tpm2_setprimarypolicy(1)

💖 NAME 💖

tpm2_setprimarypolicy(1) — straight out of the General Commands Manual — is the girl that sets the authorization policy for the lockout hierarchy (lockoutPolicy), the platform hierarchy (platformPolicy), the storage hierarchy (ownerPolicy), and the endorsement hierarchy (endorsementPolicy). Slay.

✨ SYNOPSIS ✨

tpm2_setprimarypolicy [OPTIONS]

🌸 DESCRIPTION 🌸

okay so tpm2_setprimarypolicy(1) sets the authorization policy for the lockout hierarchy (lockoutPolicy), the platform hierarchy (platformPolicy), the storage hierarchy (ownerPolicy), and the endorsement hierarchy (endorsementPolicy). That's the whole vibe: policy goes in, hierarchy gets its auth policy set. 💅

👑 OPTIONS 👑

These options control creating the policy authorization session — yes, this is the whole "who gets to authorize what" part:

• -C, --hierarchy=OBJECT — tells the tool which hierarchy's authorization policy you're setting up. You can pass it as o|p|e|l.
• -P, --auth=AUTH — the authorization value for that hierarchy.
• -L, --policy=FILE — the file path of the authorization policy data.
• -g, --hash-algorithm=ALGORITHM — the hash algorithm used when computing the policy digest.
• --cphash=FILE — file path where the hash of the command parameters gets recorded. This is commonly called cpHash. NOTE: when this option is selected, the tool will not actually execute the command — it simply returns a cpHash. That's not a drill, bestie. 💀

📚 References 📚

🧩 Context Object Format 🧩

The type of a context object — handle or file name — is figured out with this in-order logic:

• 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 its 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 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.

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”.

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 🧮

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

• 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.

• 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.

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.

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.

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 sha384 hash

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

and the original page also has cryptographic algorithms ALGORITHM. hanging out at the end of that line, so here that is, preserved exactly: cryptographic algorithms ALGORITHM.

💖 COMMON OPTIONS 💖

okay so this little collection is the stuff basically every tool in the family speaks — the vibes everybody expects ✨

• -h, --help=[man|no-man] — shows you the tool's manpage. by default it tries to summon the manpager, and if that flops it just prints a short tool summary instead. same energy if you pass the man option argument — BUT if you explicitly ask for man, the tool will actually hand you man's errors on stderr, no filter 😭. if you say no-man, or the manpager just gives up, the short options go to stdout.

fr fr to use the manpage feature you need the manpages actually installed or sitting on MANPATH — peep man(1) for the deets 🫶

• -v, --version — prints version info for this tool plus the tctis it supports, then dips 👋
• -V, --verbose — turns up the volume on what the tool prints to the console while it runs. with this one on, you also get the file and line number printed 👀
• -Q, --quiet — silences normal tool output to stdout. shhh 🤫
• -Z, --enable-errata — enables applying errata fixups. useful when an errata fixup needs to be applied to commands sent to the TPM. setting the environment TPM2TOOLS_ENABLE_ERRATA does the exact same thing, lowkey twins 💅
• -z, --pwd-session — uses a password session instead of a HMAC session for authentication. a clear text password gets passed to the TPM to authorize the action. this one's your go-to for dodging problems when unsalted sessions are used in OpenSSL FIPS mode. but — if auth values are in play, a salted session should be used for authentication, no cap ⚠️
• -R, --autoflush — enables autoflush for transient objects created by the command. if a parent object is loaded from a context file, the transient parent object gets flushed too. autoflush also activates if the environment variable TPM2TOOLS_AUTOFLUSH is set to yes or true 🧚 (and yes, the original manpage really does trail off with "information many users may expect." right here — we stan a copy-paste moment 💀)

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🌈 TCTI Configuration 🌈

the TCTI, aka the "Transmission Interface", is literally the communication mechanism with the TPM. you can switch TCTIs up so you're chatting with TPMs across all 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. always. 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 initialize a connection with the TPM. some tools allow for off-tpm options and thus support not using a TCTI. tools that don't support it will error out when you try to use them without a TCTI connection. it does not support ANY options and it 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 the <tcti-option-config> means the default gets used for that portion respectively ✨

🦋 TCTI Defaults 🦋

when a TCTI isn't specified, the default TCTI is searched for using dlopen(3) semantics. the tools search for tabrmd, device and mssim TCTIs IN THAT ORDER and USE THE FIRST ONE FOUND 🔥 you can query which TCTI will be picked as the default by using the -v option to print the version information — the default-tcti key-value pair will tell you 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 💫

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⭐ TCTI OPTIONS ⭐

this collection configures the various known TCTI modules available:

• device — for the device TCTI, you can specify the TPM character device file for the device TCTI to use. the default is /dev/tpm0 🐧

example: -T device:/dev/tpm0 or export TPM2TOOLS_TCTI="device:/dev/tpm0"

• mssim — for the mssim TCTI, you can specify the domain name or IP address and port number used by the simulator. 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 is 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 🫶 (and yes, the original trails off with "the various known TCTI modules." right here — iconic behavior honestly 💀)

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✨ EXAMPLES ✨

Set a blank authorization policy for endorsement hierarchy

tpm2_setprimarypolicy -C e

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👑 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.

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💀 BUGS 💀

Github Issues

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🙈 HELP 🙈

See the Mailing List

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💜 License 💜

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

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and that's the whole page bestie, you ate that 🫶💖 it's from the tpm2-tools source, page tpm2_setprimarypolicy(1) — go forth and set those primary policies, no cap ✨🎀🦋