1tpm2_changeauth(1)          General Commands Manual         tpm2_changeauth(1)
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NAME

6       tpm2_changeauth - Changes authorization values for TPM objects.
7

SYNOPSIS

9       tpm2_changeauth [OPTIONS] [ARGUMENT]
10

DESCRIPTION

12       tpm2_changeauth - Configures authorization values for the various hier‐
13       archies, NV indices, transient and persistent objects.
14
15       Note: For non-permanent objects (Transient objects and  Persistent  ob‐
16       jects), copies of the private information (files or persistent handles)
17       created prior to changing auth are not invalidated.
18

OPTIONS

20       Passwords should follow the "password  authorization  formatting  stan‐
21       dards", see section "Authorization Formatting".
22
23       · -c, --object-context=OBJECT:
24
25         The key context object to be used for the operation.
26
27       · -p, --object-auth=AUTH:
28
29         The old authorization value for the TPM object specified with -c.
30
31       · -C, --parent-context=OBJECT:
32
33         The  parent object.  This is required if the object for the operation
34         is a transient or persistent object.
35
36       · -r, --private=FILE: The output file which contains the new  sensitive
37         portion of the object whose auth was being changed.
38
39       · --cphash=FILE
40
41         File path to record the hash of the command parameters.  This is com‐
42         monly termed as cpHash.  NOTE: When this option is selected, The tool
43         will not actually execute the command, it simply returns a cpHash.
44
45       · ARGUMENT  the  command line argument specifies the AUTH to be set for
46         the object specified with -c.
47
48   References

Context Object Format

50       The type of a context object, whether it is a handle or file  name,  is
51       determined according to the following logic in-order:
52
53       · If the argument is a file path, then the file is loaded as a restored
54         TPM transient object.
55
56       · If the argument is a prefix match on one of:
57
58         · owner: the owner hierarchy
59
60         · platform: the platform hierarchy
61
62         · endorsement: the endorsement hierarchy
63
64         · lockout: the lockout control persistent object
65
66       · If the argument argument can be loaded as a number it will  be  treat
67         as a handle, e.g.  0x81010013 and used directly.OBJECT.
68

Authorization Formatting

70       Authorization  for  use  of an object in TPM2.0 can come in 3 different
71       forms: 1.  Password 2.  HMAC 3.  Sessions
72
73       NOTE: "Authorizations default to the EMPTY  PASSWORD  when  not  speci‐
74       fied".
75
76   Passwords
77       Passwords  are  interpreted  in  the following forms below using prefix
78       identifiers.
79
80       Note: By default passwords are assumed to be in the  string  form  when
81       they do not have a prefix.
82
83   String
84       A  string  password,  specified  by  prefix "str:" or it's absence (raw
85       string without prefix) is not interpreted, and is directly used for au‐
86       thorization.
87
88   Examples
89              foobar
90              str:foobar
91
92   Hex-string
93       A  hex-string  password, specified by prefix "hex:" is converted from a
94       hexidecimal form into a byte array form, thus allowing  passwords  with
95       non-printable and/or terminal un-friendly characters.
96
97   Example
98              hex:0x1122334455667788
99
100   File
101       A  file  based password, specified be prefix "file:" should be the path
102       of a file containing the password to be read by the tool or  a  "-"  to
103       use  stdin.   Storing  passwords in files prevents information leakage,
104       passwords passed as options can be read from the process list or common
105       shell history features.
106
107   Examples
108              # to use stdin and be prompted
109              file:-
110
111              # to use a file from a path
112              file:path/to/password/file
113
114              # to echo a password via stdin:
115              echo foobar | tpm2_tool -p file:-
116
117              # to use a bash here-string via stdin:
118
119              tpm2_tool -p file:- <<< foobar
120
121   Sessions
122       When  using  a policy session to authorize the use of an object, prefix
123       the option argument with the session keyword.  Then indicate a path  to
124       a session file that was created with tpm2_startauthsession(1).  Option‐
125       ally, if the session requires an auth value to be sent with the session
126       handle  (eg policy password), then append a + and a string as described
127       in the Passwords section.
128
129   Examples
130       To use a session context file called session.ctx.
131
132              session:session.ctx
133
134       To use a session context file called session.ctx AND send the authvalue
135       mypassword.
136
137              session:session.ctx+mypassword
138
139       To use a session context file called session.ctx AND send the HEX auth‐
140       value 0x11223344.
141
142              session:session.ctx+hex:11223344
143
144   PCR Authorizations
145       You can satisfy a PCR policy using the "pcr:" prefix and the PCR  mini‐
146       language.       The     PCR     minilanguage     is     as     follows:
147       <pcr-spec>=<raw-pcr-file>
148
149       The PCR spec is documented in in the section "PCR bank specifiers".
150
151       The raw-pcr-file is an optional the output of the raw PCR  contents  as
152       returned by tpm2_pcrread(1).
153
154       PCR bank specifiers (common/pcr.md)
155
156   Examples
157       To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifi‐
158       er of:
159
160              pcr:sha256:0,1,2,3
161
162       specifying AUTH.
163

