Python PKCS#11 - High Level Wrapper API

A high level, "more Pythonic" interface to the PKCS#11 (Cryptoki) standard to support HSM and Smartcard devices in Python.

The interface is designed to follow the logical structure of a HSM, with useful defaults for obscurely documented parameters. Many APIs will optionally accept iterables and act as generators, allowing you to stream large data blocks for symmetric encryption.

python-pkcs11 also includes numerous utility functions to convert between PKCS #11 data structures and common interchange formats including PKCS #1 and X.509.

python-pkcs11 is fully documented and has a full integration test suite for all features, with continuous integration against multiple HSM platforms including:

• Thales nCipher
• Opencryptoki TPM
• OpenSC/Smartcard-HSM/Nitrokey HSM

Source: https://github.com/danni/python-pkcs11

Documentation: http://python-pkcs11.readthedocs.io/en/latest/

Getting Started

Install from Pip:

pip install python-pkcs11

Or build from source:

python setup.py build

Assuming your PKCS#11 library is set as PKCS11_MODULE and contains a token named DEMO:

AES

import pkcs11

# Initialise our PKCS#11 library
lib = pkcs11.lib(os.environ['PKCS11_MODULE'])
token = lib.get_token(token_label='DEMO')

data = b'INPUT DATA'

# Open a session on our token
with token.open(user_pin='1234') as session:
    # Generate an AES key in this session
    key = session.generate_key(pkcs11.KeyType.AES, 256)

    # Get an initialisation vector
    iv = session.generate_random(128)  # AES blocks are fixed at 128 bits
    # Encrypt our data
    crypttext = key.encrypt(data, mechanism_param=iv)

3DES

import pkcs11

# Initialise our PKCS#11 library
lib = pkcs11.lib(os.environ['PKCS11_MODULE'])
token = lib.get_token(token_label='DEMO')

data = b'INPUT DATA'

# Open a session on our token
with token.open(user_pin='1234') as session:
    # Generate a DES key in this session
    key = session.generate_key(pkcs11.KeyType.DES3)

    # Get an initialisation vector
    iv = session.generate_random(64)  # DES blocks are fixed at 64 bits
    # Encrypt our data
    crypttext = key.encrypt(data, mechanism_param=iv)

RSA

import pkcs11

lib = pkcs11.lib(os.environ['PKCS11_MODULE'])
token = lib.get_token(token_label='DEMO')

data = b'INPUT DATA'

# Open a session on our token
with token.open(user_pin='1234') as session:
    # Generate an RSA keypair in this session
    pub, priv = session.generate_keypair(pkcs11.KeyType.RSA, 2048)

    # Encrypt as one block
    crypttext = pub.encrypt(data)

DSA

import pkcs11

lib = pkcs11.lib(os.environ['PKCS11_MODULE'])
token = lib.get_token(token_label='DEMO')

data = b'INPUT DATA'

# Open a session on our token
with token.open(user_pin='1234') as session:
    # Generate an DSA keypair in this session
    pub, priv = session.generate_keypair(pkcs11.KeyType.DSA, 1024)

    # Sign
    signature = priv.sign(data)

ECDSA

import pkcs11

lib = pkcs11.lib(os.environ['PKCS11_MODULE'])
token = lib.get_token(token_label='DEMO')

data = b'INPUT DATA'

# Open a session on our token
with token.open(user_pin='1234') as session:
    # Generate an EC keypair in this session from a named curve
    ecparams = session.create_domain_parameters(
        pkcs11.KeyType.EC, {
            pkcs11.Attribute.EC_PARAMS: pkcs11.util.ec.encode_named_curve_parameters('secp256r1'),
        }, local=True)
    pub, priv = ecparams.generate_keypair()

    # Sign
    signature = priv.sign(data)

Diffie-Hellman

import pkcs11

lib = pkcs11.lib(os.environ['PKCS11_MODULE'])
token = lib.get_token(token_label='DEMO')

with token.open() as session:
    # Given shared Diffie-Hellman parameters
    parameters = session.create_domain_parameters(pkcs11.KeyType.DH, {
        pkcs11.Attribute.PRIME: prime,  # Diffie-Hellman parameters
        pkcs11.Attribute.BASE: base,
    })

    # Generate a DH key pair from the public parameters
    public, private = parameters.generate_keypair()

    # Share the public half of it with our other party.
    _network_.write(public[Attribute.VALUE])
    # And get their shared value
    other_value = _network_.read()

