Request an enterprise attestation certificate from a FIDO2 device that supports EA and dump the attestation statement and all known attestation certificate extensions.

test_enterprise_attestation.py

# Copyright (c) 2021 Yubico AB
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"""
This example shows how to request and decode an Enterprise Attestation (EA) attestation from an authenticator.

It connects to the first FIDO device found (starts from USB, then looks into NFC),
creates a new credential for it while requesting EA, and then unpacks and decodes the attestation certificate. 
It does *not* validate the certificate or certificate chain in any way.
On Windows, the native WebAuthn API will be used.
"""
from fido2.hid import CtapHidDevice
from fido2.client import Fido2Client, WindowsClient, UserInteraction
from fido2.server import Fido2Server
from fido2.attestation import AttestationVerifier
from base64 import b64decode
from getpass import getpass
import sys
import ctypes

from cryptography import x509
from cryptography.hazmat.backends import default_backend
from cryptography.x509 import UnrecognizedExtension

import asn1
from uuid import UUID

if len( sys.argv ) > 1:
    RPID =  sys.argv[1]
else:
    RPID = input("RPID to test:")


YUBICO_FIDO_DEVICE_TYPE = {
    '1.3.6.1.4.1.41482.1.1': 'YubiKey U2F PlayStore devices (NXP-based)', 
    '1.3.6.1.4.1.41482.1.2': 'YubiKey NEO (NXP-based)',
    '1.3.6.1.4.1.41482.1.3': 'YubiKey Plus (Infineon-based)',
    '1.3.6.1.4.1.41482.1.4': 'YubiKey Edge (Infineon-based)',
    '1.3.6.1.4.1.41482.1.5': 'YubiKey 4 USB (Infineon-based) [2015-11-03]',
    '1.3.6.1.4.1.41482.1.6': 'YubiKey NFC Preview (Infineon-based) [2018-04-12]',
    '1.3.6.1.4.1.41482.1.7': 'YubiKey 5 [2018-09-14]',
    '1.3.6.1.4.1.41482.1.8': 'YubiKey 5 Ci Lightning preview [2019-02-08]',
    '1.3.6.1.4.1.41482.1.9': 'YubiKey Bio',
    }

YUBICO_ATTESTATION_OIDS = {
    'Firmware version':                     '1.3.6.1.4.1.41482.13.1',
    'Enterprise Attestation Serial Number': '1.3.6.1.4.1.45724.1.1.2',
    'Yubico FIDO Device Type':              '1.3.6.1.4.1.41482.2',
    'Transports':                           '1.3.6.1.4.1.45724.2.1.1',
    'AAGUID':                               '1.3.6.1.4.1.45724.1.1.4',
    'FIPS Certificate':                     '1.3.6.1.4.1.41482.12',
    }


YUBICO_FIPS_CERTIFICATES = {
    1: 'YubiKey Standard and YubiKey Nano Certificate #2267',
    2: 'YubiKey (4) FIPS Certificate #3204',
    3: 'YubiKey (4) FIPS Certificate #3517',
    4: 'YubiKey 5 FIPS Certificate #3907 (Level 1)',
    5: 'YubiKey 5 FIPS Certificate #3914 (Level 2)',
    6: 'YubiHSM 2 Certificate #3916',
    7: 'YubiKey 5 FIPS Certificate #3914 (Level 2) update',
    }

def decodefirmwareversion(raw):
    decoder = asn1.Decoder()
    decoder.start(raw)
    tag, value = decoder.read()
    major = value[0]
    minor = value[1]
    patch = value[2]
    return major, minor, patch

def decodeserial(raw):
    decoder = asn1.Decoder()
    decoder.start(raw)
    tag, value = decoder.read()
    sn = str(int.from_bytes(value, byteorder='big', signed=False))
    return sn

def decodetransports(raw):
    #b'\x03\x02\x040'
    assert(raw[0] == 3)
    assert(raw[1] == 2)
    
    #by shifting right and then left by raw[2] bytes, ensure that the "unused" bits in the bit string are always 0.  Probably not needed.
    transportflags =  (raw[3] >> raw[2]) << raw[2]
    transports = []

    # Order for possibletransports in important, and must follow this
    # https://fidoalliance.org/specs/fido-u2f-v1.2-ps-20170411/fido-u2f-authenticator-transports-extension-v1.2-ps-20170411.html
    possibletransports = ["Bluetooth Classic","BLE","USB","NFC","USB (Internal)"]

    # test the 1st bit in the bitstring, if it's a 1, label it with the transport name and then shift left
    for possible in possibletransports:
        #print(possible, transportflags)
        if (transportflags & 0x80):
            transports.append(possible)
        transportflags = (transportflags << 1) & 0xff
    return transports

def decodeaaguid(raw):
    decoder = asn1.Decoder()
    decoder.start(raw)
    tag, value = decoder.read()
    aaguid = UUID(int=int.from_bytes(value, 'big'))
    return aaguid


