tpm2_print(1)

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version 5.8 · 10 versions
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💅 tpm2_print(1) — General Commands Manual ✨

okay bestie, buckle up — this is the manual page for tpm2_print(1), aka the tool that literally prints TPM data structures. yes, the whole thing. no cap, we're going through all of it. 🫶

🌸 NAME 🌸

tpm2_print(1) — Prints TPM data structures. that's the whole name. iconic, honestly. 👑

✨ SYNOPSIS ✨

tpm2_print [OPTIONS] [ARGUMENT or STDIN]

like, options first, then either an argument or stdin. simple. periodt. 💅

🦋 DESCRIPTION 🦋

tpm2_print(1) decodes a TPM data structure and prints the elements inside it to stdout as YAML. yes, YAML. she understood the assignment. 🎀

so you can hand it a file path that contains a TPM object, or a TSS2 Private Key in the PEM format, and that's your path argument. if you don't specify one? it just reads from stdin. lowkey convenient. 🌈

🌟 OPTIONS 🌟

  • -t, --type — Required. it's the type of data structure. the option supports these arguments:
    • TPMS_ATTEST
    • TPMS_CONTEXT
    • TPM2B_PUBLIC
    • TPMT_PUBLIC
    • TSSPRIVKEY_OBJ
    • ESYS_TR
  • ARGUMENT — the command line argument that specifies the path of the TPM data. 🗂️
  • -f, --format — format selection for the public key output file. here's the breakdown, bestie:
    • tss (the default) will output a binary blob according to the TPM 2.0 Specification.
    • pem will output an OpenSSL compatible PEM encoded public key.
    • der will output an OpenSSL compatible DER encoded public key.
    • tpmt will output a binary blob of the TPMT_PUBLIC struct referenced by TPM 2.0 specs.

it's the public key format, okay? and heads up: this only works if option --type/-t is set to TPM2B_PUBLIC or TPMT_PUBLIC. iykyk. 🔥

📚 References 📚

🧚 Context Object Format 🧚

so the type of a context object — whether it's a handle or a 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_.

(yes, the original says "argument argument" and "will be treat" — i'm not fixing it, i'm just reporting the vibes. 💀)

🔐 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”.

for authentication with auth values, the tool commands implicitly generate an HMAC session. thus passwords are not transmitted unencrypted. 🛡️ this does not apply to passwords defined for objects. in this case, an HMAC session should be used (see tpm2_startauthsession(1)).

🍓 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. literally so useful. 😭

✨ Example ✨

hex:1122334455667788

🎀 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. 🫶 protect urself.

✨ 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”. (double "in" — again, not my typo, just the lore. 🙈)

the raw-pcr-file is an optional argument that contains the output of the raw PCR contents as returned by tpm2_pcrread(1).

PCR bank specifiers

✨ 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.

👑 COMMON OPTIONS 👑

this collection of options are common to many programs and provide information that many users may expect. the classics. 💫

  • -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. shhh. 🤫
  • -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.
  • -z, --pwd-session — use password session instead of a HMAC session for authentication. a clear text password is passed to the TPM to authorize the action. this option can be used to avoid problems when unsalted sessions are used in OpenSSL FIPS mode. if auth values are used a salted session should be used for authentication.
  • -R, --autoflush — enable autoflush for transient objects created by the command. if a parent object is loaded from a context file also the transient parent object will be flushed. autoflush can also be activated if the environment variable TPM2TOOLS_AUTOFLUSH is is set to yes or true. information many users may expect. (that trailing sentence is just... there. i don't make the rules. 💀)

🌈 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. 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”. like, exactly. don't get cute. ⚠️

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.
    • the 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.

📚 References 📚

💅 COMMON OPTIONS 💅

okay so this little collection is common to many programs and gives you info that many users expect, bestie. let's go:

  • -h, --help=[man|no-man] — displays the tool's manpage. by default it tries to invoke the manpager for the tool, but if that fails it outputs a short tool summary. same behavior if you pass the man option argument, except if you explicitly request man, the tool will give you errors from man on stderr. if you say no-man, or if the manpager fails, the short options get output to stdout. to successfully use the manpages feature, the manpages need to be installed or on MANPATH; see man(1) for more details.
  • -v, --version — displays version info for this tool, supported tctis, and then exits.
  • -V, --verbose — increases the info the tool prints to the console during execution. when using this option, the file and line number are printed.
  • -Q, --quiet — silences normal tool output to stdout.
  • -Z, --enable-errata — enables 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.
  • -z, --pwd-session — uses a password session instead of a HMAC session for authentication. a clear text password is passed to the TPM to authorize the action. this option can be used to avoid problems when unsalted sessions are used in OpenSSL FIPS mode. if auth values are used, a salted session should be used for authentication.
  • -R, --autoflush — enables autoflush for transient objects created by the command. if a parent object is loaded from a context file, also the transient parent object will be flushed. autoflush can also be activated if the environment variable TPM2TOOLS_AUTOFLUSH is set to yes or true. (and yes, the original also has a stray “information many users may expect.” hanging out at the end of this bullet — keeping it because details are sacred 💅)

🌈 TCTI Configuration 🌈

the TCTI, aka “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. 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 initialize 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. so 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 is 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 defaults 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 a key to generate a quote from 🌸

tpm2_createprimary -C e -c primary.ctx
tpm2_create -C primary.ctx -u key.pub -r key.priv
tpm2_load -C primary.ctx -u key.pub -r key.priv -c key.ctx
tpm2_quote -c key.ctx -l 0x0004:16,17,18+0x000b:16,17,18 -g sha256 -m msg.dat
tpm2_print -t TPMS_ATTEST msg.dat
tpm2_print -t TPM2B_PUBLIC key.pub
tpm2_readpublic -c key.ctx -f tpmt -o key.tpmt
tpm2_print -t TPMT_PUBLIC key.tpmt
tpm2 print -t TPM2B_PUBLIC -f pem key.pub
tpm2 print -t TSSPRIVKEY_OBJ tssprivkey.pem
tpm2 print -t TSSPRIVKEY_OBJ tssprivkey.pem -f pem > publickey.pem

serialized ESYS_TR handles are returned from tools like tpm2_evictcontrol’s -o and tpm2_readpublic’s -t options.

tpm2_createprimary -c primary.ctx
tpm2_evictcontrol -c primary.ctx -o primary.tr
tpm2 print -t ESYS_TR primary.tr

🌈 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

🫶 HELP 🫶

See the Mailing List

📜 License 📜

this work is licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0).

source/version: tpm2-tools · page: tpm2_print(1) · date: the footer doesn't print one, so I'm not inventing it — mwah 💋

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