tpm2_hmac

Section: General Commands Manual (1)
Updated: SEPTEMBER 2017
Page Index

NAME

tpm2_hmac(1) - Performs an HMAC operation with the TPM.

SYNOPSIS

tpm2_hmac [OPTIONS] FILE

DESCRIPTION

tpm2_hmac(1) - performs an HMAC operation on FILE and returns the results. If FILE is not specified, then data is read from stdin.

OPTIONS

•: -k, -key-handle=KEY_CONTEXT_FILE: The key handle for the symmetric signing key providing the HMAC key.
•: -c, -key-context=KEY_CONTEXT_FILE: The filename of the key context used for the operation.
•: -P, -pwdk=KEY_PASSWORD: The password for key, optional. Passwords should follow the "password formatting standards, see section"Password Formatting“.
•: -g, -halg=HASH_ALGORITHM: The hash algorithm to use. Algorithms should follow the "formatting standards, see section"Algorithm Specifiers". Also, see section"Supported Hash Algorithms" for a list of supported hash algorithms.
•: -o, -outfile=OUT_FILE Optional file record of the HMAC result. Defaults to stdout.
•: -S, -input-session-handle=SESSION_HANDLE: Optional Input session handle from a policy session for authorization.

COMMON OPTIONS

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

•: -h, -help: Display the tools manpage. This 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. # TCTI ENVIRONMENT

This collection of environment variables that may be used to configure the various TCTI modules available.

The values passed through these variables can be overridden on a per-command basis using the available command line options, see the TCTI_OPTIONS section.

The variables respected depend on how the software was configured.

•

TPM2TOOLS_TCTI_NAME: Select the TCTI used for communication with the next component down the TSS stack. In most configurations this will be the TPM but it could be a simulator or proxy. The current known TCTIs are:

•: tabrmd - The new resource manager, called tabrmd (https://github.com/01org/tpm2-abrmd).
•: socket - Typically used with the old resource manager, or talking directly to a simulator.
•: device - Used when talking directly to a TPM device file.

•

TPM2TOOLS_DEVICE_FILE: When using the device TCTI, specify the TPM device file. The default is "/dev/tpm0".

: Note: Using the tpm directly requires the users to ensure that concurrent access does not occur and that they manage the tpm resources. These tasks are usually managed by a resource manager. Linux 4.12 and greater supports an in kernel resource manager at "/dev/tpmrm", typically "/dev/tpmrm0".

•

TPM2TOOLS_SOCKET_ADDRESS: When using the socket TCTI, specify the domain name or IP address used. The default is 127.0.0.1.

•

TPM2TOOLS_SOCKET_PORT: When using the socket TCTI, specify the port number used. The default is 2321.

TCTI OPTIONS

This collection of options are used to configure the varous TCTI modules available. They override any environment variables.

•

-T, -tcti=TCTI_NAME[:TCTI_OPTIONS]: Select the TCTI used for communication with the next component down the TSS stack. In most configurations this will be the resource manager: tabrmd (https://github.com/01org/tpm2-abrmd) Optionally, tcti specific options can appended to TCTI_NAME by appending a : to TCTI_NAME.

•: For the device TCTI, the TPM device file for use by the device TCTI can be specified. The default is /dev/tpm0. Example: -T device:/dev/tpm0
•: For the socket TCTI, the domain name or IP address and port number used by the socket can be specified. The default are 127.0.0.1 and 2321. Example: -T socket:127.0.0.1:2321
•: For the abrmd TCTI, it takes no options. Example: -T abrmd

Password Formatting

Passwords are interpreted in two forms, string and hex-string. A string password is not interpreted, and is directly used for authorization. A hex-string, is converted from a hexidecimal form into a byte array form, thus allowing passwords with non-printable and/or terminal un-friendly characters.

By default passwords are assumed to be in the string form. Password form is specified with special prefix values, they are:

•: str: - Used to indicate it is a raw string. Useful for escaping a password that starts with the "hex:" prefix.
•: hex: - Used when specifying a password in hex string format.

Supported Hash Algorithms

Supported hash algorithms are:

•: 0x4 or sha1 for TPM_ALG_SHA1 (default)
•: 0xB or sha256 for TPM_ALG_SHA256
•: 0xC or sha384 for TPM_ALG_SHA384
•: 0xD or sha512 for TPM_ALG_SHA512
•: 0x12 or sm3_256 for TPM_ALG_SM3_256

NOTE: Your TPM may not support all algorithms.

Algorithm Specfiers

Options that take algorithms support "nice-names". Nice names, like sha1 can be used in place of the raw hex for sha1: 0x4. The nice names are converted by stripping the leading TPM_ALG_ from the Algorithm Name field and converting it to lower case. For instance TPM_ALG_SHA3_256 becomes sha3_256.

The algorithms can be found at: <https://trustedcomputinggroup.org/wp-content/uploads/TCG_Algorithm_Registry_Rev_1.24.pdf>

EXAMPLES

Perform a SHA1 HMAC on data.in and send output and possibly ticket to stdout:


tpm2_hmac -k 0x81010002 -P abc123 -g sha1 data.in

Perform a SHA1 HMAC on data.in read as a file to stdin and send output to a file:


tpm2_hmac -c key.context -P abc123 -g sha1 -o hash.out << data.in

Perform a SHA256 HMAC on stdin and send result and possibly ticket to stdout:

cat data.in | tpm2_hmac -k 0x81010002 -g sha256 -o hash.out ```

RETURNS

0 on success or 1 on failure.

BUGS

Github Issues (https://github.com/01org/tpm2-tools/issues)

HELP

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