discourse/lib/discourse_webauthn.rb

# frozen_string_literal: true
require "webauthn/challenge_generator"
require "webauthn/security_key_base_validation_service"
require "webauthn/security_key_registration_service"
require "webauthn/security_key_authentication_service"

module DiscourseWebauthn
  ACCEPTABLE_REGISTRATION_TYPE = "webauthn.create"
  ACCEPTABLE_AUTHENTICATION_TYPE = "webauthn.get"

  # -7   - ES256
  # -257 - RS256 (Windows Hello supported alg.)
  SUPPORTED_ALGORITHMS = COSE::Algorithm.registered_algorithm_ids.freeze
  VALID_ATTESTATION_FORMATS = %w[none packed fido-u2f].freeze

  class SecurityKeyError < StandardError
  end

  class InvalidOriginError < SecurityKeyError
  end
  class InvalidRelyingPartyIdError < SecurityKeyError
  end
  class UserVerificationError < SecurityKeyError
  end
  class ChallengeMismatchError < SecurityKeyError
  end
  class InvalidTypeError < SecurityKeyError
  end
  class UnsupportedPublicKeyAlgorithmError < SecurityKeyError
  end
  class UnsupportedAttestationFormatError < SecurityKeyError
  end
  class CredentialIdInUseError < SecurityKeyError
  end
  class MalformedAttestationError < SecurityKeyError
  end
  class NotFoundError < SecurityKeyError
  end
  class OwnershipError < SecurityKeyError
  end
  class PublicKeyError < SecurityKeyError
  end
  class UnknownCOSEAlgorithmError < SecurityKeyError
  end

  ##
  # Usage:
  #
  # These methods should be used in controllers where we
  # are challenging the user that has a security key, and
  # they must respond with a valid webauthn response and
  # credentials.
  def self.stage_challenge(user, secure_session)
    ::DiscourseWebauthn::ChallengeGenerator.generate.commit_to_session(secure_session, user)
  end

  def self.allowed_credentials(user, secure_session)
    return {} if !user.security_keys_enabled?
    credential_ids = user.second_factor_security_key_credential_ids
    {
      allowed_credential_ids: credential_ids,
      challenge: secure_session[self.session_challenge_key(user)],
    }
  end

  def self.challenge(user, secure_session)
    secure_session[self.session_challenge_key(user)]
  end

  def self.rp_id
    Discourse.current_hostname
  end

  def self.rp_name
    SiteSetting.title
  end

  def self.session_challenge_key(user)
    "staged-webauthn-challenge-#{user&.id}"
  end
end