tpm2_changeauth man page
tpm2_changeauth — Changes authorization values for TPM objects. tpm2_changeauth - Configures authorization values for the various hierarchies, NV indices, transient and persistent objects. Note: For non-permanent objects (Transient objects and Persistent objects), copies of the private information (files or persistent handles) created prior to changing auth are not invalidated. Passwords should follow the "password authorization formatting standards", see section "Authorization Formatting". -c, --object-context=OBJECT: The key context object to be used for the operation. -p, --object-auth=AUTH: The old authorization value for the TPM object specified with -c. -C, --parent-context=OBJECT: The parent object. This is required if the object for the operation is a transient or persistent object. 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 prefix match on one of: 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 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. A string password, specified by prefix "str:" or it's absence (raw string without prefix) is not interpreted, and is directly used for authorization. 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. 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. 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. To use a session context file called session.ctx. To use a session context file called session.ctx AND send the authvalue mypassword. To use a session context file called session.ctx AND send the HEX authvalue 0x11223344. You can satisfy a PCR policy using the "pcr:" prefix and the PCR minilanguage. The PCR minilanguage is as follows: The PCR spec is documented in in the section "PCR bank specifiers". The PCR bank specifiers (common/pcr.md) To satisfy a PCR policy of sha256 on banks 0, 1, 2 and 3 use a specifier of: specifying AUTH. 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. 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: Note: The command line option always overrides the environment variable. The current known TCTIs are: The arguments to either the command line option or the environment variable are in the form: Specifying an empty string for either the 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. 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. 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: Specify the tabrmd tcti name and a config string of Specify the default (abrmd) tcti and a config string of NOTE: abrmd and tabrmd are synonymous. the various known TCTI modules. Tools can return any of the following codes: Github Issues (https://github.com/tpm2-software/tpm2-tools/issues) See the Mailing List (https://lists.01.org/mailman/listinfo/tpm2)Synopsis
tpm2_changeauth [Options] [ARGUMENT]Description
Options
References
Context Object Format
Authorization Formatting
Passwords
String
Examples
foobar
str:foobarHex-string
Example
hex:0x1122334455667788File
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:- <<< foobarSessions
Examples
session:session.ctxsession:session.ctx+mypasswordsession:session.ctx+hex:11223344PCR Authorizations
<pcr-spec>=<raw-pcr-file>raw-pcr-file is an optional the output of the raw PCR contents as returned by tpm2_pcrread(1).Examples
pcr:sha256:0,1,2,3Common Options
TCTI Configuration
<tcti-name>:<tcti-option-config><tcti-name> or <tcti-option-config> results in the default being used for that portion respectively.TCTI Defaults
Custom TCTIs
Tcti Options
bus_name=com.example.FooBar:\--tcti=tabrmd:bus_name=com.example.FooBarbus_type=session:\--tcti:bus_type=sessionExamples
Returns
Bugs
Help
Info