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)