Provided by: tpm2-tools_5.2-1build1_amd64 
NAME
tpm2_makecredential(1) - Generate the encrypted-user-chosen-data and the wrapped-secret-
data-encryption-key for the privacy-sensitive credentialing process of a TPM object.
SYNOPSIS
tpm2_makecredential [OPTIONS]
DESCRIPTION
tpm2_makecredential(1) - The TPM supports a privacy preserving protocol for distributing
credentials for keys on a TPM. The process guarantees that the credentialed-TPM-
object(AIK) is loaded on the same TPM as a well-known public-key-object(EK) without
knowledge of the specific public properties of the credentialed-TPM-object(AIK). The
privacy is guaranteed due to the fact that only the name of the credentialed-TPM-
object(AIK) is shared and not the credentialed-TPM-object’s public key itself.
Make-credential is the first step in this process where in after receiving the public-key-
object(EK) public key of the TPM and the name of the credentialed-TPM-object(AIK), an
encrypted-user-chosen-data is generated and the secret-data-encryption-key is generated
and wrapped using cryptographic processes specific to credential activation that
guarantees that the credentialed-TPM-object(AIK) is loaded on the TPM with the well-known
public-key-object(EK).
tpm2_makecredential can be used to generate the encrypted-user-chosen-data and the wrapped
secret-data-encryption-key without a TPM by using the none TCTI option.
OPTIONS
• -e, --encryption-key=FILE:
DEPRECATED, use -u or –public instead.
• -u, --public=FILE:
A TPM public key which was used to wrap the seed. NOTE: This option is same as -e and
is added to make it similar with other tools specifying the public key. The old option
is retained for backwards compatibility.
• -G, --key-algorithm=ALGORITHM:
The key algorithm associated with TPM public key. Specify either RSA/ ECC. When this
option is used, input public key is expected to be in PEM format and the default TCG EK
template is used for the key properties.
• -s, --secret=FILE or STDIN:
The secret which will be protected by the key derived from the random seed. It can be
specified as a file or passed from stdin.
• -n, --name=FILE:
The name of the key for which certificate is to be created.
• -o, --credential-blob=FILE:
The output file path, recording the encrypted-user-chosen-data and the wrapped secret-
data-encryption-key.
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.
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.
EXAMPLES
tpm2 createek -Q -c 0x81010009 -G rsa -u ek.pub
tpm2 createak -C 0x81010009 -c ak.ctx -G rsa -g sha256 -s rsassa -u ak.pub \
-n ak.name -p akpass> ak.out
file_size=`ls -l ak.name | awk {'print $5'}`
loaded_key_name=`cat ak.name | xxd -p -c $file_size`
tpm2 readpublic -c 0x81010009 -o ek.pem -f pem -Q
echo "12345678" | tpm2 makecredential -Q -u ek.pem -s - -n $loaded_key_name \
-o mkcred.out -G rsa
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)