--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/yubikey/init.lua Wed Feb 16 20:29:33 2011 +0000
@@ -0,0 +1,124 @@
+local _M = {};
+
+local aeslua = require "aeslua";
+local ciphermode = require "aeslua.ciphermode";
+local crc16 = require "crc16";
+
+local modhex2hex;
+do
+ local modhex_map = {};
+ local modhex_chars = "cbdefghijklnrtuv";
+ for i=1,16 do
+ modhex_map[modhex_chars:sub(i,i)] = ("%x"):format(i-1);
+ end
+ function modhex2hex(modhex)
+ if modhex then
+ return (modhex:gsub(".", modhex_map));
+ end
+ end
+end
+_M.modhex2hex = modhex2hex;
+
+local function hex2bin(hex)
+ if hex then
+ return (hex:gsub("..", function (c) return string.char(tonumber(c, 16)); end));
+ end
+end
+_M.hex2bin = hex2bin;
+
+local function bin2hex(bin)
+ if bin then
+ return (bin:gsub(".", function (b) return ("%02x"):format(b:byte()); end));
+ end
+end
+_M.bin2hex = bin2hex;
+
+local otp_parser = {};
+local otp_parser_mt = { __index = otp_parser };
+
+function _M.new_fetch_key_hex(fetchkeyhex)
+ return function (...) return hex2bin(fetchkeyhex(...)); end
+end
+
+function _M.new_otp_parser(config)
+ return setmetatable({
+ config = config,
+ }, otp_parser_mt);
+end
+
+function otp_parser:parse(otp, key)
+ -- Password is any extra data before the real OTP
+ local password;
+ if #otp > 32 + self.config.prefix_length then
+ password = otp:sub(1, #otp - (32 + self.config.prefix_length));
+ otp = otp:sub(#password+1);
+ end
+ local prefix = otp:sub(1, self.config.prefix_length);
+ local token = otp:sub(#prefix+1);
+ if not key then
+ key = self.config.fetch_key(prefix);
+ else
+ key = hex2bin(key);
+ end
+ if not key then return false, "no-key"; end
+ key = {key:byte(1,#key)}
+ local decrypted = ciphermode.decryptString(key, hex2bin(modhex2hex(token)), ciphermode.decryptCBC);
+ if not decrypted then return false, "decrypt-failed"; end
+ -- Extract private UID
+ local uid = decrypted:sub(1,6);
+ -- Build insertion counter (2 bytes)
+ local use1, use2 = decrypted:sub(7,8):byte(1,2);
+ local use_ctr = use1 + math.pow(2, 8)*use2;
+ -- Build timestamp (3 bytes)
+ local time1, time2, time3 = decrypted:sub(9,11):byte(1,3);
+ local timestamp = time1 + math.pow(2,8)*time2 + math.pow(2, 16)*time3;
+ -- Extract session counter (1 byte)
+ local session_ctr = decrypted:sub(12, 12):byte();
+
+ if crc16.hash(decrypted) ~= 0xf0b8 then
+ return false, "invalid-checksum";
+ end
+
+ -- Return parsed fields
+ return true, {
+ password = password;
+ public_id = prefix;
+ token = token;
+ private_id = bin2hex(uid);
+ session_counter = session_ctr;
+ use_counter = use_ctr;
+ timestamp = timestamp;
+ };
+end
+
+function _M.new_authenticator(config)
+ local parser = _M.new_otp_parser(config);
+ local function authenticate(self, otp, key, device_info, userdata)
+ -- Parse OTP, get device data (from config callback)
+ local ok, ret = parser:parse(otp, key);
+ if not ok then return ok, ret; end
+
+ if not device_info then
+ device_info = config.fetch_device_info(ret);
+ end
+
+ if ret.use_counter < (device_info.use_counter or 0)
+ or ((ret.use_counter == (device_info.use_counter or 0))
+ and (ret.session_counter <= (device_info.session_counter or 0))) then
+ return false, "otp-already-used";
+ end
+
+ local authed, err = config.check_credentials(ret, device_info, userdata);
+ if not authed then return authed, err; end
+
+ device_info.use_counter = ret.use_counter;
+ device_info.session_counter = ret.session_counter;
+
+ config.store_device_info(device_info, userdata);
+
+ return true, ret;
+ end
+ return { authenticate = authenticate };
+end
+
+return _M;