tpm2_create(1)

📦
version 5.8 · 10 versions
, in arch rolling

✨ NAME ✨

Bestie, this is tpm2_create(1) from the General Commands Manual. The official little label is: tpm2_create(1) — Create a child object.

✨ SYNOPSIS ✨

tpm2_create [OPTIONS]

💖 DESCRIPTION 💖

Okay so tpm2_create(1) creates a child object, and that object can be either a key or a sealing object. A sealing object lets you seal user data to the TPM, with a max size of 128 bytes — tiny but mighty, bestie. Also, it will load the created object if -c is specified. Slay.

🎀 OPTIONS 🎀

These options are for creating the TPM entity:

  • -C, --parent-context=OBJECT — the parent of the object to be created.
  • -P, --parent-auth=AUTH — the authorization value of the parent object specified with -C.
  • -p, --key-auth=AUTH — the authorization value for the created object.
  • -g, --hash-algorithm=ALGORITHM — the hash algorithm for generating the object’s name. This is optional and defaults to sha256 when not specified.
  • -G, --key-algorithm=ALGORITHM — the key algorithm associated with this object. It defaults to “rsa” if not specified.
  • -a, --attributes=ATTRIBUTES — the object attributes, optional. The default for created objects is:
TPMA_OBJECT_SIGN_ENCRYPT|TPMA_OBJECT_DECRYPT|TPMA_OBJECT_FIXEDTPM|
TPMA_OBJECT_FIXEDPARENT|TPMA_OBJECT_SENSITIVEDATAORIGIN|
TPMA_OBJECT_USERWITHAUTH

When -i is specified for sealing, TPMA_OBJECT_SIGN_ENCRYPT and TPMA_OBJECT_DECRYPT are removed from the default attribute set. The algorithm is set in a way where the object is only good for sealing and unsealing. I.e. one cannot use an object for sealing and cryptography operations.

When -L is specified for adding policy based authorization information AND no string password is specified, the attribute TPMA_OBJECT_USERWITHAUTH is cleared unless an explicit choice is made by setting of the attribute with -a option. This prevents creation of objects with inadvertent auth model where in user intended to enforce a policy but inadvertently created an object with empty auth which can be used instead of policy authorization. Important little auth-model caution, bestie.

  • -i, --sealing-input=FILE or STDIN — the data file to be sealed, optional. If file is -, read from stdin. When sealing data only the TPM_ALG_KEYEDHASH algorithm with a NULL scheme is allowed. Thus, -G cannot be specified.
  • -L, --policy=FILE or HEX_STRING — the input policy file or a hex string, optional.
  • -u, --public=FILE — the output file which contains the public portion of the created object, optional.
  • -r, --private=FILE — the output file which contains the sensitive portion of the object, optional.

🛡️ Protection Details 🛡️

Objects that can move outside of TPM need to be protected (confidentiality and integrity). For instance, transient objects require that TPM protected data (key or seal material) be stored outside of the TPM. This is seen in tools like tpm2_create(1), where the -r option outputs this protected data. This blob contains the sensitive portions of the object. The sensitive portions of the object are protected by the parent object, using the parent’s symmetric encryption details to encrypt the sensitive data and HMAC it.

In-depth details can be found in sections 23 of:

Notably Figure 20 is relevant, even though it’s specifically referring to duplication blobs, the process is identical.

If the output is from tpm2_duplicate(1), the output will be slightly different, as described fully in section 23.

  • -c, --key-context=FILE — the output file which contains the key context, optional. The key context is analogous to the context file produced by tpm2_load(1), however is generated via a tpm2_createloaded(1) command. This option can be used to avoid the normal tpm2_create(1) and tpm2_load(1) command sequences and do it all in one command, atomically. One-command energy, iconic.
  • --creation-data=FILE — an optional file output that saves the creation data for certification.
  • --template-data=FILE — an optional file output that saves the key template data (TPM2B_PUBLIC) to be used in tpm2_policytemplate.
  • -t, --creation-ticket=FILE — an optional file output that saves the creation ticket for certification.
  • -d, --creation-hash=FILE — an optional file output that saves the creation hash for certification.
  • -q, --outside-info=HEX_STR_OR_FILE — an optional hex string or path to add unique data to the creation data. Note that it does not contribute in creating statistically unique object.
  • -l, --pcr-list=PCR — the list of PCR banks and selected PCRs’ ids for each bank to be included in the creation data for certification.
  • --cphash=FILE — file path to record the hash of the command parameters. This is commonly termed as cpHash. NOTE: When this option is selected, The tool will not actually execute the command, it simply returns a cpHash. No actual command run — just the hash, bestie.
  • --rphash=FILE — file path to record the hash of the response parameters. This is commonly termed as rpHash.
  • -S, --session=FILE — the session created using tpm2_startauthsession. Multiple of these can be specified. For example, you can have one session for auditing and another for encryption/decryption of the parameters.
  • -f, --format — format selection for the public key output file. 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.

