Understanding Encryption! | ICT #9

Introduction to Encryption and Decryption

In this section, we are introduced to the concepts of encryption and decryption, their importance, and their role in secure communication.

What is encryption and why is it needed?

• Encryption is the process of transforming plain text into cipher text.

• It ensures that only the intended recipient can decrypt and read the message.

• Encryption is crucial for secure communication and protecting sensitive information.

How do messages travel through the internet?

• Messages travel through various internet service providers (ISPs) and network service providers (NSPs).

• Data travels in packets and can take different paths through routers to reach its destination.

• Generally, ISPs or NSPs are assumed not to eavesdrop on communications.

Importance of secure communication

• When connecting to public Wi-Fi hotspots, it's important to ensure that our browsing activities are not visible to others.

• The prefix "HTTPS" in URL addresses indicates a secure communication protocol.

• Secure communication prevents access point providers from seeing login credentials or viewed pages.

Symmetric and Asymmetric Encryption

This section explains symmetric and asymmetric encryption methods used for secure data transfer.

Symmetric encryption

• In symmetrical encryption, the same key is used for both locking (encryption) and unlocking (decryption).

• The sender shares the key with the receiver securely before transferring data.

Asymmetric encryption

• Asymmetrical encryption uses different keys for locking (public key) and unlocking (private key).

• The public key can be shared openly, while the private key remains secret.

• Only the corresponding private key can unlock data encrypted with a specific public key.

Key distribution center

• A responsible entity called a key distribution center facilitates secure transfer of keys between sender and receiver.

Secure Data Transfer

This section explains how secure data transfer is achieved using encryption and decryption.

Process of secure data transfer

• When sending a message, the sender requests the recipient's public key from the key distribution center.

• The sender encrypts the message using the recipient's public key.

• Only the recipient, with their private key, can decrypt and read the message.

Importance of prime numbers in encryption

• The keys used in encryption are derived from the product of two prime numbers.

• Prime numbers play a crucial role in ensuring secure encryption algorithms.

RSA algorithm

• The RSA algorithm is a popular method that uses two prime numbers to generate private and public keys for encryption and decryption.

Explanation of the Algorithm

The video explains that a detailed explanation of the algorithm is beyond its scope.

Why Use Prime Numbers?

• The process of finding factors of a number is called factorization.

• Hackers use brute force methods to factorize numbers and find the private key.

• Factorization works faster with non-prime factors, but slower with prime factors.

• RSA algorithm becomes difficult to crack when prime numbers are large.

Asymmetric Encryption vs Symmetric Encryption

• Asymmetric encryption, like public-private key cryptography, has not replaced symmetric encryption methods.

• Asymmetric encryption is computationally intensive and can cause time delays in data exchange.

• Symmetric encryption systems like Advanced Encryption Standard (AES) are used as a remedy for this problem.

• In such systems, a session key is exchanged as the first message and used for further data exchange.

Session Key and Updates

This section discusses session keys and their updates in communication protocols.

Session Key Usage

• A session key is frequently updated based on the communication protocol used.

• In WhatsApp, a new session key is generated for every message.

• In HTTPS, the session key may be valid for a certain period or until the session ends.

Public Private Key Authentication

This section explains how public-private key cryptography allows message authentication.

Authenticating Messages

• Public-private key approach enables message authentication.

• Nina encrypts the message with her private key to ensure authenticity.

• Alex can decrypt the message using Nina's public key and verify it came from her.