1tpm2_policyauthvalue(1)     General Commands Manual    tpm2_policyauthvalue(1)
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NAME

6       tpm2_policyauthvalue(1) - Enables binding a policy to the authorization
7       value of the authorized TPM object.
8

SYNOPSIS

10       tpm2_policyauthvalue [OPTIONS]
11

DESCRIPTION

13       tpm2_policyauthvalue(1) - Enables a policy that requires  the  object's
14       authentication passphrase be provided.  This is equivalent to authenti‐
15       cating using the object passphrase in plaintext or HMAC.   It  enforces
16       it  as a policy.  It provides a mechanism to allow for password authen‐
17       tication when an object only allows policy based authorization, ie  ob‐
18       ject attribute "userwithauth" is 0.
19

OPTIONS

21-L, --policy=FILE:
22
23         File to save the compounded policy digest.
24
25-S, --session=FILE:
26
27         The  policy  session  file  generated via the -S option to tpm2_star‐
28         tauthsession(1).
29
30   References

COMMON OPTIONS

32       This collection of options are common to many programs and provide  in‐
33       formation that many users may expect.
34
35-h,  --help=[man|no-man]:  Display the tools manpage.  By default, it
36         attempts to invoke the manpager for the  tool,  however,  on  failure
37         will  output  a short tool summary.  This is the same behavior if the
38         "man" option argument is specified, however if explicit "man" is  re‐
39         quested,  the  tool  will  provide errors from man on stderr.  If the
40         "no-man" option if specified, or the manpager fails,  the  short  op‐
41         tions will be output to stdout.
42
43         To  successfully use the manpages feature requires the manpages to be
44         installed or on MANPATH, See man(1) for more details.
45
46-v, --version: Display version information for this  tool,  supported
47         tctis and exit.
48
49-V,  --verbose:  Increase the information that the tool prints to the
50         console during its execution.  When using this option  the  file  and
51         line number are printed.
52
53-Q, --quiet: Silence normal tool output to stdout.
54
55-Z, --enable-errata: Enable the application of errata fixups.  Useful
56         if an errata fixup needs to be applied to commands sent to  the  TPM.
57         Defining  the environment TPM2TOOLS_ENABLE_ERRATA is equivalent.  in‐
58         formation many users may expect.
59

TCTI Configuration

61       The TCTI or "Transmission Interface"  is  the  communication  mechanism
62       with  the TPM.  TCTIs can be changed for communication with TPMs across
63       different mediums.
64
65       To control the TCTI, the tools respect:
66
67       1. The command line option -T or --tcti
68
69       2. The environment variable: TPM2TOOLS_TCTI.
70
71       Note: The command line option always overrides  the  environment  vari‐
72       able.
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74       The current known TCTIs are:
75
76       • tabrmd      -     The     resource     manager,     called     tabrmd
77         (https://github.com/tpm2-software/tpm2-abrmd).  Note that tabrmd  and
78         abrmd as a tcti name are synonymous.
79
80       • mssim  - Typically used for communicating to the TPM software simula‐
81         tor.
82
83       • device - Used when talking directly to a TPM device file.
84
85       • none - Do not initalize a connection with the TPM.  Some tools  allow
86         for off-tpm options and thus support not using a TCTI.  Tools that do
87         not support it will error when attempted to be used  without  a  TCTI
88         connection.   Does  not  support ANY options and MUST BE presented as
89         the exact text of "none".
90
91       The arguments to either the command  line  option  or  the  environment
92       variable are in the form:
93
94       <tcti-name>:<tcti-option-config>
95
96       Specifying  an  empty  string  for  either the <tcti-name> or <tcti-op‐
97       tion-config> results in the default being used for that portion respec‐
98       tively.
99
100   TCTI Defaults
101       When  a  TCTI  is not specified, the default TCTI is searched for using
102       dlopen(3) semantics.  The tools will  search  for  tabrmd,  device  and
103       mssim  TCTIs  IN THAT ORDER and USE THE FIRST ONE FOUND.  You can query
104       what TCTI will be chosen as the default by using the -v option to print
105       the  version information.  The "default-tcti" key-value pair will indi‐
106       cate which of the aforementioned TCTIs is the default.
107
108   Custom TCTIs
109       Any TCTI that implements the dynamic TCTI interface can be loaded.  The
110       tools internally use dlopen(3), and the raw tcti-name value is used for
111       the lookup.  Thus, this could be a path to the shared library, or a li‐
112       brary name as understood by dlopen(3) semantics.
113

