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 • -S, --session=FILE:
57 The path of the session that enables and records the audit digests.
59 References
62 The type of a context object, whether it is a handle or file name, is
63 determined according to the following logic in-order:
64 • If the argument is a file path, then the file is loaded as a restored
66 TPM transient object.
67 • If the argument is a prefix match on one of:
69 • owner: the owner hierarchy
71 • platform: the platform hierarchy
73 • endorsement: the endorsement hierarchy
75 • lockout: the lockout control persistent object
77 • If the argument argument can be loaded as a number it will be treat
79 as a handle, e.g. 0x81010013 and used directly._OBJECT_.
80
82 Authorization for use of an object in TPM2.0 can come in 3 different
83 forms: 1. Password 2. HMAC 3. Sessions
84 NOTE: “Authorizations default to the EMPTY PASSWORD when not speci‐
86 fied”.
87 Passwords
89 Passwords are interpreted in the following forms below using prefix
90 identifiers.
91 Note: By default passwords are assumed to be in the string form when
93 they do not have a prefix.
94 String
96 A string password, specified by prefix “str:” or it’s absence (raw
97 string without prefix) is not interpreted, and is directly used for au‐
98 thorization.
99 Examples
101 foobar
102 str:foobar
103 Hex-string
105 A hex-string password, specified by prefix “hex:” is converted from a
106 hexidecimal form into a byte array form, thus allowing passwords with
107 non-printable and/or terminal un-friendly characters.
108 Example
110 hex:0x1122334455667788
111 File
113 A file based password, specified be prefix “file:” should be the path
114 of a file containing the password to be read by the tool or a “-” to
115 use stdin. Storing passwords in files prevents information leakage,
116 passwords passed as options can be read from the process list or common
117 shell history features.
118 Examples
120 # to use stdin and be prompted
121 file:-
122 # to use a file from a path
124 file:path/to/password/file
125 # to echo a password via stdin:
127 echo foobar | tpm2_tool -p file:-
128 # to use a bash here-string via stdin:
130 tpm2_tool -p file:- <<< foobar
132 Sessions
134 When using a policy session to authorize the use of an object, prefix
135 the option argument with the session keyword. Then indicate a path to
136 a session file that was created with tpm2_startauthsession(1). Option‐
137 ally, if the session requires an auth value to be sent with the session
138 handle (eg policy password), then append a + and a string as described
139 in the Passwords section.
140 Examples
142 To use a session context file called session.ctx.
143 session:session.ctx
145 To use a session context file called session.ctx AND send the authvalue
147 mypassword.
148 session:session.ctx+mypassword
150 To use a session context file called session.ctx AND send the HEX auth‐
152 value 0x11223344.
153 session:session.ctx+hex:11223344
155 PCR Authorizations
157 You can satisfy a PCR policy using the “pcr:” prefix and the PCR mini‐
158 language. The PCR minilanguage is as follows:
159 <pcr-spec>=<raw-pcr-file>
160 The PCR spec is documented in in the section “PCR bank specifiers”.
162 The raw-pcr-file is an optional argument that contains the output of
164 the raw PCR contents as returned by tpm2_pcrread(1).
165 PCR bank specifiers (pcr.md)
167 Examples
169 To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifi‐
170 er of:
171 pcr:sha256:0,1,2,3
173 specifying AUTH.
175
177 Format selection for the signature output file. tss (the default) will
178 output a binary blob according to the TPM 2.0 specification and any po‐
179 tential compiler padding. The option plain will output the plain sig‐
180 nature data as defined by the used cryptographic algorithm. signature
181 FORMAT.
182
184 This collection of options are common to many programs and provide in‐
185 formation that many users may expect.
186 • -h, --help=[man|no-man]: Display the tools manpage. By default, it
188 attempts to invoke the manpager for the tool, however, on failure
189 will output a short tool summary. This is the same behavior if the
190 “man” option argument is specified, however if explicit “man” is re‐
191 quested, the tool will provide errors from man on stderr. If the
192 “no-man” option if specified, or the manpager fails, the short op‐
193 tions will be output to stdout.
194 To successfully use the manpages feature requires the manpages to be
196 installed or on MANPATH, See man(1) for more details.
197 • -v, --version: Display version information for this tool, supported
199 tctis and exit.
200 • -V, --verbose: Increase the information that the tool prints to the
202 console during its execution. When using this option the file and
203 line number are printed.
