csu3_am335x/EVSE/GPL/tpm2-tools-5.1/man/man1/tpm2_readpublic.1

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.TH "tpm2_readpublic" "1" "" "tpm2\-tools" "General Commands Manual"
.hy
.SH NAME
.PP
\f[B]tpm2_readpublic\f[](1) \- Read the public area of a loaded object.
.SH SYNOPSIS
.PP
\f[B]tpm2_readpublic\f[] [\f[I]OPTIONS\f[]]
.SH DESCRIPTION
.PP
\f[B]tpm2_readpublic\f[](1) \- Reads the public area of a loaded object.
.SH OPTIONS
.IP \[bu] 2
\f[B]\-c\f[], \f[B]\-\-object\-context\f[]=\f[I]OBJECT\f[]:
.RS 2
.PP
Context object for the object to read.
.RE
.IP \[bu] 2
\f[B]\-n\f[], \f[B]\-\-name\f[]=\f[I]FILE\f[]:
.RS 2
.PP
An optional file to save the name structure of the object.
.RE
.IP \[bu] 2
\f[B]\-f\f[], \f[B]\-\-format\f[]:
.RS 2
.PP
Format selection for the public key output file.
\[aq]tss\[aq] (the default) will output a binary blob according to the
TPM 2.0 Specification.
\[aq]pem\[aq] will output an OpenSSL compatible PEM encoded public key.
\[aq]der\[aq] will output an OpenSSL compatible DER encoded public key.
\[aq]tpmt\[aq] will output a binary blob of the TPMT_PUBLIC struct
referenced by TPM 2.0 specs.
.PP
Public key format.
.RE
.IP \[bu] 2
\f[B]\-o\f[], \f[B]\-\-output\f[]=\f[I]FILE\f[]:
.RS 2
.PP
The output file path, recording the public portion of the object.
.RE
.IP \[bu] 2
\f[B]\-t\f[], \f[B]\-\-serialized\-handle\f[]=\f[I]HANDLE\f[]:
.RS 2
.PP
If the object to be read is a persistent object specified by a raw
handle, optionally save the serialized handle for use later.
This routine does NOT verify the name of the object being read.
Callers should ensure that the contents of name match the expected
objects name.
.RE
.IP \[bu] 2
\f[B]\-q\f[], \f[B]\-\-qualified\-name\f[]=\f[I]FILE\f[]:
.RS 2
.PP
Saves the qualified name of the object to \f[I]FILE\f[].
The qualified name of the object is the name algorithm hash of the
parents qualified and the objects name.
Thus the qualified name of the object serves as proof of the objects
parents.
.RE
.SS References
.SH Context Object Format
.PP
The type of a context object, whether it is a handle or file name, is
determined according to the following logic \f[I]in\-order\f[]:
.IP \[bu] 2
If the argument is a file path, then the file is loaded as a restored
TPM transient object.
.IP \[bu] 2
If the argument is a \f[I]prefix\f[] match on one of:
.RS 2
.IP \[bu] 2
owner: the owner hierarchy
.IP \[bu] 2
platform: the platform hierarchy
.IP \[bu] 2
endorsement: the endorsement hierarchy
.IP \[bu] 2
lockout: the lockout control persistent object
.RE
.IP \[bu] 2
If the argument argument can be loaded as a number it will be treat as a
handle, e.g.
0x81010013 and used directly.\f[I]OBJECT\f[].
.SH COMMON OPTIONS
.PP
This collection of options are common to many programs and provide
information that many users may expect.
.IP \[bu] 2
\f[B]\-h\f[], \f[B]\-\-help=[man|no\-man]\f[]: Display the tools
manpage.
By default, it attempts to invoke the manpager for the tool, however, on
failure will output a short tool summary.
This is the same behavior if the "man" option argument is specified,
however if explicit "man" is requested, the tool will provide errors
from man on stderr.
If the "no\-man" option if specified, or the manpager fails, the short
options will be output to stdout.
.RS 2
.PP
To successfully use the manpages feature requires the manpages to be
installed or on \f[I]MANPATH\f[], See man(1) for more details.
