NAME

       tpm2_policysigned(1)  -  Enables  policy  authorization by verifying signature of optional
       TPM2 parameters.  The signature is generated by a signing authority.

SYNOPSIS

       tpm2_policysigned [OPTIONS]

DESCRIPTION

       tpm2_policysigned(1) - Enables policy authorization by  verifying  signature  of  optional
       TPM2  parameters.   The  signature is generated by a signing authority.  The optional TPM2
       parameters being cpHashA, nonceTPM, policyRef and expiration.

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_startauthsession(1).

       • -c, --key-context=OBJECT:

         Context object for the key context used for the operation.  Either a file  or  a  handle
         number.  See section “Context Object Format”.

       • -g, --hash-algorithm=ALGORITHM:

         The hash algorithm used to digest the message.

       • -s, --signature=FILE:

         The input signature file of the signature to be validated.

       • -f, --format=FORMAT:

         Set  the  input  signature  file  to  a  specified  format.   The  default is the tpm2.0
         TPMT_SIGNATURE data format, however different schemes can be selected if the  data  came
         from an external source like OpenSSL.  The tool currently supports rsassa and ecdsa.

       • -t, --expiration=NATURAL_NUMBER:

         Set the expiration time of the policy in seconds.  In absence of nonceTPM the expiration
         time is the policy timeout value.  If expiration is a negative  value  an  authorization
         ticket is additionally returned.  If expiration value is 0 then the policy does not have
         a time limit on the authorization.

       • --ticket=FILE:

         The ticket file to record the authorization ticket structure.

       • --timeout=FILE:

         The file path to record the timeout structure returned.

       • -q, --qualification=FILE_OR_HEX_STR:

         Optional, the policy qualifier data that  the  signer  can  choose  to  include  in  the
         signature.  Can be either a hex string or path.

       • -x, --nonce-tpm:

         Enable  the  comparison  of the current session’s nonceTPM to ensure the validity of the
         policy authorization is limited to the current session.

   References

COMMON OPTIONS

       This collection of options are common to many programs and provide information  that  many
       users may expect.

       • -h,  --help=[man|no-man]:  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.

         To  successfully  use  the  manpages feature requires the manpages to be installed 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 console  during  its
         execution.  When using this option the file and line number 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.   Defining   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 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

       Authorize  a  TPM  operation on an object whose authorization is bound to specific signing
       authority.

   Create the signing authority
              openssl genrsa -out private.pem 2048

              openssl rsa -in private.pem -outform PEM -pubout -out public.pem

   Generate signature with nonceTPM, cpHashA, policyRef and expiration set to 0
              echo "00 00 00 00" | xxd -r -p | \
              openssl dgst -sha256 -sign private.pem -out signature.dat

   Load the verification key and Create the policysigned policy
              tpm2_loadexternal -C o -G rsa -u public.pem -c signing_key.ctx

              tpm2_startauthsession -S session.ctx

              tpm2_policysigned -S session.ctx -g sha256 -s signature.dat -f rsassa \
              -c signing_key.ctx -L policy.signed

              tpm2_flushcontext session.ctx

   Create a sealing object to use the policysigned
              echo "plaintext" > secret.data

              tpm2_createprimary -C o -c prim.ctx

              tpm2_create -u key.pub -r sealing_key.priv -c sealing_key.ctx -C prim.ctx \
              -i secret.data -L policy.signed

   Satisfy the policy and unseal secret
              tpm2_startauthsession -S session.ctx --policy-session

              tpm2_policysigned -S session.ctx -g sha256 -s signature.dat -f rsassa \
              -c signing_key.ctx -L policy.signed

              tpm2_unseal -p session:session.ctx -c sealing_key.ctx

              tpm2_flushcontext session.ctx

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)