NAME

       tpm2_changepps(1) - Replaces the active platform primary seed with a new one generated off the TPM2 RNG.

SYNOPSIS

       tpm2_changepps [OPTIONS]

DESCRIPTION

       tpm2_changepps(1)  - Replaces the active platform primary seed with a new one generated off the TPM2 RNG.
       The Transient and Persistent objects under the platform  hierarchy  are  lost  whilst  retaining  the  NV
       objects.

OPTIONS

       • -p, --auth specifies the AUTH for the platform.  hierarchy.

   References

Authorization Formatting

       Authorization  for  use  of  an  object in TPM2.0 can come in 3 different forms: 1.  Password 2.  HMAC 3.
       Sessions

       NOTE: “Authorizations default to the EMPTY PASSWORD when not specified”.

   Passwords
       Passwords are interpreted in the following forms below using prefix identifiers.

       Note: By default passwords are assumed to be in the string form when they do not have a prefix.

   String
       A string password, specified by prefix “str:”  or  it’s  absence  (raw  string  without  prefix)  is  not
       interpreted, and is directly used for authorization.

   Examples
              foobar
              str:foobar

   Hex-string
       A  hex-string password, specified by prefix “hex:” is converted from a hexidecimal form into a byte array
       form, thus allowing passwords with non-printable and/or terminal un-friendly characters.

   Example
              hex:0x1122334455667788

   File
       A file based password, specified be prefix “file:” should be the path of a file containing  the  password
       to  be  read by the tool or a “-” to use stdin.  Storing passwords in files prevents information leakage,
       passwords passed as options can be read from the process list or common shell history features.

   Examples
              # to use stdin and be prompted
              file:-

              # to use a file from a path
              file:path/to/password/file

              # to echo a password via stdin:
              echo foobar | tpm2_tool -p file:-

              # to use a bash here-string via stdin:

              tpm2_tool -p file:- <<< foobar

   Sessions
       When using a policy session to authorize the use of an  object,  prefix  the  option  argument  with  the
       session  keyword.  Then indicate a path to a session file that was created with tpm2_startauthsession(1).
       Optionally, if the session requires an auth  value  to  be  sent  with  the  session  handle  (eg  policy
       password), then append a + and a string as described in the Passwords section.

   Examples
       To use a session context file called session.ctx.

              session:session.ctx

       To use a session context file called session.ctx AND send the authvalue mypassword.

              session:session.ctx+mypassword

       To use a session context file called session.ctx AND send the HEX authvalue 0x11223344.

              session:session.ctx+hex:11223344

   PCR Authorizations
       You  can  satisfy a PCR policy using the “pcr:” prefix and the PCR minilanguage.  The PCR minilanguage is
       as follows: <pcr-spec>=<raw-pcr-file>

       The PCR spec is documented in in the section “PCR bank specifiers”.

       The raw-pcr-file is an optional the output of the raw PCR contents as returned by tpm2_pcrread(1).

       PCR bank specifiers (common/pcr.md)

   Examples
       To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifier of:

              pcr:sha256:0,1,2,3

       specifying AUTH.

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 connection.  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-config>  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.example.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

   Change the platform primary seed where the platform auth is NULL.
              tpm2_changepps

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 command invocations.

BUGS

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

HELP

       See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)