Ubuntu Manpage: tpm2_create(1) - Create a child object.

Provided by: tpm2-tools_4.1.1-1ubuntu0.20.04.1_amd64

NAME

       tpm2_create(1) - Create a child object.

SYNOPSIS

       tpm2_create [OPTIONS]

DESCRIPTION

       tpm2_create(1)  -  Create a child object.  The object can either be a key or a sealing object.  A sealing
       object allows to seal user data to the TPM, with a maximum size of 256 bytes.  Additionally it will  load
       the created object if the -o is specified.

OPTIONS

These options for creating the TPM entity:

• -C, --parent-context=OBJECT:

The parent of the object to be created.

• -P, --parent-auth=AUTH:

The authorization value of the parent object specified with -C.

• -p, --key-auth=AUTH:

The authorization value for the created object.

• -g, --hash-algorithm=ALGORITHM:

The hash algorithm for generating the objects name. This is optional and defaults to sha256 when not
specified.

• -G, --key-algorithm=ALGORITHM:

The key algorithm associated with this object. It defaults to “rsa” if not specified.

• -a, --attributes=ATTRIBUTES:

The object attributes, optional. The default for created objects is:

When -i is specified for sealing, TPMA_OBJECT_SIGN_ENCRYPT and TPMA_OBJECT_DECRYPT are removed from the
default attribute set. The algorithm is set in a way where the the object is only good for sealing and
unsealing. I.e. one cannot use an object for sealing and cryptography operations.

• -i, --sealing-input=FILE or STDIN:

The data file to be sealed, optional. If file is -, read from stdin. When sealing data only the
TPM_ALG_KEYEDHASH algorithm with a NULL scheme is allowed. Thus, -G cannot be specified.

• -L, --policy=FILE:

The input policy file, optional.

• -u, --public=FILE:

The output file which contains the public portion of the created object, optional.

• -r, --private=FILE:

The output file which contains the sensitive portion of the object, optional.

• -c, --key-context=FILE:

The output file which contains the key context, optional. The key context is analogous to the context
file produced by tpm2_load(1), however is generated via a tpm2_createloaded(1) command. This option
can be used to avoid the normal tpm2_create(1) and tpm2_load(1) command sequences and do it all in one
command, atomically.

• --creation-data=FILE:

An optional file output that saves the creation data for certification.

• --template-data=FILE:

An optional file output that saves the key template data (TPM2B_PUBLIC) to be used in
tpm2_policytemplate.

• -t, --creation-ticket=FILE:

An optional file output that saves the creation ticket for certification.

• -d, --creation-hash=FILE:

An optional file output that saves the creation hash for certification.

• -q, --outside-info=HEX_STR_OR_FILE:

An optional hex string or path to add unique data to the creation data. Note that it does not
contribute in creating statistically unique object.

• -l, --pcr-list=PCR:

The list of PCR banks and selected PCRs’ ids for each bank to be included in the creation data for
certification.

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: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.

Algorithm Specifiers

Options that take algorithms support “nice-names”.

There are two major algorithm specification string classes, simple and complex. Only certain algorithms
will be accepted by the TPM, based on usage and conditions.

Simple specifiers
These are strings with no additional specification data. When creating objects, non-specified portions
of an object are assumed to defaults. You can find the list of known “Simple Specifiers Below”.

Asymmetric
• rsa

• ecc

Symmetric
• aes

• camellia

Hashing Algorithms
• sha1

• sha256

• sha384

• sha512

• sm3_256

• sha3_256

• sha3_384

• sha3_512

Keyed Hash
• hmac

• xor

Signing Schemes
• rsassa

• rsapss

• ecdsa

• ecdaa

• ecschnorr

Asymmetric Encryption Schemes
• oaep

• rsaes

• ecdh

Modes
• ctr

• ofb

• cbc

• cfb

• ecb

Misc
• null

Complex Specifiers
Objects, when specified for creation by the TPM, have numerous algorithms to populate in the public data.
Things like type, scheme and asymmetric details, key size, etc. Below is the general format for
specifying this data: <type>:<scheme>:<symmetric-details>

Type Specifiers
This portion of the complex algorithm specifier is required. The remaining scheme and symmetric details
will default based on the type specified and the type of the object being created.

