discourse/lib/discourse_webauthn/base_validation_service.rb
Penar Musaraj 0af6c5efdc
DEV: Refactor webauthn to support passkeys (1/3) ()
This is part 1 of 3, split up of PR . This PR refactors the
webauthn code to support passkey authentication/registration.

Passkeys aren't used yet, that is coming in PRs 2 and 3.

Co-authored-by: Alan Guo Xiang Tan <gxtan1990@gmail.com>
2023-10-03 14:59:28 -04:00

90 lines
2.7 KiB
Ruby

# frozen_string_literal: true
module DiscourseWebauthn
class BaseValidationService
def initialize(current_user, params, session:, factor_type:)
@current_user = current_user
@params = params
@factor_type = factor_type
@session = session
end
def validate_webauthn_type(type_to_check)
return if client_data["type"] == type_to_check
raise(InvalidTypeError, I18n.t("webauthn.validation.invalid_type_error"))
end
def validate_challenge
return if challenge_match?
raise(ChallengeMismatchError, I18n.t("webauthn.validation.challenge_mismatch_error"))
end
def validate_origin
return if origin_match?
raise(InvalidOriginError, I18n.t("webauthn.validation.invalid_origin_error"))
end
def validate_rp_id_hash
return if rp_id_hash_match?
raise(
InvalidRelyingPartyIdError,
I18n.t("webauthn.validation.invalid_relying_party_id_error"),
)
end
## flags per specification
# https://www.w3.org/TR/webauthn-2/#sctn-authenticator-data
# bit 0 - user presence
# bit 1 - reserved for future use
# bit 2 - user verification
# bit 3-5 - reserved for future use
# bit 6 - attested credential data
# bit 7 - extension data
def validate_user_presence
flags = auth_data[32].unpack("b*")[0].split("")
# bit 0 - user presence
return if flags[0] == "1"
raise(UserPresenceError, I18n.t("webauthn.validation.user_presence_error"))
end
def validate_user_verification
flags = auth_data[32].unpack("b*")[0].split("")
# bit 2 - user verification
return if flags[2] == "1"
raise(UserVerificationError, I18n.t("webauthn.validation.user_verification_error"))
end
private
# https://w3c.github.io/webauthn/#sctn-registering-a-new-credential
# Let JSONtext be the result of running UTF-8 decode on the value of response.clientDataJSON.
def client_data_json
@client_data_json ||= Base64.decode64(@params[:clientData])
end
# Let C, the client data claimed as collected during the credential creation, be the result of running
# an implementation-specific JSON parser on JSONtext.
def client_data
@client_data ||= JSON.parse(client_data_json)
end
def challenge_match?
Base64.decode64(client_data["challenge"]) ==
DiscourseWebauthn.challenge(@current_user, @session)
end
def origin_match?
client_data["origin"] == DiscourseWebauthn.origin
end
def rp_id_hash_match?
auth_data[0..31] == OpenSSL::Digest::SHA256.digest(DiscourseWebauthn.rp_id)
end
def client_data_hash
@client_data_hash ||= OpenSSL::Digest::SHA256.digest(client_data_json)
end
end
end