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pkcs11 tool Configuration

Below, will be examples and discussion on how to use tpm2-pkcs11 with pkcs11-tool.

pkcs11-tool is part of OpenSC and can be installed on ubuntu by issuing the command:

sudo apt-get install opensc

Step 1 - Initializing a Store

Start by reading the document on initialization here. Only brief commands will be provided here, so a a basic understanding of the initialization process is paramount.

We start by creating a tpm2-pkcs11 store and set up an empty token.

tpm2_ptool.py init --path=~/tmp

tpm2_ptool.py addtoken --pid=1 --sopin=mysopin --userpin=myuserpin --label=label --path ~/tmp

Step 2 - Exporting the Store

Since we didn't use the default store location by setting --path in the tpm2-ptool tool, we must export the store so the library can find it. We do this via:

export TPM2_PKCS11_STORE=$HOME/tmp

Note: The tpm2-pkcs11.so library WILL NOT EXPAND ~ and thus you have to use something the shell will expand, like $HOME.

Examples of pkcs11-tool

This will not be exhaustive, as we don't wish to duplicate opensc's documentation of their tool. But we will show case a few commands for users wishing to use this tool with tpm2-pkcs11 project.

For each example below, --module is the path to the pkcs11.so library and will be machine dependent. Note that default builds will provide the library under src/.libs

It makes life simpler to set p an alias, so lets do that, making sure to update--module:

alias tpm2pkcs11-tool='pkcs11-tool --module /path/to/libtpm2_pkcs11.so

Changing USER pin

How to change the user pin from myuserpin to mynewpin

tpm2pkcs11-tool --label="label" --login --pin myuserpin --change-pin --new-pin mynewpin
Using slot 0 with a present token (0x1)
PIN successfully changed

You can see Checking USER pin for example of checking the pin.

Checking USER pin

How to check that the pin is valid. The pin value shown is based off of section Changing USER pin

tpm2pkcs11-tool --label="label" --test --pin mynewpin

Initializing USER pin

How to reset or initialize the user pin given the so pin.

tpm2pkcs11-tool --label="label" --init-pin --so-pin mysopin --pin mynewpin

Generating Random Data

The below example will generate 4 bytes of random data and assumes the pin has been changed as in section Checking USER pin for example of checking the pin.

tpm2pkcs11-tool --label="label" --pin mynewpin --generate-random 4 | xxd
Using slot 0 with a present token (0x1)
00000000: 2e50 bc47                                .P.G

Listing Objects

To list objects, we simply use the --list-objects option:

tpm2pkcs11-tool --list-objects
Private Key Object; EC
  label:      p11-templ-key-label-ecc
  ID:         7031312d74656d706c2d6b65792d69642d65636300
  Usage:      sign
Public Key Object; EC  EC_POINT 256 bits
  EC_POINT:   04410452526c163439c3c5e5a943466a606439fbc7284eafd12221c4473ecb2fba3c586816d54f9ff108489877c5cfa857ba05cfba33dfe3e9b739107f672f787838d6
  EC_PARAMS:  06082a8648ce3d030107
  label:      p11-templ-key-label-ecc
  ID:         7031312d74656d706c2d6b65792d69642d65636300
  Usage:      verify

Note: Your output will likely differ, but the tool should output a list of objects and some attributes.

Creating Objects

Outside of using tpm2_ptool.py to add objects, p11tool supports creating objects through the PKCS#11 interface.

Generating RSA Keypair

This will generate an RSA keypair using pkcs11-tool:

tpm2pkcs11-tool --label="label" --login --pin=myuserpin --keypairgen
Using slot 0 with a present token (0x1)
Key pair generated:
Private Key Object; RSA
  label:      label
  ID:         3332
  Usage:      none
Public Key Object; RSA 2048 bits
  label:      label
  ID:         3333
  Usage:      none

Generating ECC Keypair

This will generate an EC keypair using pkcs11-tool:

tpm2pkcs11-tool --label="my-ecc-keypair" --login --pin=myuserpin --keypairgen --usage-sign --key-type EC:prime256v1
Using slot 0 with a present token (0x1)
Key pair generated:
Private Key Object; EC
  label:      my-ecc-keypair
  ID:         3436
  Usage:      sign
Public Key Object; EC  EC_POINT 256 bits
  EC_POINT:   04410436e7d2c84725234ec8d4b14bc31a50d382eb578cbc7315ae95561875314eb5a22a390bbfabef6269a35a18b1d95b2abc553071c419c3e866db0c3f13c0288ac6
  EC_PARAMS:  06082a8648ce3d030107
  label:      my-ecc-keypair
  ID:         3437
  Usage:      verify

Destroying Objects

Let's destroy the key we created in the Generating ECC Keypair segment, IDs 3436 and 3437 for both the private and public portions respectively.

Private Key

tpm2pkcs11-tool --login --pin=myuserpin --delete-object --type=privkey --id 3436
Using slot 0 with a present token (0x1)

Public Key

tpm2pkcs11-tool --login --pin=myuserpin --delete-object --type=pubkey --id 3437
Using slot 0 with a present token (0x1)

Note: The tool doesn't have any output about successful delete, only when it fails. However, you can run the command in Listing Objects to verify that it is indeed deleted.