CMPUT 404

Web Applications and Architecture

Authentication

Created by
Abram Hindle (abram.hindle@ualberta.ca)
and Hazel Campbell (hazel.campbell@ualberta.ca).
Copyright 2014-2023.

Web Authentication

• Authentication methods supported by Web Standards

HTTP Basic Auth

• Created by Ari Luotonen in 1993.
• Username and password not hidden by HTTP
• You must use another encryption layer (TLS) below HTTP (HTTPS) for security!

HTTP Basic Auth

• Easiest to implement
• Stateless
• Response: 401 Unauthorized & WWW-Authenticate: Basic header.
• Request: Authorization: Basic header

HTTP Basic Auth

• The username and password are encoded but not encrypted

function encodeBasic(username, password) {
    utf8bytes = new TextEncoder().encode(username + ":" + password);
    binaryString = String.fromCodePoint(...utf8bytes);
    return btoa(binaryString);
}
function decodeBasic(base64String) {
    binaryString = atob(base64String);
    utf8bytes = Uint8Array.from(binaryString, (c) => c.codePointAt(0));
    both = new TextDecoder().decode(utf8bytes);
    seperator = both.indexOf(':');
    return [both.slice(0,seperator), both.slice(seperator+1)];
}

HTTP Basic Auth

• Cannot customize username/password prompt
• Browser will remember to keep sending auth
• All files an subdirs at or below will be considered authenticated
  • If we authenticate at /stuff/private/index.html:
  • /stuff/private/1 browser will assume is authenticated
  • /stuff/private/folder/banana.html browser will assume is authenticated

HTTP Basic Authentication

HTTP Digest Auth

• Defined in RFC 2069, Franks et al, 1997.
• Uses cryptographic hashes, designed to hide username & password...
  • But it uses MD5 which is broken.
  • Secure SHA-256 hash added only in 2021 (firefox) and 2023 (chrome)
• So... You must use another encryption layer (TLS) below HTTP (HTTPS) for security!
• Not really used...

HTTP Digest Auth

• Doesn't prevent tampering with content, headers, paths, ...
• Just use TLS!

Session Cookie Authentication

Signed Token Authentication

Signed Token Authentication

• Response: 401 Unauthorized & WWW-Authenticate: Bearer header.
• Request: Authorization: Bearer header
• Can use Set-Cookie and Cookie to transfer token
  • But... it can be tripped up by CORS rules!
  • Access-Control-Allow-Origin: and friends.

JSON Web Tokens

{
    "alg": "HS256",
    "typ": "JWT"
}{
    "sub": "user_id=1234567890",
    "custom": "whatever",
    "iat": 1698689742
}

• Base64 Encoded + "." + Base64 cryptographic signature

JWT Demo

The OAuths

• Allows a user to tell authorization server it's ok to allow a client (which can be a server) to access resource server API on their behalf.
• Example: User allows their email application to access gmail on their behalf.
  • Client: email application
  • Authorization server: accounts.google.com
  • Resource server: gmail.com

The OAuths

• Allows a user to tell authorization server it's ok to allow a client (which can be a server) to access resource server API on their behalf.
• Example: User allows their email application to access gmail on their behalf.
  • Client: super powered mail manager service $100/month guaranteed success (also a website/server, actually)
  • Authorization server: accounts.google.com
  • Resource server: gmail.com

OAuth 1

OAuth 2

OAuth 1 vs 2

OpenID Connect

1. Do OAuth 2.0
   • The site you are logging into is the client, AKA Relying Party (RP).
   • The site you are logging in with is the authorization server and resource server, AKA Identity Provider (IDP).
2. Use OAuth 2.0 authorization to get a JWT from the IDP, which we then give to the RP as proof of who we are.
   • The thing we are AUTHORIZING the client/RP to do is request information about who we are, according to the IDP/authorization server.

OpenID Connect

SAML

• Like OpenID Connect but doesn't use OAuth or JWT, instead uses XML and its own thing
• Mostly used by academic institutions (such as the Unversity of Alberta)

Cookie: vs Authorization: Bearer

• Both headers sent by the client

License

Copyright 2014-2023 ⓒ Abram Hindle

Copyright 2019-2023 ⓒ Hazel Victoria Campbell and contributors

Other images used under fair use and copyright their copyright holders.

License

Copyright (C) 2019-2023 Hazel Victoria Campbell
Copyright (C) 2014-2023 Abram Hindle and contributors

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN.

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