Public key format.

  • -o, --output=FILE — the output file path, recording the public portion of the object.

🦋 REFERENCES 🦋

🧚 Context Object Format 🧚

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 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_.

🌸 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.

🌈 Example 🌈

hex:1122334455667788

🧚 File 🧚

A file based password, specified by 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.

🫶 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 the section “PCR bank specifiers”.

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.

🌈 ALGORITHM SPECIFIERS 🌈

Okay bestie, so any option that takes an algorithm? It supports ✨nice-names✨. Yes that's the actual term, we love that for us.

There are two major algorithm specification string classes: simple and complex. And heads up — the TPM only accepts certain algorithms, based on usage and conditions. So like, don't just throw anything at it and expect it to slay 💅

🌸 Simple specifiers

These are literally just strings with no extra specification data attached. When you're creating objects, the non-specified parts of an object are assumed to be defaults, iykyk. The full list of known "Simple Specifiers" is right below 👇

🦋 Asymmetric

  • rsa
  • ecc

🦋 Symmetric

  • aes
  • camellia
  • sm4

🦋 Hashing Algorithms

  • sha1
  • sha256
  • sha384
  • sha512
  • sm3_256
  • sha3_256
  • sha3_384
  • sha3_512

🦋 Keyed Hash

  • hmac
  • xor

🦋 Signing Schemes

  • rsassa
  • rsapss
  • ecdsa
  • ecdaa
  • ecschnorr
  • sm2

🦋 Asymmetric Encryption Schemes

  • oaep
  • rsaes
  • ecdh

🦋 Modes

  • ctr
  • ofb
  • cbc
  • cfb
  • ecb

🦋 Misc

  • null

🎀 Complex Specifiers

Okay so when objects get specified for creation by the TPM, they've got a whole bunch of algorithms to populate in the public data. We're talking type, scheme, asymmetric details, key size, all of it, the whole vibe check.

Here's the general format for specifying all this data:

<type>:<scheme>:<symmetric-details>

👑 Type Specifiers

This part of the complex algorithm specifier is required, no cap. The remaining scheme and symmetric details will default based on the type you specify and the type of object being created 💖

  • aes — Default AES: aes128
  • aes128<mode> — 128 bit AES with optional mode (ctr|ofb|cbc|cfb|ecb). If mode is not specified, defaults to null.
  • aes192<mode> — Same as aes128<mode>, except for a 192 bit key size.
  • aes256<mode> — Same as aes128<mode>, except for a 256 bit key size.
  • sm4 — Default SM4: sm4128
  • sm4128 or sm4_128 <mode> — 128 bit SM4 with optional mode (ctr|ofb|cbc|cfb|ecb). If mode is not specified, defaults to null.
  • ecc — Elliptical Curve, defaults to ecc256.
  • ecc192 or ecc_nist_p192 — 192 bit ECC NIST curve
  • ecc224 or ecc_nist_p224 — 224 bit ECC NIST curve
  • ecc256 or ecc_nist_p256 — 256 bit ECC NIST curve
  • ecc384 or ecc_nist_p384 — 384 bit ECC NIST curve
  • ecc521 or ecc_nist_p521 — 521 bit ECC NIST curve
  • ecc_sm2 or ecc_sm2_p256 — 256 bit SM2 curve
  • rsa — Default RSA: rsa2048
  • rsa1024 — RSA with 1024 bit keysize.
  • rsa2048 — RSA with 2048 bit keysize.
  • rsa3072 — RSA with 3072 bit keysize.
  • rsa4096 — RSA with 4096 bit keysize.

👑 Scheme Specifiers

Next up is an optional field — you can totally skip it, it's giving "no pressure" 🫶

Schemes are usually Signing Schemes or Asymmetric Encryption Schemes. Most signing schemes take a hash algorithm directly following the signing scheme. If the hash algorithm is missing, it defaults to sha256. Some take no arguments, and some take multiple arguments. chaotic but we respect it.

👑 Hash Optional Scheme Specifiers

These scheme specifiers get followed by a dash and a valid hash algorithm. For example: oaep-sha256.

