tpm2_ecephemeral(1)

📦
version 5.8 · 10 versions
, in arch rolling

okay so this is tpm2_ecephemeral(1) 💅✨

🎀 NAME 🎀

tpm2_ecephemeral(1) — Creates an ephemeral key for use in a two-phase key exchange protocol.

🦋 SYNOPSIS 🦋

tpm2_ecephemeral [OPTIONS]

🌸 DESCRIPTION 🌸

tpm2_ecephemeral(1) — okay so basically this tool creates an ephemeral key for use in a two-phase key exchange protocol. That's the whole vibe. It's giving "temporary but essential" energy, fr fr.

✨ OPTIONS ✨

  • ARGUMENT=ALGORITHM: — Specify the ECC curve. Example ecc521. This is where you pick your curve bestie, like choosing your aesthetic but for cryptography 💖
  • -u, --public=FILE — Specify the file path to save the ephemeral public point Q ≔ [r]G. That's the public part you're gonna share with the other side, no cap.
  • -t, --counter=FILE — Specify file path to save the least-significant 16 bits of commit count. Just the last 16 bits, lowkey iconic.
  • --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. So like, it's doing the math but not the thing, iykyk.

🔍 References — Algorithm Specifiers 😎

Options that take algorithms support "nice-names". That means you don't gotta type raw binary nonsense, you can just say rsa and it gets it.

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. So like, not everything works everywhere, vibe check required.

🌈 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. Slay.

🧚 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 🌸

Objects, when specified for creation by the TPM, have numerous algorithms 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 remaining scheme and symmetric details will default based on the type specified and the type of the object being created. So you gotta at least give the type, bestie.

  • 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, is an optional field, it can be skipped. 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. It's giving "choose your own adventure" but cryptographic.

🦋 Hash Optional Scheme Specifiers 🦋

These scheme specifiers are 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. So like, you can be specific or just let it vibe with the default.

🧚 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. So if you're like "idk just pick something" it's gonna be that.

✨ 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 cryptographic algorithms ALGORITHM.

🫶 COMMON OPTIONS 🫶

This collection of options are common to many programs and provide information that many users may expect. Like the besties of command-line flags, always there for you.

  • -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. So like, make sure you actually have the docs installed, bestie.

  • -v, --version — Display version information for this tool, supported tctis and exit. Quick vibe check on what you're working with.
  • -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. For when you wanna know exactly what's going down.
  • -Q, --quiet — Silence normal tool output to stdout. Shhh, no talking, just doing.
  • -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. It's like a patch but for the command line.
  • -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. It's giving "old school but sometimes necessary" energy.
  • -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. So like, clean up after yourself automatically.

🌈 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 the plug that connects you to the TPM, basically.

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. Command line is main character energy, periodt.

The current known TCTIs are:

  • tabrmd — The resource manager, called tabrmd. Note that tabrmd and abrmd as a tcti name are synonymous. Same vibe, different name.
  • mssim — Typically used for communicating to the TPM software simulator. For when you're just vibing in software.
  • device — Used when talking directly to a TPM device file. Direct connection, no middleman.
  • 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". So like, if you're not using a TPM, you literally type "none" and nothing else.

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. So you can be like "just use defaults" and it will.

💅 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. So like, it's got a priority list and it's gonna pick the first one that's available.

🦋 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. So like, if you made your own TCTI, you can use it, no cap.

💖 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"

So like if your TPM is at a different path, you can tell it.

  • 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"

For when your simulator is living somewhere else.

  • 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. So like, don't get confused, they're the same thing.

🌟 EXAMPLES 🌟

tpm2_ecephemeral -u ecc.q -t ecc.ctr ecc256

That's it. That's the example. Clean, simple, iconic.

🍓 Returns 🍓

Tools can return any of the following codes:

  • 0 — Success. You did it bestie! 🎉
  • 1 — General non-specific error. Something went wrong but it's not telling you what.
  • 2 — Options handling error. You probably typed a flag wrong.
  • 3 — Authentication error. Wrong password or auth, denied.
  • 4 — TCTI related error. The communication with the TPM broke.
  • 5 — Non supported scheme. Applicable to tpm2_testparams. That scheme wasn't it.

💀 BUGS 💀

Github Issues. Like, if you find a bug, that's where it goes.

👑 HELP 👑

See the Mailing List. For when you need help from the community.

🌈 MANPAGE 🌈

okay bestie, that's part 1! part 2 is totally coming, so don't go anywhere 💖✨

📜 License

Okay bestie, legal bit time — but it's actually the nice kind, no cap 💖 This work is licensed under the Creative Commons Attribution 4.0 International License (CC BY 4.0).

That's it. That's the whole section. Slay, honestly.

And that's a wrap on tpm2_ecephemeral(1), bestie!! 🎀✨ This iconic little page comes to you straight from the tpm2-tools collection and lives as tpm2_ecephemeral(1) — go forth and create those ephemeral keys, you absolute cryptography main character 👑🦋 periodt 💅

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