COMMON OPTIONS

165       This collection of options are common to many programs and provide  in‐
166       formation that many users may expect.
167
168       · -h,  --help=[man|no-man]:  Display the tools manpage.  By default, it
169         attempts to invoke the manpager for the  tool,  however,  on  failure
170         will  output  a short tool summary.  This is the same behavior if the
171         "man" option argument is specified, however if explicit "man" is  re‐
172         quested,  the  tool  will  provide errors from man on stderr.  If the
173         "no-man" option if specified, or the manpager fails,  the  short  op‐
174         tions will be output to stdout.
175
176         To  successfully use the manpages feature requires the manpages to be
177         installed or on MANPATH, See man(1) for more details.
178
179       · -v, --version: Display version information for this  tool,  supported
180         tctis and exit.
181
182       · -V,  --verbose:  Increase the information that the tool prints to the
183         console during its execution.  When using this option  the  file  and
184         line number are printed.
185
186       · -Q, --quiet: Silence normal tool output to stdout.
187
188       · -Z, --enable-errata: Enable the application of errata fixups.  Useful
189         if an errata fixup needs to be applied to commands sent to  the  TPM.
190         Defining  the environment TPM2TOOLS_ENABLE_ERRATA is equivalent.  in‐
191         formation many users may expect.
192

TCTI Configuration

194       The TCTI or "Transmission Interface"  is  the  communication  mechanism
195       with  the TPM.  TCTIs can be changed for communication with TPMs across
196       different mediums.
197
198       To control the TCTI, the tools respect:
199
200       1. The command line option -T or --tcti
201
202       2. The environment variable: TPM2TOOLS_TCTI.
203
204       Note: The command line option always overrides  the  environment  vari‐
205       able.
206
207       The current known TCTIs are:
208
209       · tabrmd      -     The     resource     manager,     called     tabrmd
210         (https://github.com/tpm2-software/tpm2-abrmd).  Note that tabrmd  and
211         abrmd as a tcti name are synonymous.
212
213       · mssim  - Typically used for communicating to the TPM software simula‐
214         tor.
215
216       · device - Used when talking directly to a TPM device file.
217
218       · none - Do not initalize a connection with the TPM.  Some tools  allow
219         for off-tpm options and thus support not using a TCTI.  Tools that do
220         not support it will error when attempted to be used  without  a  TCTI
221         connection.   Does  not  support ANY options and MUST BE presented as
222         the exact text of "none".
223
224       The arguments to either the command  line  option  or  the  environment
225       variable are in the form:
226
227       <tcti-name>:<tcti-option-config>
228
229       Specifying  an  empty  string  for  either the <tcti-name> or <tcti-op‐
230       tion-config> results in the default being used for that portion respec‐
231       tively.
232
233   TCTI Defaults
234       When  a  TCTI  is not specified, the default TCTI is searched for using
235       dlopen(3) semantics.  The tools will  search  for  tabrmd,  device  and
236       mssim  TCTIs  IN THAT ORDER and USE THE FIRST ONE FOUND.  You can query
237       what TCTI will be chosen as the default by using the -v option to print
238       the  version information.  The "default-tcti" key-value pair will indi‐
239       cate which of the aforementioned TCTIs is the default.
240
241   Custom TCTIs
242       Any TCTI that implements the dynamic TCTI interface can be loaded.  The
243       tools internally use dlopen(3), and the raw tcti-name value is used for
244       the lookup.  Thus, this could be a path to the shared library, or a li‐
245       brary name as understood by dlopen(3) semantics.
246

