Provided by: tpm2-tools_5.4-1_amd64 bug

NAME

       tpm2_policysecret(1)  -  Couples  the  authorization  of  an object to that of an existing
       object.

SYNOPSIS

       tpm2_policysecret [OPTIONS] [ARGUMENT]

DESCRIPTION

       tpm2_policysecret(1) - Couples the authorization of an  object  to  that  of  an  existing
       object without requiring exposing the existing secret until time of object use.

OPTIONS

-c, --object-context=OBJECT:

         A  context  object  specifier of a transient/permanent/persistent object.  Either a file
         path of a object context blob or a loaded/persistent/permanent handle id.   See  section
         “Context  Object Format”.  As an argument, it takes the auth value of the associated TPM
         object, a single dash - can be used to read the auth value  from  stdin.   The  argument
         follows   the   “authorization   formatting   standards”,   see  section  “Authorization
         Formatting”.

       • -S, --session=FILE:

         The policy session file generated via the -S option to tpm2_startauthsession(1).

       • -L, --policy=FILE:

         File to save the policy digest.

       • -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 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.

       • -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.

       • -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.

       • --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 to be used in an audit or a policycphash.

       • ARGUMENT the command line argument specifies the AUTH to be set for the object specified
         with -c.

   References

Context Object Format

       The type of a context object, whether it is a handle or file name, is determined according
       to the following logic in-order:

       • If the argument is a file path, then the file is loaded  as  a  restored  TPM  transient
         object.

       • If the argument is a prefix match on one of:

         • owner: the owner hierarchy

         • platform: the platform hierarchy

         • endorsement: the endorsement hierarchy

         • lockout: the lockout control persistent object

       • If  the  argument  argument  can  be  loaded  as  a number it will be treat as a handle,
         e.g. 0x81010013 and used directly._OBJECT_.

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:1122334455667788

   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 argument that contains the output of the raw PCR contents
       as returned by tpm2_pcrread(1).

       PCR bank specifiers

   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.

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

       Associate auth value of a sealing object to the owner hierarchy password.  * Start a trial
       auth session and run tpm2_policysecret(1) to create policy that can only be  satisfied  if
       owner  hierarchy  auth  value  is supplied.  * Start a real policy session and provide the
       owner hierarchy auth value.  * Provide the session input where  in  the  policysecret  for
       owner  hierarchy  auth  was  satisfied  to the unseal tool.  * If the policy was satisfied
       unsealing should succeed.

   Generate a policy that binds to the secret of the owner hiearchy
              tpm2_startauthsession -S session.ctx

              tpm2_policysecret -S session.ctx -c o -L secret.policy

              tpm2_flushcontext session.ctx

   Create a TPM object using the policy
              tpm2_createprimary -Q -C o -g sha256 -G rsa -c prim.ctx

              tpm2_create -Q -g sha256 -u sealing_key.pub -r sealing_key.priv -i- \
                -C prim.ctx -L secret.policy <<< "SEALED-SECRET"

              tpm2_load -C prim.ctx -u sealing_key.pub -r sealing_key.priv \
                -c sealing_key.ctx

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

              tpm2_policysecret -S session.ctx -c o -L secret.policy

              tpm2_unseal -p "session:session.ctx" -c sealing_key.ctx
              SEALED-SECRET

              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.linuxfoundation.org/mailman/listinfo/tpm2)