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|
# frozen_string_literal: true
require "cose/algorithm"
require "cose/error"
require "cose/rsapkcs1_algorithm"
require "openssl"
require "webauthn/authenticator_data/attested_credential_data"
require "webauthn/error"
module WebAuthn
module AttestationStatement
class UnsupportedAlgorithm < Error; end
ATTESTATION_TYPE_NONE = "None"
ATTESTATION_TYPE_BASIC = "Basic"
ATTESTATION_TYPE_SELF = "Self"
ATTESTATION_TYPE_ATTCA = "AttCA"
ATTESTATION_TYPE_BASIC_OR_ATTCA = "Basic_or_AttCA"
ATTESTATION_TYPE_ANONCA = "AnonCA"
ATTESTATION_TYPES_WITH_ROOT = [
ATTESTATION_TYPE_BASIC,
ATTESTATION_TYPE_BASIC_OR_ATTCA,
ATTESTATION_TYPE_ATTCA,
ATTESTATION_TYPE_ANONCA
].freeze
class Base
AAGUID_EXTENSION_OID = "1.3.6.1.4.1.45724.1.1.4"
def initialize(statement)
@statement = statement
end
def valid?(_authenticator_data, _client_data_hash)
raise NotImplementedError
end
def format
WebAuthn::AttestationStatement::FORMAT_TO_CLASS.key(self.class)
end
def attestation_certificate
certificates&.first
end
def attestation_certificate_key_id
attestation_certificate.subject_key_identifier&.unpack("H*")&.[](0)
end
private
attr_reader :statement
def matching_aaguid?(attested_credential_data_aaguid)
extension = attestation_certificate&.find_extension(AAGUID_EXTENSION_OID)
if extension
aaguid_value = OpenSSL::ASN1.decode(extension.value_der).value
aaguid_value == attested_credential_data_aaguid
else
true
end
end
def matching_public_key?(authenticator_data)
attestation_certificate.public_key.to_der == authenticator_data.credential.public_key_object.to_der
end
def certificates
@certificates ||=
raw_certificates&.map do |raw_certificate|
OpenSSL::X509::Certificate.new(raw_certificate)
end
end
def algorithm
statement["alg"]
end
def raw_certificates
statement["x5c"]
end
def signature
statement["sig"]
end
def attestation_trust_path
if certificates&.any?
certificates
end
end
def trustworthy?(aaguid: nil, attestation_certificate_key_id: nil)
if ATTESTATION_TYPES_WITH_ROOT.include?(attestation_type)
configuration.acceptable_attestation_types.include?(attestation_type) &&
valid_certificate_chain?(aaguid: aaguid, attestation_certificate_key_id: attestation_certificate_key_id)
else
configuration.acceptable_attestation_types.include?(attestation_type)
end
end
def valid_certificate_chain?(aaguid: nil, attestation_certificate_key_id: nil)
attestation_root_certificates_store(
aaguid: aaguid,
attestation_certificate_key_id: attestation_certificate_key_id
).verify(attestation_certificate, attestation_trust_path)
end
def attestation_root_certificates_store(aaguid: nil, attestation_certificate_key_id: nil)
OpenSSL::X509::Store.new.tap do |store|
root_certificates(
aaguid: aaguid,
attestation_certificate_key_id: attestation_certificate_key_id
).each do |cert|
store.add_cert(cert)
end
end
end
def root_certificates(aaguid: nil, attestation_certificate_key_id: nil)
root_certificates =
configuration.attestation_root_certificates_finders.reduce([]) do |certs, finder|
if certs.empty?
finder.find(
attestation_format: format,
aaguid: aaguid,
attestation_certificate_key_id: attestation_certificate_key_id
) || []
else
certs
end
end
if root_certificates.empty? && respond_to?(:default_root_certificates, true)
default_root_certificates
else
root_certificates
end
end
def valid_signature?(authenticator_data, client_data_hash, public_key = attestation_certificate.public_key)
raise("Incompatible algorithm and key") unless cose_algorithm.compatible_key?(public_key)
cose_algorithm.verify(
public_key,
signature,
verification_data(authenticator_data, client_data_hash)
)
rescue COSE::Error
false
end
def verification_data(authenticator_data, client_data_hash)
authenticator_data.data + client_data_hash
end
def cose_algorithm
@cose_algorithm ||=
COSE::Algorithm.find(algorithm).tap do |alg|
alg && configuration.algorithms.include?(alg.name) ||
raise(UnsupportedAlgorithm, "Unsupported algorithm #{algorithm}")
end
end
def configuration
WebAuthn.configuration
end
end
end
end
|