TCTI OPTIONS

248       This collection of options are used to configure the various known TCTI
249       modules available:
250
251       · device: For the device TCTI, the TPM character device file for use by
252         the device TCTI can be specified.  The default is /dev/tpm0.
253
254         Example:    -T   device:/dev/tpm0   or   export   TPM2TOOLS_TCTI="de‐
255         vice:/dev/tpm0"
256
257       · mssim: For the mssim TCTI, the domain name or  IP  address  and  port
258         number  used  by  the  simulator  can  be specified.  The default are
259         127.0.0.1 and 2321.
260
261         Example: -T mssim:host=localhost,port=2321  or  export  TPM2TOOLS_TC‐
262         TI="mssim:host=localhost,port=2321"
263
264       · abrmd:  For  the abrmd TCTI, the configuration string format is a se‐
265         ries of simple key value pairs separated by a  ','  character.   Each
266         key and value string are separated by a '=' character.
267
268         · TCTI abrmd supports two keys:
269
270           1. 'bus_name'  :  The  name  of  the  tabrmd  service on the bus (a
271              string).
272
273           2. 'bus_type' : The type of the dbus instance (a string) limited to
274              'session' and 'system'.
275
276         Specify  the tabrmd tcti name and a config string of bus_name=com.ex‐
277         ample.FooBar:
278
279         \--tcti=tabrmd:bus_name=com.example.FooBar
280
281         Specify the default (abrmd) tcti and a config string of bus_type=ses‐
282         sion:
283
284         \--tcti:bus_type=session
285
286         NOTE:  abrmd  and tabrmd are synonymous.  the various known TCTI mod‐
287         ules.
288

EXAMPLES

290   Set owner, endorsement and lockout authorizations to newpass
291              tpm2_changeauth -c owner newpass
292              tpm2_changeauth -c endorsement newpass
293              tpm2_changeauth -c lockout newpass
294
295   Change owner, endorsement and lockout authorizations
296              tpm2_changeauth -c o -p newpass newerpass
297              tpm2_changeauth -c e -p newpass newerpass
298              tpm2_changeauth -c l -p newpass newerpass
299
300   Set owner authorization to empty password
301              tpm2_changeauth -c o -p oldpass
302
303   Modify authorization for a loadable transient object
304              tpm2_createprimary -Q -C o -c prim.ctx
305
306              tpm2_create -Q -g sha256 -G aes -u key.pub -r key.priv -C prim.ctx
307
308              tpm2_load -C prim.ctx -u key.pub -r key.priv -n key.name -c key.ctx
309
310              tpm2_changeauth -c key.ctx -C prim.ctx -r key.priv newkeyauth
311
312   Modify authorization for a NV Index
313       Requires Extended Session Support.
314
315              tpm2_startauthsession -S session.ctx
316
317              tpm2_policycommandcode -S session.ctx -L policy.nvchange TPM2_CC_NV_ChangeAuth
318              tpm2_flushcontext session.ctx
319
320              NVIndex=0x1500015
321              tpm2_nvdefine   $NVIndex -C o -s 32 -a "authread|authwrite" -L policy.nvchange
322              tpm2_startauthsession \--policy-session -S session.ctx
323
324              tpm2_policycommandcode -S session.ctx -L policy.nvchange TPM2_CC_NV_ChangeAuth
325
326              tpm2_changeauth -p session:session.ctx -c $NVIndex newindexauth
327

Returns

329       Tools can return any of the following codes:
330
331       · 0 - Success.
332
333       · 1 - General non-specific error.
334
335       · 2 - Options handling error.
336
337       · 3 - Authentication error.
338
339       · 4 - TCTI related error.
340
341       · 5 - Non supported scheme.  Applicable to tpm2_testparams.
342

BUGS

344       Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
345

HELP

347       See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)
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351tpm2-tools                                                  tpm2_changeauth(1)
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