204 • -Q, --quiet: Silence normal tool output to stdout.
206 • -Z, --enable-errata: Enable the application of errata fixups. Useful
208 if an errata fixup needs to be applied to commands sent to the TPM.
209 Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent. in‐
210 formation many users may expect.
211
213 The TCTI or “Transmission Interface” is the communication mechanism
214 with the TPM. TCTIs can be changed for communication with TPMs across
215 different mediums.
216 To control the TCTI, the tools respect:
218 1. The command line option -T or --tcti
220 2. The environment variable: TPM2TOOLS_TCTI.
222 Note: The command line option always overrides the environment vari‐
224 able.
225 The current known TCTIs are:
227 • tabrmd - The resource manager, called tabrmd
229 (https://github.com/tpm2-software/tpm2-abrmd). Note that tabrmd and
230 abrmd as a tcti name are synonymous.
231 • mssim - Typically used for communicating to the TPM software simula‐
233 tor.
234 • device - Used when talking directly to a TPM device file.
236 • none - Do not initalize a connection with the TPM. Some tools allow
238 for off-tpm options and thus support not using a TCTI. Tools that do
239 not support it will error when attempted to be used without a TCTI
240 connection. Does not support ANY options and MUST BE presented as
241 the exact text of “none”.
242 The arguments to either the command line option or the environment
244 variable are in the form:
245 <tcti-name>:<tcti-option-config>
247 Specifying an empty string for either the <tcti-name> or <tcti-op‐
249 tion-config> results in the default being used for that portion respec‐
250 tively.
251 TCTI Defaults
253 When a TCTI is not specified, the default TCTI is searched for using
254 dlopen(3) semantics. The tools will search for tabrmd, device and
255 mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND. You can query
256 what TCTI will be chosen as the default by using the -v option to print
257 the version information. The “default-tcti” key-value pair will indi‐
258 cate which of the aforementioned TCTIs is the default.
259 Custom TCTIs
261 Any TCTI that implements the dynamic TCTI interface can be loaded. The
262 tools internally use dlopen(3), and the raw tcti-name value is used for
263 the lookup. Thus, this could be a path to the shared library, or a li‐
264 brary name as understood by dlopen(3) semantics.
265
267 This collection of options are used to configure the various known TCTI
268 modules available:
269 • device: For the device TCTI, the TPM character device file for use by
271 the device TCTI can be specified. The default is /dev/tpm0.
272 Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI=“de‐
274 vice:/dev/tpm0”
275 • mssim: For the mssim TCTI, the domain name or IP address and port
277 number used by the simulator can be specified. The default are
278 127.0.0.1 and 2321.
279 Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TC‐
281 TI=“mssim:host=localhost,port=2321”
282 • abrmd: For the abrmd TCTI, the configuration string format is a se‐
284 ries of simple key value pairs separated by a `,' character. Each
285 key and value string are separated by a `=' character.
286 • TCTI abrmd supports two keys:
288 1. `bus_name' : The name of the tabrmd service on the bus (a
290 string).
291 2. `bus_type' : The type of the dbus instance (a string) limited to
293 `session' and `system'.
294 Specify the tabrmd tcti name and a config string of bus_name=com.ex‐
296 ample.FooBar:
297 \--tcti=tabrmd:bus_name=com.example.FooBar
299 Specify the default (abrmd) tcti and a config string of bus_type=ses‐
301 sion:
302 \--tcti:bus_type=session
304 NOTE: abrmd and tabrmd are synonymous. the various known TCTI mod‐
306 ules.
307
309 tpm2_createprimary -Q -C e -c prim.ctx
310 tpm2_create -Q -C prim.ctx -c signing_key.ctx -u signing_key.pub \
312 -r signing_key.priv
313 tpm2_startauthsession -S session.ctx --audit-session
315 tpm2_getrandom 8 -S session.ctx
317 tpm2_getsessionauditdigest -c signing_key.ctx -m att.data -s att.sig \
319 -S session.ctx
320
322 Tools can return any of the following codes:
323 • 0 - Success.
325 • 1 - General non-specific error.
327 • 2 - Options handling error.
329 • 3 - Authentication error.
331 • 4 - TCTI related error.
333 • 5 - Non supported scheme. Applicable to tpm2_testparams.
335
337 Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
338
340 See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)
341tpm2-tools tpm2_getsessionauditdigest(1)