• aes - Default AES: aes128

• aes128<mode> - 128 bit AES with optional mode (ctr|ofb|cbc|cfb|ecb). If mode is not specified,
defaults to null.

• aes192<mode> - Same as aes128<mode>, except for a 192 bit key size.

• aes256<mode> - Same as aes128<mode>, except for a 256 bit key size.

• ecc - Elliptical Curve, defaults to ecc256.

• ecc192 - 192 bit ECC

• ecc224 - 224 bit ECC

• ecc256 - 256 bit ECC

• ecc384 - 384 bit ECC

• ecc521 - 521 bit ECC

• rsa - Default RSA: rsa2048

• rsa1024 - RSA with 1024 bit keysize.

• rsa2048 - RSA with 2048 bit keysize.

• rsa4096 - RSA with 4096 bit keysize.

Scheme Specifiers
Next, is an optional field, it can be skipped.

Schemes are usually Signing Schemes or Asymmetric Encryption Schemes. Most signing schemes take a hash
algorithm directly following the signing scheme. If the hash algorithm is missing, it defaults to
sha256. Some take no arguments, and some take multiple arguments.

Hash Optional Scheme Specifiers
These scheme specifiers are followed by a dash and a valid hash algorithm, For example: oaep-sha256.

• oaep

• ecdh

• rsassa

• rsapss

• ecdsa

• ecschnorr

Multiple Option Scheme Specifiers
This scheme specifier is followed by a count (max size UINT16) then folloed by a dash(-) and a valid hash
algorithm. * ecdaa For example, ecdaa4-sha256. If no count is specified, it defaults to 4.

No Option Scheme Specifiers
This scheme specifier takes NO arguments. * rsaes

Symmetric Details Specifiers
This field is optional, and defaults based on the type of object being created and it’s attributes.
Generally, any valid Symmetric specifier from the Type Specifiers list should work. If not specified, an
asymmetric objects symmetric details defaults to aes128cfb.

Examples
Create an rsa2048 key with an rsaes asymmetric encryption scheme
tpm2_create -C parent.ctx -G rsa2048:rsaes -u key.pub -r key.priv

Create an ecc256 key with an ecdaa signing scheme with a count of 4 and sha384 hash
/tpm2_create -C parent.ctx -G ecc256:ecdaa4-sha384 -u key.pub -r key.priv cryptographic algorithms
ALGORITHM.

Object Attributes

       Object  Attributes  are  used  to  control  various  properties of created objects.  When specified as an
       option, either the raw bitfield mask or “nice-names” may be used.  The values can be found  in  Table  31
       Part 2 of the TPM2.0 specification, which can be found here:

       <https://trustedcomputinggroup.org/wp-content/uploads/TPM-Rev-2.0-Part-2-Structures-01.38.pdf>

       Nice  names  are calculated by taking the name field of table 31 and removing the prefix TPMA_OBJECT_ and
       lowercasing the result.  Thus, TPMA_OBJECT_FIXEDTPM becomes fixedtpm.  Nice names can be joined using the
       bitwise or “|” symbol.

       For instance, to set The fields TPMA_OBJECT_FIXEDTPM, TPMA_OBJECT_NODA, and TPMA_OBJECT_SIGN_ENCRYPT, the
       argument would be:

       fixedtpm|noda|sign specifying the object attributes ATTRIBUTES.

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

   Setup
       In order to create an object, we must first create a primary key as it’s parent.

              tpm2_createprimary -c primary.ctx

   Create an Object
       This will create an object using all the default values and store  the  TPM  sealed  private  and  public
       portions to the paths specified via -u and -r respectively.  The tool defaults to an RSA key.

              tpm2_create -C primary.ctx -u obj.pub -r obj.priv

   Seal Data to the TPM
       Outside of key objects, the TPM allows for small amounts of user specified data to be sealed to the TPM.

              echo "my sealed data" > seal.dat
              tpm2_create -C primary.ctx -i seal.dat -u obj.pub -r obj.priv

   Create an EC Key Object and Load it to the TPM
       Normally,  when  creating  an object, only the public and private portions of the object are returned and
       the caller needs to use tpm2_load(1) to load those public and private portions to the  TPM  before  being
       able to use the object.  However, this can be accomplished within this command as well.

              tpm2_create -C primary.ctx -G ecc -u obj.pub -r obj.priv -c ecc.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.

BUGS

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

HELP

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