.RE
.IP \[bu] 2
\f[B]\-v\f[], \f[B]\-\-version\f[]: Display version information for this
tool, supported tctis and exit.
.IP \[bu] 2
\f[B]\-V\f[], \f[B]\-\-verbose\f[]: Increase the information that the
tool prints to the console during its execution.
When using this option the file and line number are printed.
.IP \[bu] 2
\f[B]\-Q\f[], \f[B]\-\-quiet\f[]: Silence normal tool output to stdout.
.IP \[bu] 2
\f[B]\-Z\f[], \f[B]\-\-enable\-errata\f[]: Enable the application of
errata fixups.
Useful if an errata fixup needs to be applied to commands sent to the
TPM.
Defining the environment TPM2TOOLS_ENABLE_ERRATA is equivalent.
information many users may expect.
.SH TCTI Configuration
.PP
The TCTI or "Transmission Interface" is the communication mechanism with
the TPM.
TCTIs can be changed for communication with TPMs across different
mediums.
.PP
To control the TCTI, the tools respect:
.IP "1." 3
The command line option \f[B]\-T\f[] or \f[B]\-\-tcti\f[]
.IP "2." 3
The environment variable: \f[I]TPM2TOOLS_TCTI\f[].
.PP
\f[B]Note:\f[] The command line option always overrides the environment
variable.
.PP
The current known TCTIs are:
.IP \[bu] 2
tabrmd \- The resource manager, called
tabrmd (https://github.com/tpm2-software/tpm2-abrmd).
Note that tabrmd and abrmd as a tcti name are synonymous.
.IP \[bu] 2
mssim \- Typically used for communicating to the TPM software simulator.
.IP \[bu] 2
device \- Used when talking directly to a TPM device file.
.IP \[bu] 2
none \- Do not initalize a connection with the TPM.
Some tools allow for off\-tpm options and thus support not using a TCTI.
Tools that do not support it will error when attempted to be used
without a TCTI connection.
Does not support \f[I]ANY\f[] options and \f[I]MUST BE\f[] presented as
the exact text of "none".
.PP
The arguments to either the command line option or the environment
variable are in the form:
.PP
\f[C]<tcti\-name>:<tcti\-option\-config>\f[]
.PP
Specifying an empty string for either the \f[C]<tcti\-name>\f[] or
\f[C]<tcti\-option\-config>\f[] results in the default being used for
that portion respectively.
.SS TCTI Defaults
.PP
When a TCTI is not specified, the default TCTI is searched for using
\f[I]dlopen(3)\f[] semantics.
The tools will search for \f[I]tabrmd\f[], \f[I]device\f[] and
\f[I]mssim\f[] TCTIs \f[B]IN THAT ORDER\f[] and \f[B]USE THE FIRST ONE
FOUND\f[].
You can query what TCTI will be chosen as the default by using the
\f[B]\-v\f[] option to print the version information.
The "default\-tcti" key\-value pair will indicate which of the
aforementioned TCTIs is the default.
.SS Custom TCTIs
.PP
Any TCTI that implements the dynamic TCTI interface can be loaded.
The tools internally use \f[I]dlopen(3)\f[], and the raw
\f[I]tcti\-name\f[] value is used for the lookup.
Thus, this could be a path to the shared library, or a library name as
understood by \f[I]dlopen(3)\f[] semantics.
.SH TCTI OPTIONS
.PP
This collection of options are used to configure the various known TCTI
modules available:
.IP \[bu] 2
\f[B]device\f[]: For the device TCTI, the TPM character device file for
use by the device TCTI can be specified.
The default is \f[I]/dev/tpm0\f[].
.RS 2
.PP
Example: \f[B]\-T device:/dev/tpm0\f[] or \f[B]export
\f[I]TPM2TOOLS_TCTI\f[]="device:/dev/tpm0"\f[]
.RE
.IP \[bu] 2
\f[B]mssim\f[]: For the mssim TCTI, the domain name or IP address and
port number used by the simulator can be specified.
