1tpm2_changeauth(1)          General Commands Manual         tpm2_changeauth(1)
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3
4

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       · ARGUMENT  the  command line argument specifies the AUTH to be set for
40         the object specified with -c.
41
42   References

Context Object Format

44       The type of a context object, whether it is a handle or file  name,  is
45       determined according to the following logic in-order:
46
47       · If the argument is a file path, then the file is loaded as a restored
48         TPM transient object.
49
50       · If the argument is a prefix match on one of:
51
52         · owner: the owner hierarchy
53
54         · platform: the platform hierarchy
55
56         · endorsement: the endorsement hierarchy
57
58         · lockout: the lockout control persistent object
59
60       · If the argument argument can be loaded as a number it will  be  treat
61         as a handle, e.g.  0x81010013 and used directly.OBJECT.
62

Authorization Formatting

64       Authorization  for  use  of an object in TPM2.0 can come in 3 different
65       forms: 1.  Password 2.  HMAC 3.  Sessions
66
67       NOTE: "Authorizations default to the EMPTY  PASSWORD  when  not  speci‐
68       fied".
69
70   Passwords
71       Passwords  are  interpreted  in  the following forms below using prefix
72       identifiers.
73
74       Note: By default passwords are assumed to be in the  string  form  when
75       they do not have a prefix.
76
77   String
78       A  string  password,  specified  by  prefix "str:" or it's absence (raw
79       string without prefix) is not interpreted, and is directly used for au‐
80       thorization.
81
82   Examples
83              foobar
84              str:foobar
85
86   Hex-string
87       A  hex-string  password, specified by prefix "hex:" is converted from a
88       hexidecimal form into a byte array form, thus allowing  passwords  with
89       non-printable and/or terminal un-friendly characters.
90
91   Example
92              hex:0x1122334455667788
93
94   File
95       A  file  based password, specified be prefix "file:" should be the path
96       of a file containing the password to be read by the tool or  a  "-"  to
97       use  stdin.   Storing  passwords in files prevents information leakage,
98       passwords passed as options can be read from the process list or common
99       shell history features.
100
101   Examples
102              # to use stdin and be prompted
103              file:-
104
105              # to use a file from a path
106              file:path/to/password/file
107
108              # to echo a password via stdin:
109              echo foobar | tpm2_tool -p file:-
110
111              # to use a bash here-string via stdin:
112
113              tpm2_tool -p file:- <<< foobar
114
115   Sessions
116       When  using  a policy session to authorize the use of an object, prefix
117       the option argument with the session keyword.  Then indicate a path  to
118       a session file that was created with tpm2_startauthsession(1).  Option‐
119       ally, if the session requires an auth value to be sent with the session
120       handle  (eg policy password), then append a + and a string as described
121       in the Passwords section.
122
123   Examples
124       To use a session context file called session.ctx.
125
126              session:session.ctx
127
128       To use a session context file called session.ctx AND send the authvalue
129       mypassword.
130
131              session:session.ctx+mypassword
132
133       To use a session context file called session.ctx AND send the HEX auth‐
134       value 0x11223344.
135
136              session:session.ctx+hex:11223344
137
138   PCR Authorizations
139       You can satisfy a PCR policy using the "pcr:" prefix and the PCR  mini‐
140       language.       The     PCR     minilanguage     is     as     follows:
141       <pcr-spec>=<raw-pcr-file>
142
143       The PCR spec is documented in in the section "PCR bank specifiers".
144
145       The raw-pcr-file is an optional the output of the raw PCR  contents  as
146       returned by tpm2_pcrread(1).
147
148       PCR bank specifiers (common/pcr.md)
149
150   Examples
151       To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifi‐
152       er of:
153
154              pcr:sha256:0,1,2,3
155
156       specifying AUTH.
157

COMMON OPTIONS

159       This collection of options are common to many programs and provide  in‐
160       formation that many users may expect.
161
162       · -h,  --help=[man|no-man]:  Display the tools manpage.  By default, it
163         attempts to invoke the manpager for the  tool,  however,  on  failure
164         will  output  a short tool summary.  This is the same behavior if the
165         "man" option argument is specified, however if explicit "man" is  re‐
166         quested,  the  tool  will  provide errors from man on stderr.  If the
167         "no-man" option if specified, or the manpager fails,  the  short  op‐
168         tions will be output to stdout.
169
170         To  successfully use the manpages feature requires the manpages to be
171         installed or on MANPATH, See man(1) for more details.
172
173       · -v, --version: Display version information for this  tool,  supported
174         tctis and exit.
175
176       · -V,  --verbose:  Increase the information that the tool prints to the
177         console during its execution.  When using this option  the  file  and
178         line number are printed.
179
180       · -Q, --quiet: Silence normal tool output to stdout.
181
182       · -Z, --enable-errata: Enable the application of errata fixups.  Useful
183         if an errata fixup needs to be applied to commands sent to  the  TPM.
184         Defining  the environment TPM2TOOLS_ENABLE_ERRATA is equivalent.  in‐
185         formation many users may expect.
186

