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tpm2_policypassword(1)	     General Commands Manual	  tpm2_policypassword(1)

NAME
     tpm2_policypassword(1)  -	Enables  binding  a  policy to the authorization
     value of the authorized TPM object.

SYNOPSIS
     tpm2_policypassword [OPTIONS]

DESCRIPTION
     tpm2_policypassword(1) - Enables a policy that requires  the  object's  au-
     thentication  passphrase be provided.  This is equivalent to authenticating
     using the object passphrase in plaintext, only this enforces it as  a  pol-
     icy.   It provides a mechanism to allow for password authentication when an
     object only allows policy based authorization, ie object  attribute  "user-
     withauth" is 0.

OPTIONS
     * -L, --policy=FILE:

       File to save the compounded policy digest.

     * -S, --session=FILE:

       The policy session file generated via the -S option to tpm2_startauthses-
       sion(1).

     * --cphash=FILE

       File path to record the hash of the command parameters.	This is commonly
       termed  as cpHash.  NOTE: When this option is selected, The tool will not
       actually execute the command, it simply returns a cpHash.

   References
COMMON OPTIONS
     This collection of options are common to many programs and provide informa-
     tion that many users may expect.

     * -h, --help=[man|no-man]: Display the tools manpage.  By default,  it  at-
       tempts to invoke the manpager for the tool, however, on failure will out-
       put  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 speci-
       fied, or the manpager fails, the short options will be output to stdout.

       To  successfully use the manpages feature requires the manpages to be in-
       stalled or on MANPATH, See man(1) for more details.

     * -v, --version: Display version information for this tool, supported tctis
       and exit.

     * -V, --verbose: Increase the information that the tool prints to the  con-
       sole during its execution.  When using this option the file and line num-
       ber are printed.

     * -Q, --quiet: Silence normal tool output to stdout.

     * -Z,  --enable-errata: Enable the application of errata fixups.  Useful if
       an errata fixup needs to be applied to commands sent to the TPM.   Defin-
       ing  the  environment TPM2TOOLS_ENABLE_ERRATA is equivalent.  information
       many users may expect.

TCTI Configuration
     The TCTI or "Transmission Interface" is the  communication  mechanism  with
     the TPM.  TCTIs can be changed for communication with TPMs across different
     mediums.

     To control the TCTI, the tools respect:

     1. The command line option -T or --tcti

     2. The environment variable: TPM2TOOLS_TCTI.

     Note: The command line option always overrides the environment variable.

     The current known TCTIs are:

     * tabrmd	   -	  The	   resource	 manager,      called	  tabrmd
       (https://github.com/tpm2-software/tpm2-abrmd).	Note  that  tabrmd   and
       abrmd as a tcti name are synonymous.

     * mssim - Typically used for communicating to the TPM software simulator.

     * device - Used when talking directly to a TPM device file.

     * 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 connec-
       tion.  Does not support ANY options and MUST BE presented  as  the  exact
       text of "none".

     The arguments to either the command line option or the environment variable
     are in the form:

     <tcti-name>:<tcti-option-config>

     Specifying  an empty string for either the <tcti-name> or <tcti-option-con-
     fig> results in the default being used for that portion respectively.

   TCTI Defaults
     When a TCTI is not specified,  the  default  TCTI	is  searched  for  using
     dlopen(3)	semantics.   The  tools will search for tabrmd, device and mssim
     TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND.  You can query  what  TCTI
     will  be  chosen as the default by using the -v option to print the version
     information.  The "default-tcti" key-value pair will indicate which of  the
     aforementioned TCTIs is the default.

   Custom TCTIs
     Any  TCTI	that  implements  the dynamic TCTI interface can be loaded.  The
     tools internally use dlopen(3), and the raw tcti-name value is used for the
     lookup.  Thus, this could be a path to the shared	library,  or  a  library
     name as understood by dlopen(3) semantics.

TCTI OPTIONS
     This  collection  of  options  are used to configure the various known TCTI
     modules available:

     * device: For the device TCTI, the TPM character device file for use by the
       device TCTI can be specified.  The default is /dev/tpm0.

       Example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI="device:/dev/tpm0"

     * mssim: 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.

       Example:      -T      mssim:host=localhost,port=2321	 or	  export
       TPM2TOOLS_TCTI="mssim:host=localhost,port=2321"

     * abrmd: For the abrmd TCTI, the configuration string format is a series of
       simple  key value pairs separated by a `,' character.  Each key and value
       string are separated by a `=' character.

       * TCTI abrmd supports two keys:

	 1. `bus_name' : The name of the tabrmd service on the bus (a string).

	 2. `bus_type' : The type of the dbus instance	(a  string)  limited  to
	    `session' and `system'.

       Specify	the  tabrmd  tcti name and a config string of bus_name=com.exam-
       ple.FooBar:

	      \--tcti=tabrmd:bus_name=com.example.FooBar

       Specify the default (abrmd) tcti and a config string of bus_type=session:

	      \--tcti:bus_type=session

       NOTE: abrmd and tabrmd are synonymous.  the various known TCTI modules.

EXAMPLES
     We want to authenticate using  the  TPM  objects  plaintext  authentication
     value.   While we could authenticate with an ephemeral password session, in
     this example we will authenticate with the plaintext passphrase in a policy
     session instead using the tpm2_policypassword(1) tool.

   Create the password policy
	    tpm2_startauthsession -S session.dat

	    tpm2_policypassword -S session.dat -L policy.dat

	    tpm2_flushcontext session.dat

   Create the object with a passphrase and the password policy
	    tpm2_createprimary -C o -c prim.ctx

	    tpm2_create -g sha256 -G aes -u key.pub -r key.priv -C prim.ctx -L policy.dat \
	      -p testpswd

   Authenticate with plaintext passphrase input
	    tpm2_load -C prim.ctx -u key.pub -r key.priv -n key.name -c key.ctx

	    echo "plaintext" > plain.txt
	    tpm2_encryptdecrypt -c key.ctx -o encrypt.out plain.txt -p testpswd plain.txt

   Authenticate with password and the policy
	    tpm2_startauthsession \--policy-session -S session.dat

	    tpm2_policypassword -S session.dat -L policy.dat

	    tpm2_encryptdecrypt -c key.ctx -o encrypt.out \
	      -p session:session.dat+testpswd plain.txt

	    tpm2_flushcontext session.dat

Returns
     Tools can return any of the following codes:

     * 0 - Success.

     * 1 - General non-specific error.

     * 2 - Options handling error.

     * 3 - Authentication error.

     * 4 - TCTI related error.

     * 5 - Non supported scheme.  Applicable to tpm2_testparams.

Limitations
     It expects a session to be already established via tpm2_startauthsession(1)
     and requires one of the following:

     * direct device access

     * extended session support with tpm2-abrmd.

     Without it, most resource managers will not save session state between com-
     mand invocations.

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

HELP
     See    the    Mailing     List	(https://lists.linuxfoundation.org/mail-
     man/listinfo/tpm2)

tpm2-tools						  tpm2_policypassword(1)

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