man
1 tpm2_pcrread
tpm2_pcrread(1) General Commands Manual tpm2_pcrread(1)
NAME
tpm2_pcrread(1) - List PCR values.
SYNOPSIS
tpm2_pcrread [OPTIONS] PCR_LIST_OR_ALG
DESCRIPTION
tpm2_pcrread(1) - Displays PCR values. Without any arguments,
tpm2_pcrread(1) outputs all PCRs and their hash banks. One can use
specify the hash algorithm or a pcr list as an argument to filter the
output.
To only output PCR banks with a given algorithm, specify the hashing
algorithm as the argument. Algorithms should follow the "formatting
standards", see section "Algorithm Specifiers". Also, see section
"Supported Hash Algorithms" for a list of supported hash algorithms.
To output a list of PCR banks (sha1, sha256, etc) and ids (0, 1, 2 etc)
specify a PCR selection list as the argument as specified via section
"PCR Bank Specifiers".
Also read NOTES section below.
Output is written in a YAML format to stdout, with each algorithm fol-
lowed by a PCR index and its value. As a simple example assume just
sha1 and sha256 support and only 1 PCR. The output would be:
$ tpm2_pcrread sha1:0+sha256:0
sha1 :
0 : 0000000000000000000000000000000000000003
sha256 :
0 : 0000000000000000000000000000000000000000000000000000000000000003
OPTIONS
o -o, --output=FILE:
The output file to write the PCR values in binary format, optional.
o -F, --pcrs_format=FORMAT:
Format selection for the binary blob in the PCR output file. `val-
ues' will output a binary blob of the PCR values. `serialized' will
output a binary blob of the PCR values in the form of serialized data
structure in little endian format. Optional. Default is `values'.
COMMON OPTIONS
This collection of options are common to many programs and provide in-
formation that many users may expect.
o -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 re-
quested, the tool will provide errors from man on stderr. If the
"no-man" option if specified, or the manpager fails, the short op-
tions 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.
o -v, --version: Display version information for this tool, supported
tctis and exit.
o -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.
o -Q, --quiet: Silence normal tool output to stdout.
o -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 vari-
able.
The current known TCTIs are:
o tabrmd - The resource manager, called tabrmd
(https://github.com/tpm2-software/tpm2-abrmd). Note that tabrmd and
abrmd as a tcti name are synonymous.
o mssim - Typically used for communicating to the TPM software simula-
tor.
o device - Used when talking directly to a TPM device file.
o 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-op-
tion-config> results in the default being used for that portion respec-
tively.
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 indi-
cate 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 li-
brary name as understood by dlopen(3) semantics.
TCTI OPTIONS
This collection of options are used to configure the various known TCTI
modules available:
o 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="de-
vice:/dev/tpm0"
o 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_TC-
TI="mssim:host=localhost,port=2321"
o abrmd: For the abrmd TCTI, the configuration string format is a se-
ries of simple key value pairs separated by a `,' character. Each
key and value string are separated by a `=' character.
o 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.ex-
ample.FooBar:
\--tcti=tabrmd:bus_name=com.example.FooBar
Specify the default (abrmd) tcti and a config string of bus_type=ses-
sion:
\--tcti:bus_type=session
NOTE: abrmd and tabrmd are synonymous.
PCR bank specifiers (common/pcr.md)
Supported Hash Algorithms
Supported hash algorithms are:
o 0x4 or sha1 for TPM_ALG_SHA1
o 0xB or sha256 for TPM_ALG_SHA256 (default)
o 0xC or sha384 for TPM_ALG_SHA384
o 0xD or sha512 for TPM_ALG_SHA512
o 0x12 or sm3_256 for TPM_ALG_SM3_256
NOTE: Your TPM may not support all algorithms.
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
o rsa
o ecc
Symmetric
o aes
o camellia
Hashing Algorithms
o sha1
o sha256
o sha384
o sha512
o sm3_256
o sha3_256
o sha3_384
o sha3_512
Keyed Hash
o hmac
o xor
Signing Schemes
o rsassa
o rsapss
o ecdsa
o ecdaa
o ecschnorr
Asymmetric Encryption Schemes
o oaep
o rsaes
o ecdh
Modes
o ctr
o ofb
o cbc
o cfb
o ecb
Misc
o null
Complex Specifiers
Objects, when specified for creation by the TPM, have numerous algo-
rithms 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 re-
maining scheme and symmetric details will default based on the type
specified and the type of the object being created.
o aes - Default AES: aes128
o aes128<mode> - 128 bit AES with optional mode (ctr|ofb|cbc|cfb|ecb).
If mode is not specified, defaults to null.
o aes192<mode> - Same as aes128<mode>, except for a 192 bit key size.
o aes256<mode> - Same as aes128<mode>, except for a 256 bit key size.
o ecc - Elliptical Curve, defaults to ecc256.
o ecc192 - 192 bit ECC
o ecc224 - 224 bit ECC
o ecc256 - 256 bit ECC
o ecc384 - 384 bit ECC
o ecc521 - 521 bit ECC
o rsa - Default RSA: rsa2048
o rsa1024 - RSA with 1024 bit keysize.
o rsa2048 - RSA with 2048 bit keysize.
o 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 sign-
ing 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 algo-
rithm, For example: oaep-sha256.
o oaep
o ecdh
o rsassa
o rsapss
o ecdsa
o ecschnorr
Multiple Option Scheme Specifiers
This scheme specifier is followed by a count (max size UINT16) then
followed 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 asym-
metric 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
EXAMPLES
Display all PCR values
tpm2_pcrread
Display the PCR values with a specified bank
tpm2_pcrread sha1
Display the PCR values with specified banks and store in a file
tpm2_pcrread -o pcrs sha1:16,17,18+sha256:16,17,18
Display the supported PCR bank algorithms and exit
tpm2_pcrread
NOTES
The maximum number of PCR that can be dumped at once is associated with
the maximum length of a bank.
On most TPMs, it means that this tool can dump up to 24 PCRs at once.
Returns
Tools can return any of the following codes:
o 0 - Success.
o 1 - General non-specific error.
o 2 - Options handling error.
o 3 - Authentication error.
o 4 - TCTI related error.
o 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)
tpm2-tools tpm2_pcrread(1)