The default are 127.0.0.1 and 2321.
.RS 2
.PP
Example: \f[B]\-T mssim:host=localhost,port=2321\f[] or \f[B]export
\f[I]TPM2TOOLS_TCTI\f[]="mssim:host=localhost,port=2321"\f[]
.RE
.IP \[bu] 2
\f[B]abrmd\f[]: For the abrmd TCTI, the configuration string format is a
series of simple key value pairs separated by a \[aq],\[aq] character.
Each key and value string are separated by a \[aq]=\[aq] character.
.RS 2
.IP \[bu] 2
TCTI abrmd supports two keys:
.RS 2
.IP "1." 3
\[aq]bus_name\[aq] : The name of the tabrmd service on the bus (a
string).
.IP "2." 3
\[aq]bus_type\[aq] : The type of the dbus instance (a string) limited to
\[aq]session\[aq] and \[aq]system\[aq].
.RE
.PP
Specify the tabrmd tcti name and a config string of
\f[C]bus_name=com.example.FooBar\f[]:
.PP
\f[C]\\\-\-tcti=tabrmd:bus_name=com.example.FooBar\f[]
.PP
Specify the default (abrmd) tcti and a config string of
\f[C]bus_type=session\f[]:
.PP
\f[C]\\\-\-tcti:bus_type=session\f[]
.PP
\f[B]NOTE\f[]: abrmd and tabrmd are synonymous.
the various known TCTI modules.
# EXAMPLES
.RE
.SS Create a primary object and read the public structure in an openssl
compliant format
.IP
.nf
\f[C]
tpm2_createprimary\ \-c\ primary.ctx
tpm2_readpublic\ \-c\ primary.ctx\ \-o\ output.dat\ \-f\ pem
\f[]
.fi
.SS Serialize an existing persistent object handle to disk for later use
.PP
This work\-flow is primarily intended for existing persistent TPM
objects.
This work\-flow does not verify that the name of the serialized object
matches the expected, and thus the serialized handle could be pointing
to an attacker controlled object if no verification is done.
If you are creating an object from scratch, save the serialized handle
when making the object persistent.
.PP
We assume that an object has already been persisted, for example via:
.IP
.nf
\f[C]
#\ We\ assume\ that\ an\ object\ has\ already\ been\ persisted,\ for\ example
tpm2_createprimary\ \-c\ primary.ctx

#\ context\ files\ have\ all\ the\ information\ for\ the\ TPM\ to\ verify\ the\ object
tpm2_evictcontrol\ \-c\ primary.ctx
persistent\-handle:\ 0x81000001
action:\ persisted
\f[]
.fi
.PP
Next use the persistent handle to get a serialized handle:
.IP
.nf
\f[C]
#\ The\ persistent\ handle\ output\ could\ be\ at\ an\ attacker\ controlled\ object,
#\ best\ practice\ is\ to\ use\ the\ option\ "\-o:\ for\ tpm2_evictcontrol\ to\ get\ a
#\ serialized\ handle\ instead.

tpm2_readpublic\ \-c\ 0x81000001\ \-o\ output.dat\ \-f\ pem\ \-t\ primary.handle

#\ use\ this\ verified\ handle\ in\ an\ encrypted\ session\ with\ the\ tpm
tpm2_startauthsession\ \-\-policy\-session\ \-S\ session.ctx\ \-c\ primary.handle
\f[]
.fi
.PP
For new objects, its best to use all serialized handles.
.SH Returns
.PP
Tools can return any of the following codes:
.IP \[bu] 2
0 \- Success.
.IP \[bu] 2
1 \- General non\-specific error.
.IP \[bu] 2
2 \- Options handling error.
.IP \[bu] 2
3 \- Authentication error.
.IP \[bu] 2
4 \- TCTI related error.
.IP \[bu] 2
5 \- Non supported scheme.
Applicable to tpm2_testparams.
.SH BUGS
.PP
Github Issues (https://github.com/tpm2-software/tpm2-tools/issues)
.SH HELP
.PP
See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)