    # Derive a shared session key with perfect forward secrecy
    session_key = private.derive_key(
        pkcs11.KeyType.AES, 128,
        mechanism_param=other_value)

Elliptic-Curve Diffie-Hellman

import pkcs11

lib = pkcs11.lib(os.environ['PKCS11_MODULE'])
token = lib.get_token(token_label='DEMO')

with token.open() as session:
    # Given DER encocded EC parameters, e.g. from
    #    openssl ecparam -outform der -name <named curve>
    parameters = session.create_domain_parameters(pkcs11.KeyType.EC, {
        pkcs11.Attribute.EC_PARAMS: ecparams,
    })

    # Generate a DH key pair from the public parameters
    public, private = parameters.generate_keypair()

    # Share the public half of it with our other party.
    _network_.write(public[pkcs11.Attribute.EC_POINT])
    # And get their shared value
    other_value = _network_.read()

    # Derive a shared session key
    session_key = private.derive_key(
        pkcs11.KeyType.AES, 128,
        mechanism_param=(pkcs11.KDF.NULL, None, other_value))

Tested Compatibility

Functionality			SoftHSMv2	Thales nCipher	Opencryptoki	OpenSC (Nitrokey)
Get Slots/Tokens			Works	Works	Works	Works
Get Mechanisms			Works	Works	Works	Works
Initialize token			Not implemented
Slot events			Not implemented
Alternative authentication path			Not implemented
Always authenticate keys			Not implemented
Create/Copy		Keys	Works	Works	Errors	Create
		Certificates	Caveats [1]	Caveats [1]	Caveats [1]	?
		Domain Params	Caveats [1]	Caveats [1]	?	N/A
Destroy Object			Works	N/A	Works	Works
Generate Random			Works	Works	Works	Works
Seed Random			Works	N/A	N/A	N/A
Digest (Data & Keys)			Works	Caveats [2]	Works	Works
AES	Generate key		Works	Works	Works	N/A
	Encrypt/Decrypt		Works	Works	Works
	Wrap/Unwrap		? [3]	Works	Errors
	Sign/Verify		Works	Works [4]	N/A
DES2/ DES3	Generate key		Works	Works	Works	N/A
	Encrypt/Decrypt		Works	Works	Works
	Wrap/Unwrap		?	?	?
	Sign/Verify		?	?	?
RSA	Generate key pair		Works	Works	Works	Works [4] [8]
	Encrypt/Decrypt		Works	Works	Works	Decrypt only [9]
	Wrap/Unwrap		Works	Works	Works	N/A
	Sign/Verify		Works	Works	Works	Works
DSA	Generate parameters		Works	Error	N/A	N/A
	Generate key pair		Works	Caveats [5]
	Sign/Verify		Works	Works [4]
DH	Generate parameters		Works	N/A	N/A	N/A
	Generate key pair		Works	Caveats [6]
	Derive Key		Works	Caveats [7]
EC	Generate key pair		Caveats [6]	? [3]	N/A	Works
	Sign/Verify (ECDSA)		Works [4]	? [3]		Sign only [9]
	Derive key (ECDH)		Works	? [3]		?
Proprietary extensions			N/A	Not implemented	N/A	N/A

[1]	(1, 2, 3, 4, 5) Device supports limited set of attributes.

[2]	Digesting keys is not supported.

[3]	(1, 2, 3, 4) Untested: requires support in device.

[4]	(1, 2, 3, 4) Default mechanism not supported, must specify a mechanism.

[5]	From existing domain parameters.

[6]	(1, 2) Local domain parameters only.

[7]	Generates security warnings about the derived key.

[8]	store parameter is ignored, all keys are stored.

[9]	(1, 2) Encryption/verify not supported, extract the public key

Python version:

• 3.4 (with aenum)
• 3.5 (with aenum)
• 3.6

PKCS#11 versions:

• 2.11
• 2.20
• 2.40

Feel free to send pull requests for any functionality that's not exposed. The code is designed to be readable and expose the PKCS #11 spec in a straight-forward way.

If you want your device supported, get in touch!

More info on PKCS #11

The latest version of the PKCS #11 spec is available from OASIS:

http://docs.oasis-open.org/pkcs11/pkcs11-base/v2.40/pkcs11-base-v2.40.html

You should also consult the documentation for your PKCS #11 implementation. Many implementations expose additional vendor options configurable in your environment, including alternative features, modes and debugging information.

License

MIT License

Copyright (c) 2017 Danielle Madeley

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.