TCTI OPTIONS

115       This collection of options are used to configure the various known TCTI
116       modules available:
117
118device: For the device TCTI, the TPM character device file for use by
119         the device TCTI can be specified.  The default is /dev/tpm0.
120
121         Example:    -T   device:/dev/tpm0   or   export   TPM2TOOLS_TCTI="de‐
122         vice:/dev/tpm0"
123
124        mssim: For the mssim TCTI, the domain name or  IP  address  and  port
125         number  used  by  the  simulator  can  be specified.  The default are
126         127.0.0.1 and 2321.
127
128         Example: -T mssim:host=localhost,port=2321  or  export  TPM2TOOLS_TC‐
129         TI="mssim:host=localhost,port=2321"
130
131        abrmd:  For  the abrmd TCTI, the configuration string format is a se‐
132         ries of simple key value pairs separated by a  ','  character.   Each
133         key and value string are separated by a '=' character.
134
135         • TCTI abrmd supports two keys:
136
137           1. 'bus_name'  :  The  name  of  the  tabrmd  service on the bus (a
138              string).
139
140           2. 'bus_type' : The type of the dbus instance (a string) limited to
141              'session' and 'system'.
142
143         Specify  the tabrmd tcti name and a config string of bus_name=com.ex‐
144         ample.FooBar:
145
146         \--tcti=tabrmd:bus_name=com.example.FooBar
147
148         Specify the default (abrmd) tcti and a config string of bus_type=ses‐
149         sion:
150
151         \--tcti:bus_type=session
152
153         NOTE:  abrmd  and tabrmd are synonymous.  the various known TCTI mod‐
154         ules.
155

EXAMPLES

157       We want to authenticate using the TPM objects plaintext  authentication
158       value.  While we could authenticate with an ephemeral password session,
159       in this example we will authenticate with the plaintext passphrase in a
160       policy session instead using the tpm2_policyauthvalue(1) tool.
161
162   Create the password policy
163              tpm2_startauthsession -S session.dat
164
165              tpm2_policyauthvalue -S session.dat -L policy.dat
166
167              tpm2_flushcontext session.dat
168
169   Create the object with a passphrase and the password policy
170              tpm2_createprimary -C o -c prim.ctx
171
172              tpm2_create -g sha256 -G aes -u key.pub -r key.priv -C prim.ctx -L policy.dat \
173                -p testpswd
174
175   Authenticate with plaintext passphrase input
176              tpm2_load -C prim.ctx -u key.pub -r key.priv -n key.name -c key.ctx
177
178              echo "plaintext" > plain.txt
179              tpm2_encryptdecrypt -c key.ctx -o encrypt.out plain.txt -p testpswd
180
181   Authenticate with password and the policy
182              tpm2_startauthsession --policy-session -S session.dat
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184              tpm2_policyauthvalue -S session.dat
185
186              tpm2_encryptdecrypt -c key.ctx -o encrypt.out -p session:session.dat+testpswd \
187              plain.txt
188
189              tpm2_flushcontext session.dat
190

Returns

192       Tools can return any of the following codes:
193
194       • 0 - Success.
195
196       • 1 - General non-specific error.
197
198       • 2 - Options handling error.
199
200       • 3 - Authentication error.
201
202       • 4 - TCTI related error.
203
204       • 5 - Non supported scheme.  Applicable to tpm2_testparams.
205

Limitations

207       It  expects  a session to be already established via tpm2_startauthses‐
208       sion(1) and requires one of the following:
209
210       • direct device access
211
212       • extended session support with tpm2-abrmd.
213
214       Without it, most resource managers will not save session state  between
215       command invocations.
216

BUGS

218       Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
219

HELP

221       See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)
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225tpm2-tools                                             tpm2_policyauthvalue(1)
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