tpm2_makecredential(1)

📦

version 5.8 · 10 versions

🦋 tpm2_makecredential(1) 🦋

okay bestie, welcome to the tpm2_makecredential glow-up 💅 this is a General Commands Manual page, and honestly? the manual name is literally tpm2_makecredential — that's it, that's the name, we move. ✨

✨ NAME ✨

tpm2_makecredential(1) — the tool that generates the encrypted-user-chosen-data and the wrapped-secret-data-encryption-key for the privacy-sensitive credentialing process of a TPM object. periodt. 🎀

🌸 SYNOPSIS 🌸

tpm2_makecredential [OPTIONS]

💖 DESCRIPTION 💖

So tpm2_makecredential(1) — here's the vibe. The TPM supports a privacy-preserving protocol for distributing credentials for keys on a TPM. This process guarantees that the credentialed-TPM-object(AIK) is loaded on the same TPM as a well-known public-key-object(EK), and it does that without knowing the specific public properties of the credentialed-TPM-object(AIK). The way privacy is guaranteed? Only the name of the credentialed-TPM-object(AIK) gets shared — never the credentialed-TPM-object's public key itself. iconic behavior, no cap. 👑

Make-credential is literally the first step in this whole process — after receiving the public-key-object(EK) public key of the TPM and the name of the credentialed-TPM-object(AIK), an encrypted-user-chosen-data is generated, and the secret-data-encryption-key is generated and wrapped using cryptographic processes specific to credential activation. That's what guarantees the credentialed-TPM-object(AIK) is loaded on the TPM with the well-known public-key-object(EK). 🫶

And the bestie-est part? tpm2_makecredential can generate the encrypted-user-chosen-data and the wrapped secret-data-encryption-key without a TPM by using the none TCTI option. no hardware? no problem. 😭🔥

⭐ OPTIONS ⭐

-e, --encryption-key=FILE — bestie this one is DEPRECATED, use -u or –public instead. fr fr, let it go. 🙈
-u, --public=FILE — a TPM public key which was used to wrap the seed. 📝 NOTE: this option is the same as -e and it's added to make it similar to other tools that specify the public key. The old option is retained for backwards compatibility.
-G, --key-algorithm=ALGORITHM — the key algorithm associated with the TPM public key. Specify either RSA/ECC. When this option is used, the input public key is expected to be in PEM format and the default TCG EK template is used for the key properties. 🧚
-s, --secret=FILE or STDIN — the secret which will be protected by the key derived from the random seed. Can be specified as a file, or passed from stdin. 🍓
-n, --name=FILE_OR_HEX — the name of the key for which the certificate is to be created. Can either be a path or a hex string.
-o, --credential-blob=FILE — the output file path, recording the encrypted-user-chosen-data and the wrapped secret-data-encryption-key. 💾

🌈 COMMON OPTIONS 🌈

This collection of options is common to many programs and provides information that many users may expect. the classics, basically. 💜

-h, --help=[man|no-man] — display the tool's manpage. By default it attempts to invoke the manpager for the tool, however on failure it will output a short tool summary. This is the same behavior if the man option argument is specified — but 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, the manpages need 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 set to yes or true. 🚿

🌸 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. it's giving ✨ networking era ✨

To control the TCTI, the tools respect:

The command line option -T or --tcti
The environment variable: TPM2TOOLS_TCTI.

NOTE: the command line option always overrides the environment variable. always always. 💅

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. first come, first served bestie 💫

🦋 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 main character moment 👑

💜 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. same thing, different font 💅

🔥 EXAMPLES 🔥

okay here's the whole little ritual, copy it exactly bestie:

       tpm2 createek -Q -c 0x81010009 -G rsa -u ek.pub

       tpm2 createak -C 0x81010009 -c ak.ctx -G rsa -g sha256 -s rsassa -u ak.pub \
       -n ak.name -p akpass> ak.out

       file_size=`ls -l ak.name | awk {'print $5'}`
       loaded_key_name=`cat ak.name | xxd -p -c $file_size`

       tpm2 readpublic -c 0x81010009 -o ek.pem -f pem -Q

       echo "12345678" | tpm2 makecredential -Q -u ek.pem -s - -n $loaded_key_name \
       -o mkcred.out -G rsa

🎀 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 — that's where the drama lives, take it there. 🙈

🫶 HELP 🫶

See the Mailing List 💌

⚖️ License ⚖️

This work is licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0). slay and share alike ✨

and that's the whole page bestie! 💅 this little masterpiece comes to you from tpm2-tools — go forth and make credentials, no cap. 🌈⭐💜

📦 where this page comes from

arch rolling: tpm2-tools 5.8-1 · BSD-3-Clause
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash-1017 on 2026-11-06: a language model's rewrite of the original, under its terms