was created with tpm2_startauthsession(1). Option‐
146 ally, if the session requires an auth value to be sent with the session
147 handle (eg policy password), then append a + and a string as described
148 in the Passwords section.
149 Examples
151 To use a session context file called session.ctx.
152 session:session.ctx
154 To use a session context file called session.ctx AND send the authvalue
156 mypassword.
157 session:session.ctx+mypassword
159 To use a session context file called session.ctx AND send the HEX auth‐
161 value 0x11223344.
162 session:session.ctx+hex:11223344
164 PCR Authorizations
166 You can satisfy a PCR policy using the “pcr:” prefix and the PCR mini‐
167 language. The PCR minilanguage is as follows:
168 <pcr-spec>=<raw-pcr-file>
169 The PCR spec is documented in in the section “PCR bank specifiers”.
171 The raw-pcr-file is an optional argument that contains the output of
173 the raw PCR contents as returned by tpm2_pcrread(1).
174 PCR bank specifiers (pcr.md)
176 Examples
178 To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifi‐
179 er of:
180 pcr:sha256:0,1,2,3
182 specifying AUTH.
184
186 Format selection for the signature output file. tss (the default) will
187 output a binary blob according to the TPM 2.0 specification and any po‐
188 tential compiler padding. The option plain will output the plain sig‐
189 nature data as defined by the used cryptographic algorithm. signature
190 FORMAT.
191
193 This collection of options are common to many programs and provide in‐
194 formation that many users may expect.
195 • -h, --help=[man|no-man]: Display the tools manpage. By default, it
197 attempts to invoke the manpager for the tool, however, on failure
198 will output a short tool summary. This is the same behavior if the
199 “man” option argument is specified, however if explicit “man” is re‐
200 quested, the tool will provide errors from man on stderr. If the
201 “no-man” option if specified, or the manpager fails, the short op‐
202 tions will be output to stdout.
203 To successfully use the manpages feature requires the manpages to be
205 installed or on MANPATH, See man(1) for more details.
206 • -v, --version: Display version information for this tool, supported
208 tctis and exit.
209 • -V, --verbose: Increase the information that the tool prints to the
211 console during its execution. When using this option the file and
212 line number are printed.
213 • -Q, --quiet: Silence normal tool output to stdout.
215 • -Z, --enable-errata: Enable the application of errata fixups. Useful
217 if an errata fixup needs to be applied to commands sent to the TPM.
218 Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent. in‐
219 formation many users may expect.
220
222 The TCTI or “Transmission Interface” is the communication mechanism
223 with the TPM. TCTIs can be changed for communication with TPMs across
224 different mediums.
225 To control the TCTI, the tools respect:
227 1. The command line option -T or --tcti
229 2. The environment variable: TPM2TOOLS_TCTI.
231 Note: The command line option always overrides the environment vari‐
233 able.
234 The current known TCTIs are:
236 • tabrmd - The resource manager, called tabrmd
238 (https://github.com/tpm2-software/tpm2-abrmd). Note that tabrmd and
239 abrmd as a tcti name are synonymous.
240 • mssim - Typically used for communicating to the TPM software simula‐
242 tor.
243 • device - Used when talking directly to a TPM device file.
245 • none - Do not initalize a connection with the TPM. Some tools allow
247 for off-tpm options and thus support not using a TCTI. Tools that do
248 not support it will error when attempted to be used without a TCTI
249 connection. Does not support ANY options and MUST BE presented as
250 the exact text of “none”.
251 The arguments to either the command line option or the environment
253 variable are in the form:
254 <tcti-name>:<tcti-option-config>
256 Specifying an empty string for either the <tcti-name> or <tcti-op‐
258 tion-config> results in the default being used for that portion respec‐
259 tively.
260 TCTI Defaults
262 When a TCTI is not specified, the default TCTI is searched for using
263 dlopen(3) semantics. The tools will search for tabrmd, device and
264 mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND. You can query
265 what TCTI will be chosen as the default by using the -v option to print
266 the version information. The “default-tcti” key-value pair will indi‐
267 cate which of the aforementioned TCTIs is the default.
268 Custom TCTIs
270 Any TCTI that implements the dynamic TCTI interface can be loaded. The
271 tools internally use dlopen(3), and the raw tcti-name value is used for
272 the lookup. Thus, this could be a path to the shared library, or a li‐
273 brary name as understood by dlopen(3) semantics.
274
276 This collection of options are used to configure the various known TCTI
277 modules available:
278 • device: For the device TCTI, the TPM character device file for use by
280 the device TCTI can be specified. The default is /dev/tpm0.
281 Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI=“de‐
283 vice:/dev/tpm0”
284 • mssim: For the mssim TCTI, the domain name or IP address and port
286 number used by the simulator can be specified. The default are
287 127.0.0.1 and 2321.
288 Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TC‐
290 TI=“mssim:host=localhost,port=2321”
291 • abrmd: For the abrmd TCTI, the configuration string format is a se‐
293 ries of simple key value pairs separated by a `,' character. Each
294 key and value string are separated by a `=' character.
295 • TCTI abrmd supports two keys:
297 1. `bus_name' : The name of the tabrmd service on the bus (a
299 string).
300 2. `bus_type' : The type of the dbus instance (a string) limited to
302 `session' and `system'.
303 Specify the tabrmd tcti name and a config string of bus_name=com.ex‐
305 ample.FooBar:
306 \--tcti=tabrmd:bus_name=com.example.FooBar
308 Specify the default (abrmd) tcti and a config string of bus_type=ses‐
310 sion:
311 \--tcti:bus_type=session
313 NOTE: abrmd and tabrmd are synonymous. the various known TCTI mod‐
315 ules.
316
318 tpm2_createprimary -Q -C e -c prim.ctx
319 tpm2_create -Q -C prim.ctx -c signing_key.ctx -u signing_key.pub \
321 -r signing_key.priv
322 tpm2_startauthsession -S session.ctx --audit-session
324 tpm2_getrandom 8 -S session.ctx
326 tpm2_getsessionauditdigest -c signing_key.ctx -m att.data -s att.sig \
328 -S session.ctx
329
331 Tools can return any of the following codes:
332 • 0 - Success.
334 • 1 - General non-specific error.
336 • 2 - Options handling error.
338 • 3 - Authentication error.
340 • 4 - TCTI related error.
342 • 5 - Non supported scheme. Applicable to tpm2_testparams.
344
346 Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
347
349 See the Mailing List (https://lists.linuxfoundation.org/mailman/listin‐
350 fo/tpm2)
351tpm2-tools tpm2_getsessionauditdigest(1)