Angular - Chapter 9 - Authentication and Authorization

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Authentication and Authorization
Angular

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Introduction
(Security Foundations)

Introduction
• Authentication is the process of validating a user on the credentials (username and password)
and provide access to the web application(ex: Email)
• Authorization helps you to control access rights by granting or denying specific permissions
to an authenticated user (Ex: User / Manager / Admin).
• Authorization is applied after the user is authenticated. Typically users are assigned with rights /
permissions based on which appropriate section(s) are loaded in the web application
• The user interacts with the server on Authorized sections of the application which results in data
exchange. In order to protect security and integrity of data other security components (ex:
Encryption) comes into picture

Introduction
• Security is an inherent and critical feature of a web application. With rich data available
in the web server, any compromise results in bigger issues in socio / political ecosystem
• There are many algorithms, standards and tools in security which is quite vast in nature
• Our idea is to understand security from Angular Authentication and Authorization perspective
by practically implementing them in front-end web applications
• We will enhance our understanding of Routes (previous chapter) and display / hide certain
components based on the user authorization

JSON Web Tokens (JWT)
• JSON Web Token (JWT) is an open standard defined in RFC 7519.
• It is a compact and self-contained way for securely transmitting information between parties (ex:
Web client and server) as a JSON object.
• This information can be verified and trusted because it is digitally signed.
• JWTs are signed using a secret (ex: HMAC algorithm) which is only known to client & server
• The signed token ensures the data integrity and security

JSON Web Tokens (JWT) – In Action..

JSON Web Tokens (JWT) – Usage
• JWTs are used in web based authorization once the user is successfully
authenticated with valid username & password.
• Each transaction between the client after authorization are done in a secure
manner as the data is encrypted.

JSON Web Tokens (JWT) – Structure
• JWT has three parts that are separated by a (.) character
• Header, Payload and Signature (ex: xxxx.yyyy.zzzz)
• Each of them have a unique meaning and significance
• An example JWT will look as follows

JWT - Structure
• Part-I (Header): Typically consists of two parts:
• Type of the token (ex: jwt)
• Hashing algorithm used (ex: HMAC SHA256)
• Part-II (Payload): It contains claims. Claims are statements about an entity (typically, the
user) and additional data.
• Both Header & Payload are encoded using base64 encoding and made as a first and second
part of the JWT
{
"alg": "HS256",
"typ": "JWT"
}
{
"sub": "1234567890",
"name": "WSA",
"admin": true
}

JWT - Structure
• Part-III (Signature): The signature is nothing but a hash algorithm applied on header and
payload
• To create the signature part you have to take the encoded header, the encoded payload,
a secret, the algorithm specified in the header, and sign that.
• For example if you want to use the HMAC SHA256 algorithm, the signature will be created
in the following way:
HMACSHA256 (base64(header) + "." + base64(payload), secret)
• The output is three Base64 encoded strings separated by dots that can be easily passed in
HTML and HTTP environments

What is base64 Encoding? – A brief
• Base64 converts a string of bytes into a string of
ASCII characters so that they can be
safely transmitted within HTTP.
• When encoding, Base64 will divide the string of
bytes into groups of 6 bits and each
group will map to one of 64 characters.
• In case the input is not clearly divisible in 6 bits,
additional zeros are added for padding
• Similar to ASCII table a mapping table is
maintained

What is HMAC SHA? – A brief
• HMAC (Hash Message Authentication Code) - SHA
(Secure Hash Algorithm) is a specific type
of message authentication code (MAC)
• It involves a cryptographic hash function and a
secret cryptographic key. The key size can vary (ex:
SHA 256)
• The secret key is known only to the sender and the
receiver
• By applying hashing it generates what is known as
signature of the given plain text. It can be used for
validating the integrity of the message.

Exercise
• JWT Debugger tool:
• It is used to generate JWT, let us do some hands-on
• Goto https://jwt.io/#debugger and try out by generating some JWT
• Base64 Encoding tool:
• It is used to check base64 encoding, let us do some hands-on
• Goto: https://www.base64decode.org and try out some encoding

Local Storage
(Storing user data in the browser)

What is Local Storage?
• The Local storage allow to save key/value pairs
in a web browser.
• The Local storage data will persist after the
browser window is closed.
• The local storage property is read-only.
• Previously, cookies were used for storing such
key value pairs.
• Local storage has a significantly higher storage
limit (5MB vs 4KB), better for storing client
specific information

Local storage methods
Local storage supports a set of methods for dealing with the data
Method Description
setItem() Add key and value to local storage
getItem() Retrieve a value by the key
removeItem() Remove an item by key
clear() Clear all storage

Local storage methods usage
localStorage.setItem('key', 'value');
localStorage.getItem('key');
localStorage.removeItem('key');
localStorage.clear();

Starter Code
(A Brief about given code to get started with A & A)

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Angular - Chapter 9 - Authentication and Authorization

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