# Handle user interaction
class CliInteraction(UserInteraction):
    def prompt_up(self):
        print("\nTouch your authenticator device now...\n")

    def request_pin(self, permissions, rd_id):
        return getpass("Enter PIN: ")

    def request_uv(self, permissions, rd_id):
        print("User Verification required.")
        return True


if WindowsClient.is_available() and not ctypes.windll.shell32.IsUserAnAdmin():
    # Enterprise Attestation is currently not supported by python-fido2 while using the Windows WebAuthn API 
    # https://github.com/Yubico/python-fido2/blob/edcb00bc327453cfcf549ef4f12cc25a88b6b0a4/fido2/win_api.py#L814
    # client = WindowsClient("https://"+RPID)
    raise Exception("Enterprise Attestation is currently not supported by python-fido2 while using the Windows WebAuthn API, please run as administrator.")
else:
    # Locate a device
    dev = next(CtapHidDevice.list_devices(), None)
    if dev is not None:
        print("Use USB HID channel.")
    else:
        try:
            from fido2.pcsc import CtapPcscDevice

            dev = next(CtapPcscDevice.list_devices(), None)
            print("Use NFC channel.")
        except Exception as e:
            print("NFC channel search error:", e)

    if not dev:
        print("No FIDO device found")
        sys.exit(1)

    # Set up a FIDO 2 client using the origin provided on the command line
    client = Fido2Client(dev, ("https://"+RPID), user_interaction=CliInteraction())

server = Fido2Server(
    {"id": RPID, "name": "Example RP"},
    attestation="enterprise"
)

user = {"id": b"user_id", "name": "A. User"}

# Prepare parameters for makeCredential
create_options, state = server.register_begin(
    user, user_verification="discouraged", authenticator_attachment="cross-platform",
)

# Create a credential
result = client.make_credential(create_options["publicKey"])

# Complete registration
auth_data = server.register_complete(
    state, result.client_data, result.attestation_object
)

print("New credential created.  Attestation received.")

cert = x509.load_der_x509_certificate(result.attestation_object.att_stmt['x5c'][0], default_backend())

# Test for EA, and get SN
try:
    #oid = '1.3.6.1.4.1.45724.1.1.2'
    #description = 'Enterprise Attestation Serial Number:'
    extension = cert.extensions.get_extension_for_oid(x509.ObjectIdentifier(YUBICO_ATTESTATION_OIDS["Enterprise Attestation Serial Number"])).value.value
    sn = decodeserial(extension)
    #print(oid, description, sn)
    attestationtype="Enterprise"
except:
    attestationtype="Direct"

# Yubico Firmware Version
try:
    #oid='1.3.6.1.4.1.41482.13.1'
    extension = cert.extensions.get_extension_for_oid(x509.ObjectIdentifier(YUBICO_ATTESTATION_OIDS["Firmware version"])).value.value
    major, minor, patch = decodefirmwareversion(extension)
except:
    major = False

# Yubico Device Type
try:
    extension = cert.extensions.get_extension_for_oid(x509.ObjectIdentifier(YUBICO_ATTESTATION_OIDS["Yubico FIDO Device Type"])).value.value
    devicetype = YUBICO_FIDO_DEVICE_TYPE[extension.decode()]
except:
    devicetype = False

# Transports
try:
    extension = cert.extensions.get_extension_for_oid(x509.ObjectIdentifier(YUBICO_ATTESTATION_OIDS["Transports"])).value.value
    transports = decodetransports(extension)
except:
    transports = False

# AAGUID
try:
    extension = cert.extensions.get_extension_for_oid(x509.ObjectIdentifier(YUBICO_ATTESTATION_OIDS["AAGUID"])).value.value
    aaguid = decodeaaguid(extension)
except:
    aaguid = False

# FIPS Certificate
try:
    extension = cert.extensions.get_extension_for_oid(x509.ObjectIdentifier(YUBICO_ATTESTATION_OIDS["FIPS Certificate"])).value.value
    aaguid = decodeaaguid(extension)
except:
    aaguid = False


print("Attestation Certificate Subject:", cert.subject.rfc4514_string())
print("Attestation Certificate Issuer :", cert.issuer.rfc4514_string())
print("Attestation Type:              :", attestationtype)
if attestationtype=="Enterprise":
    print("Serial Number                  :", sn)
if major and minor and patch:
    print("Yubico Firmware Version        : ", major, ".", minor, ".", patch, sep = '')        
if devicetype:
    print("Yubico Device Type             :", devicetype)
if transports:
    print("Yubico Device Transports       :", transports)
if aaguid:
    print("AAGUID                         :", aaguid)

for extension in cert.extensions:
    if extension.oid.dotted_string not in YUBICO_ATTESTATION_OIDS.values():
        if type(extension.value) is x509.UnrecognizedExtension:
            print("Unknown Extension:", extension.oid.dotted_string)

print("Attestation Object",result.attestation_object.hex())