/*
* Tries to login with the given cookie as credentials
*/
static void LoginFromCookie(HttpCookie cookie, ApplicationContext context)
{
// User has persistent cookie associated with client
var cookieSplits = cookie.Value.Split(' ');
if (cookieSplits.Length != 2)
{
throw new SecurityException("Cookie not accepted");
}
// Retrieving username and (hashed/salted) password from cookie.
var cookieUsername = cookieSplits [0];
var cookiePassword = cookieSplits [1];
// Retrieving password file in Node format.
var pwdFile = AuthFile.GetAuthFile(context);
// Checking if user exist.
var userNode = pwdFile ["users"] [cookieUsername];
if (userNode == null)
{
throw new SecurityException("Cookie not accepted");
}
/*
* Checking if user's password is a match.
*
* Notice, we need to double hash the password from "auth", since the
* reference stored in cookie is double hashed, and has the client's fingerprint
* added to it, to reduce probability of cookie theft.
*
* Notice also that since the credential cookie has roughly 1.0e+77 amount of
* entropy, slow hashing or using blow fish at this point is pointless, and
* would simply add additional overhead for the initial loading of our page
* when the persistent credential cookie needs to be verified. Hence we
* can safely get away with "fast hashing" at this point, but adding parts
* of the clients fingerprint into the mix, to avoid at least to some extent
* credential cookie theft.
*/
if (cookiePassword == Passwords.HashPasswordForCookieStorage(
context,
userNode ["password"].Get <string> (context)))
{
// MATCH, discarding previous Context Ticket and creating a new Ticket.
SetTicket(context, new ContextTicket(userNode.Name, userNode ["role"].Get <string> (context), false));
// Evaluates user's [.onlogin] section, if it exists.
EvaluateOnLoginIfExisting(context);
}
else
{
// Catched above, which destroys cookie, and associates the default context with user.
throw new Exception();
}
}
/*
* Tries to login user according to given user credentials.
*/
public static void Login(ApplicationContext context, Node args)
{
// Defaulting result of Active Event to unsuccessful.
args.Value = false;
// Retrieving supplied credentials.
var username = args.GetExChildValue <string> ("username", context);
var password = args.GetExChildValue <string> ("password", context);
args.FindOrInsert("password").Value = "xxx"; // In case an exception occurs.
var persist = args.GetExChildValue("persist", context, false);
// Retrieving password file as a Node.
var pwdFile = AuthFile.GetAuthFile(context);
/*
* Checking for match on specified username.
*/
var userNode = pwdFile ["users"] [username];
if (userNode == null)
{
// Username doesn't exist.
throw new LambdaSecurityException(_credentialsNotAcceptedException, args, context);
}
/*
* Checking if current username has attempted to login just recently, and the
* configured timespan for each successive login attempt per user, has not passed.
*
* This should be able to provide some rudimentary defense from a "brute force password attack".
*
* Notice, we do this after we have checked if the username exists, to avoid having an adversary
* flood the server's cache with bogus usernames associated with DateTime objects.
* We also us the web cache, which (of course) means the object will only exists for some
* time, defaulting to the settings of the web cache for your system.
*/
var cooldown = context.RaiseEvent(
".p5.config.get",
new Node(".p5.config.get", _cooldownPeriodConfigName)) [0]?.Get(context, -1) ?? -1;
if (cooldown != -1)
{
// User has configured the system to have a "cooldown period" for successive login attempts.
var bruteForceLastAttempt = new Node(".p5.web.cache.get", _bruteForceCacheName + username);
var lastAttemptNode = context.RaiseEvent(".p5.web.cache.get", bruteForceLastAttempt);
if (lastAttemptNode.Count > 0)
{
// Previous attempt has been attempted recently.
var date = lastAttemptNode [0].Get <DateTime> (context, DateTime.MinValue);
var timeSpanSeconds = Convert.ToInt32((DateTime.Now - date).TotalSeconds);
if (timeSpanSeconds < cooldown)
{
// Cooldown period has not passed.
throw new LambdaException("You need to wait " + (cooldown - timeSpanSeconds) + " seconds before you can try again", args, context);
}
}
}
// Checking for match on password.
if (!Passwords.VerifyPasswordIsCorrect(password, userNode ["password"].Get <string> (context)))
{
/*
* Making sure we guard against brute force password attacks, before we throw security exception.
*
* Notice, this prevents the same username from attempting to login more than once every n seconds,
* which is configurable in the config file of the app.
*/
var bruteForceLastAttempt = new Node(".p5.web.cache.set", _bruteForceCacheName + username);
bruteForceLastAttempt.Add("src", DateTime.Now);
context.RaiseEvent(".p5.web.cache.set", bruteForceLastAttempt);
throw new LambdaSecurityException(_credentialsNotAcceptedException, args, context);
}
// Success, creating our context ticket.
var role = userNode ["role"].Get <string> (context);
SetTicket(context, new ContextTicket(username, role, false));
// Signaling success to caller.
args.Value = true;
// Checking if we should create persistent cookie on disc to remember username/password for given client.
if (persist)
{
// Caller wants to create persistent cookie to remember username/password.
var cookie = new HttpCookie(_credentialCookieName);
cookie.Expires = DateTime.Now.AddDays(context.RaiseEvent(
".p5.config.get",
new Node(".p5.config.get", "p5.auth.credential-cookie-valid")) [0].Get <int> (context));
// To avoid JavaScript access to credential cookie.
cookie.HttpOnly = true;
/*
* The value of our cookie is in "username hashed-password" format.
*
* This is an entropy of roughly 1.1579e+77, making a brute force attack
* impossible, at least without a Rainbow/Dictionary attack, which should
* be effectively prevented, by having a single static server salt,
* which again is cryptographically secured and persisted to disc
* in the "auth" file, and hence normally inaccessible for an adversary.
*
* Notice, we double hash the password we store in our cookie, to make
* sure we never expose the parts of our password we store in our "auth" file.
*/
cookie.Value = username + " " + Passwords.HashPasswordForCookieStorage(
context,
userNode ["password"].Get <string> (context));
HttpContext.Current.Response.Cookies.Add(cookie);
}
// Evaluates user's [.onlogin] section, if it exists.
EvaluateOnLoginIfExisting(context);
}