  • oaep
  • ecdh
  • rsassa
  • rsapss
  • ecdsa
  • ecschnorr
  • sm2

👑 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 asymmetric 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 a sha384 hash

/tpm2_create -C parent.ctx -G ecc256:ecdaa4-sha384 -u key.pub -r key.priv cryptographic algorithms ALGORITHM.

💜 Object Attributes

Object Attributes are used to control various properties of created objects. When specified as an option, either the raw bitfield mask or "nice-names" may be used. The values are in Table 31 Part 2 of the TPM2.0 specification, which you can find here:

https://trustedcomputinggroup.org/wp-content/uploads/TPM-Rev-2.0-Part-2-Structures-01.38.pdf

Nice names are calculated by taking the name field of table 31 and removing the prefix TPMA_OBJECT_ and lowercasing the result. So TPMA_OBJECT_FIXEDTPM becomes fixedtpm. Slay, honestly. Nice names can be joined using the bitwise or | symbol 🎀

For instance, to set the fields TPMA_OBJECT_FIXEDTPM, TPMA_OBJECT_NODA, and TPMA_OBJECT_SIGN_ENCRYPT, the argument would be:

fixedtpm|noda|sign

...specifying the object attributes ATTRIBUTES.

✨ COMMON OPTIONS ✨

This collection of options is common to many programs and provides 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 is 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. Detective mode 🔍
  • -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 set to yes or true. information many users may expect.

🦋 TCTI Configuration

The TCTI, aka the "Transmission Interface", is the communication mechanism with the TPM. TCTIs can be changed for communication with TPMs across different mediums. Versatile icon behavior 💅

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. Periodt. 👑

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".

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. Bring your own TCTI, we love a DIY moment 🧚

🔥 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. the various known TCTI modules. 💀

✨ EXAMPLES ✨

🎀 Setup

okay so bestie, before you can create anything, you need a primary key to act as its parent. like you can't just spawn an object out of the void, that's not how the TPM works 💅

tpm2_createprimary -c primary.ctx

🦋 Create an Object

this one's the classic, the moment, the main character move — it creates an object using all the default values and stashes the TPM sealed private portion and public portion at the paths you give with -u and -r respectively. and lowkey the best part? the tool defaults to an RSA key 🔥

tpm2_create -C primary.ctx -u obj.pub -r obj.priv

🌸 Seal Data to the TPM

so it's not just key objects, bestie — the TPM also lets you seal small amounts of user-specified data right to the TPM itself. it's giving secret diary energy 🙈

echo "my sealed data" > seal.dat
tpm2_create -C primary.ctx -i seal.dat -u obj.pub -r obj.priv

🧚 Create an EC Key Object and Load it to the TPM

okay so normally when you create an object you only get the public and private portions back, and the caller has to use tpm2_load(1) to load those portions into the TPM before actually being able to use the object. however 💫 — this command can do that for you too, when supported by the TPM.

you can vibe check whether your TPM supports this feature by making sure the tpm2_getcap(1) command returns TPM2_CC_CreateLoaded in the command set. if your TPM does not support TPM2_CC_CreateLoaded, an unsuported command code error will be returned (yes that's the original spelling, no I will not be fixing it 🫶). if it's not supported you gotta use tpm2_load(1) — see that manpage for the deets on its usage.

tpm2_create -C primary.ctx -G ecc -u obj.pub -r obj.priv -c ecc.ctx

🌈 Create an Object and get the public key as a PEM file

this creates an object using all the default values but also outputs the public key as a PEM file which is compatible with tools like OpenSSL and literally whatever supports PEM files. iconic behavior honestly 👑

tpm2_create -C primary.ctx -u obj.pub -r obj.priv -f pem -o obj.pem

⭐ Create a restricted RSA signing key

for a restricted signing key you must specify the scheme and null for the symmetric algorithm. no shortcuts, that's the rule 🎀

tpm2_create -C primary.ctx -Grsa2048:rsapss:null  \
    -a "fixedtpm|fixedparen|sensitivedataorigin|userwithauth|restricted|sign" \
    -r obj.priv -u obj.pub

💀 Returns

tools can return any of these codes, bestie — memorize the list, it's giving cheat sheet ✨

  • 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 — yes that's the whole thing, go file one if something's cursed 💅

🫶 HELP

See the Mailing List — the community is there, they're sweet, they got you 🌸

👑 License

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

and that's the whole page, bestie!! 🎀 this lil beauty comes to you from the tpm2-tools fam and it's dated March 2026 — go forth and create objects, you absolute queen 💖✨🦋

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