1tpm2_readpublic(1) General Commands Manual tpm2_readpublic(1)
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6 tpm2_readpublic(1) - Read the public area of a loaded object.
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9 tpm2_readpublic [OPTIONS]
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12 tpm2_readpublic(1) - Reads the public area of a loaded object.
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15 · -c, --object-context=OBJECT:
16 Context object for the object to read.
18 · -n, --name=FILE:
20 An optional file to save the name structure of the object.
22 · -f, --format=FORMAT:
24 Public key format.
26 · -o, --output=FILE:
28 The output file path, recording the public portion of the object.
30 · -t, --serialized-handle=HANDLE:
32 If the object to be read is a persistent object specified by a raw
34 handle, optionally save the serialized handle for use later. This
35 routine does NOT verify the name of the object being read. Callers
36 should ensure that the contents of name match the expected objects
37 name.
38 References
41 The type of a context object, whether it is a handle or file name, is
42 determined according to the following logic in-order:
43 · If the argument is a file path, then the file is loaded as a restored
45 TPM transient object.
46 · If the argument is a prefix match on one of:
48 · owner: the owner hierarchy
50 · platform: the platform hierarchy
52 · endorsement: the endorsement hierarchy
54 · lockout: the lockout control persistent object
56 · If the argument argument can be loaded as a number it will be treat
58 as a handle, e.g. 0x81010013 and used directly.OBJECT.
59
61 This collection of options are common to many programs and provide in‐
62 formation that many users may expect.
63 · -h, --help=[man|no-man]: Display the tools manpage. By default, it
65 attempts to invoke the manpager for the tool, however, on failure
66 will output a short tool summary. This is the same behavior if the
67 "man" option argument is specified, however if explicit "man" is re‐
68 quested, the tool will provide errors from man on stderr. If the
69 "no-man" option if specified, or the manpager fails, the short op‐
70 tions will be output to stdout.
71 To successfully use the manpages feature requires the manpages to be
73 installed or on MANPATH, See man(1) for more details.
74 · -v, --version: Display version information for this tool, supported
76 tctis and exit.
77 · -V, --verbose: Increase the information that the tool prints to the
79 console during its execution. When using this option the file and
80 line number are printed.
81 · -Q, --quiet: Silence normal tool output to stdout.
83 · -Z, --enable-errata: Enable the application of errata fixups. Useful
85 if an errata fixup needs to be applied to commands sent to the TPM.
86 Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent. in‐
87 formation many users may expect.
88
90 The TCTI or "Transmission Interface" is the communication mechanism
91 with the TPM. TCTIs can be changed for communication with TPMs across
92 different mediums.
93 To control the TCTI, the tools respect:
95 1. The command line option -T or --tcti
97 2. The environment variable: TPM2TOOLS_TCTI.
99 Note: The command line option always overrides the environment vari‐
101 able.
102 The current known TCTIs are:
104 · tabrmd - The resource manager, called tabrmd
106 (https://github.com/tpm2-software/tpm2-abrmd). Note that tabrmd and
107 abrmd as a tcti name are synonymous.
108 · mssim - Typically used for communicating to the TPM software simula‐
110 tor.
111 · device - Used when talking directly to a TPM device file.
113 · none - Do not initalize a connection with the TPM. Some tools allow
115 for off-tpm options and thus support not using a TCTI. Tools that do
116 not support it will error when attempted to be used without a TCTI
117 connection. Does not support ANY options and MUST BE presented as
118 the exact text of "none".
119 The arguments to either the command line option or the environment
121 variable are in the form:
122 <tcti-name>:<tcti-option-config>
124 Specifying an empty string for either the <tcti-name> or <tcti-op‐
126 tion-config> results in the default being used for that portion respec‐
127 tively.
128 TCTI Defaults
130 When a TCTI is not specified, the default TCTI is searched for using
131 dlopen(3) semantics. The tools will search for tabrmd, device and
132 mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND. You can query
133 what TCTI will be chosen as the default by using the -v option to print
134 the version information. The "default-tcti" key-value pair will indi‐
135 cate which of the aforementioned TCTIs is the default.
136 Custom TCTIs
138 Any TCTI that implements the dynamic TCTI interface can be loaded. The
139 tools internally use dlopen(3), and the raw tcti-name value is used for
140 the lookup. Thus, this could be a path to the shared library, or a li‐
141 brary name as understood by dlopen(3) semantics.
142
144 This collection of options are used to configure the various known TCTI
145 modules available:
146 · device: For the device TCTI, the TPM character device file for use by
148 the device TCTI can be specified. The default is /dev/tpm0.
149 Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI="de‐
151 vice:/dev/tpm0"
152 · mssim: For the mssim TCTI, the domain name or IP address and port
154 number used by the simulator can be specified. The default are
155 127.0.0.1 and 2321.
156 Example: -T mssim:host=localhost,port=2321 or export TPM2TOOLS_TC‐
158 TI="mssim:host=localhost,port=2321"
159 · abrmd: For the abrmd TCTI, the configuration string format is a se‐
161 ries of simple key value pairs separated by a ',' character. Each
162 key and value string are separated by a '=' character.
163 · TCTI abrmd supports two keys:
165 1. 'bus_name' : The name of the tabrmd service on the bus (a
167 string).
168 2. 'bus_type' : The type of the dbus instance (a string) limited to
170 'session' and 'system'.
171 Specify the tabrmd tcti name and a config string of bus_name=com.ex‐
173 ample.FooBar:
174 \--tcti=tabrmd:bus_name=com.example.FooBar
176 Specify the default (abrmd) tcti and a config string of bus_type=ses‐
178 sion:
179 \--tcti:bus_type=session
181 NOTE: abrmd and tabrmd are synonymous. the various known TCTI mod‐
183 ules. # EXAMPLES
184 Create a primary object and read the public structure in an openssl
186 compliant format
187 tpm2_createprimary -c primary.ctx
189 tpm2_readpublic -c primary.ctx -o output.dat -f pem
190 Serialize an existing persistent object handle to disk for later use
192 This work-flow is primarily intended for existing persistent TPM ob‐
193 jects. This work-flow does not verify that the name of the serialized
194 object matches the expected, and thus the serialized handle could be
195 pointing to an attacker controlled object if no verification is done.
196 If you are creating an object from scratch, save the serialized handle
197 when making the object persistent.
198 We assume that an object has already been persisted, for example via:
200 # We assume that an object has already been persisted, for example
202 tpm2_createprimary -c primary.ctx
203 # context files have all the information for the TPM to verify the object
205 tpm2_evictcontrol -c primary.ctx
206 persistent-handle: 0x81000001
207 action: persisted
208 Next use the persistent handle to get a serialized handle:
210 # The persistent handle output could be at an attacker controlled object,
212 # best practice is to use the option "-o: for tpm2_evictcontrol to get a
213 # serialized handle instead.
214 tpm2_readpublic -c 0x81000001 -o output.dat -f pem -t primary.handle
216 # use this verified handle in an encrypted session with the tpm
218 tpm2_startauthsession --policy-session -S session.ctx -c primary.handle
219 For new objects, its best to use all serialized handles.
221
223 Tools can return any of the following codes:
224 · 0 - Success.
226 · 1 - General non-specific error.
228 · 2 - Options handling error.
230 · 3 - Authentication error.
232 · 4 - TCTI related error.
234 · 5 - Non supported scheme. Applicable to tpm2_testparams.
236
238 Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
239
241 See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)
242tpm2-tools tpm2_readpublic(1)