TCTI Configuration

188       The TCTI or "Transmission Interface"  is  the  communication  mechanism
189       with  the TPM.  TCTIs can be changed for communication with TPMs across
190       different mediums.
191
192       To control the TCTI, the tools respect:
193
194       1. The command line option -T or --tcti
195
196       2. The environment variable: TPM2TOOLS_TCTI.
197
198       Note: The command line option always overrides  the  environment  vari‐
199       able.
200
201       The current known TCTIs are:
202
203       · tabrmd      -     The     resource     manager,     called     tabrmd
204         (https://github.com/tpm2-software/tpm2-abrmd).  Note that tabrmd  and
205         abrmd as a tcti name are synonymous.
206
207       · mssim  - Typically used for communicating to the TPM software simula‐
208         tor.
209
210       · device - Used when talking directly to a TPM device file.
211
212       · none - Do not initalize a connection with the TPM.  Some tools  allow
213         for off-tpm options and thus support not using a TCTI.  Tools that do
214         not support it will error when attempted to be used  without  a  TCTI
215         connection.   Does  not  support ANY options and MUST BE presented as
216         the exact text of "none".
217
218       The arguments to either the command  line  option  or  the  environment
219       variable are in the form:
220
221       <tcti-name>:<tcti-option-config>
222
223       Specifying  an  empty  string  for  either the <tcti-name> or <tcti-op‐
224       tion-config> results in the default being used for that portion respec‐
225       tively.
226
227   TCTI Defaults
228       When  a  TCTI  is not specified, the default TCTI is searched for using
229       dlopen(3) semantics.  The tools will  search  for  tabrmd,  device  and
230       mssim  TCTIs  IN THAT ORDER and USE THE FIRST ONE FOUND.  You can query
231       what TCTI will be chosen as the default by using the -v option to print
232       the  version information.  The "default-tcti" key-value pair will indi‐
233       cate which of the aforementioned TCTIs is the default.
234
235   Custom TCTIs
236       Any TCTI that implements the dynamic TCTI interface can be loaded.  The
237       tools internally use dlopen(3), and the raw tcti-name value is used for
238       the lookup.  Thus, this could be a path to the shared library, or a li‐
239       brary name as understood by dlopen(3) semantics.
240

TCTI OPTIONS

242       This collection of options are used to configure the various known TCTI
243       modules available:
244
245       · device: For the device TCTI, the TPM character device file for use by
246         the device TCTI can be specified.  The default is /dev/tpm0.
247
248         Example:    -T   device:/dev/tpm0   or   export   TPM2TOOLS_TCTI="de‐
249         vice:/dev/tpm0"
250
251       · mssim: For the mssim TCTI, the domain name or  IP  address  and  port
252         number  used  by  the  simulator  can  be specified.  The default are
253         127.0.0.1 and 2321.
254
255         Example: -T mssim:host=localhost,port=2321  or  export  TPM2TOOLS_TC‐
256         TI="mssim:host=localhost,port=2321"
257
258       · abrmd:  For  the abrmd TCTI, the configuration string format is a se‐
259         ries of simple key value pairs separated by a  ','  character.   Each
260         key and value string are separated by a '=' character.
261
262         · TCTI abrmd supports two keys:
263
264           1. 'bus_name'  :  The  name  of  the  tabrmd  service on the bus (a
265              string).
266
267           2. 'bus_type' : The type of the dbus instance (a string) limited to
268              'session' and 'system'.
269
270         Specify  the tabrmd tcti name and a config string of bus_name=com.ex‐
271         ample.FooBar:
272
273         \--tcti=tabrmd:bus_name=com.example.FooBar
274
275         Specify the default (abrmd) tcti and a config string of bus_type=ses‐
276         sion:
277
278         \--tcti:bus_type=session
279
280         NOTE:  abrmd  and tabrmd are synonymous.  the various known TCTI mod‐
281         ules.
282

EXAMPLES

284   Set owner, endorsement and lockout authorizations to newpass
285              tpm2_changeauth -c owner newpass
286              tpm2_changeauth -c endorsement newpass
287              tpm2_changeauth -c lockout newpass
288
289   Change owner, endorsement and lockout authorizations
290              tpm2_changeauth -c o -p newpass newerpass
291              tpm2_changeauth -c e -p newpass newerpass
292              tpm2_changeauth -c l -p newpass newerpass
293
294   Set owner authorization to empty password
295              tpm2_changeauth -c o -p oldpass
296
297   Modify authorization for a loadable transient object
298              tpm2_createprimary -Q -C o -c prim.ctx
299
300              tpm2_create -Q -g sha256 -G aes -u key.pub -r key.priv -C prim.ctx
301
302              tpm2_load -C prim.ctx -u key.pub -r key.priv -n key.name -c key.ctx
303
304              tpm2_changeauth -c key.ctx -C prim.ctx -r key.priv newkeyauth
305
306   Modify authorization for a NV Index
307       Requires Extended Session Support.
308
309              tpm2_startauthsession -S session.ctx
310
311              tpm2_policycommandcode -S session.ctx -L policy.nvchange TPM2_CC_NV_ChangeAuth
312              tpm2_flushcontext session.ctx
313
314              NVIndex=0x1500015
315              tpm2_nvdefine   $NVIndex -C o -s 32 -a "authread|authwrite" -L policy.nvchange
316              tpm2_startauthsession \--policy-session -S session.ctx
317
318              tpm2_policycommandcode -S session.ctx -L policy.nvchange TPM2_CC_NV_ChangeAuth
319
320              tpm2_changeauth -p session:session.ctx -c $NVIndex newindexauth
321

Returns

323       Tools can return any of the following codes:
324
325       · 0 - Success.
326
327       · 1 - General non-specific error.
328
329       · 2 - Options handling error.
330
331       · 3 - Authentication error.
332
333       · 4 - TCTI related error.
334
335       · 5 - Non supported scheme.  Applicable to tpm2_testparams.
336

BUGS

338       Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
339

HELP

341       See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)
342
343
344
345tpm2-tools                                                  tpm2_changeauth(1)