INTECH 3201 - Cryptography and Encryption

Cryptography and Encryption

Cryptography

The art of communication between two users via coded messages

Encryption

The process of scrambling data into a code that can only be decoded with a key.

Plaintext

The original representation of the information

Ciphertext

The encoded version of the information

Encryption key

A unique digital key that unlocks the code

Decryption

The process of turning ciphertext back into plaintext

earliest written evidence of encryption can be traced to ancient ___. Nearly ____ years ago

Egypt, 4’000

tomb of nobleman ____ contained a script recording his deeds in life (ENCRYPTED)

Khnumhotep II

Ancient encryption in Egypt was used mainly to ______, as education was a privilege limited to the highest circles of society and was also a way to show one’s skills in writing. It was also used for religious reasons, for example, to discuss taboos.

protect knowledge

The first recorded instance of encryption being used for military purposes dates to around ____ BC

500

scytale

Spartan encryption used an invention called the ______, which allowed secret messages to be sent and received.

common key

first time the concept of a ____, seen even today in modern cryptographic technologies, was used for both encryption and decryption.

Caesar Shift Cipher

World War II (ENIGMA)

World War II (ENIGMA)

has an electromechanical rotor mechanism that scrambles the 26 letters of the alphabet.

When did data encryption become popular?

Through the early 1970s, cryptology was dominated by governments both because computers were very expensive and because of the need for information retention.

RSA algorithm (named after its inventors ______, ______, __________)

Ron Rivest, Adi Shamir, and Leonard Adleman

RSA introduced the concept of a __________ for encryption

public-private key pair

Confidentiality

Integrity

Authentication

Non-repudiation

Key management

Cryptography - Principles

Confidentiality

Cryptography - Principles - The main idea of Confidentiality is to keep data safe so that information stays private and secure

Cryptography - Principles -

Integrity means ensuring that our data in transit or after receiving is intact or not.

It is the ability to make sure that data or information has not been changed or modified with.

Integrity

Cryptography - Principles -

Authentication is the process of validating the identity of a user or device. Cryptographic methods, like digital signatures, can be used to securely verify the identification of a person or device.

Authentication

Cryptography - Principles -

___________ is a method of stopping a person from denying that he or she has committed a particular act or crime.

Non-repudiation

Cryptography - Principles -

Key management is the process of creating, distributing, and managing cryptographic keys

Key Management

2 main type of cryptographic systems

Symmetric

Asymmetric

Symmetric Encryption

________ uses a single key for both encryption and decryption. The sender and receiver must share this key securely.

How symmetric encryption works?

▪ The sender encrypts the plaintext using a secret key and an encryption algorithm (e.g., AES). ▪ The encrypted ciphertext is sent to the receiver. ▪ The receiver decrypts the ciphertext using the same secret key to retrieve the original plaintext.

Examples of Symmetric Encryption Algorithms

▪ Data Encryption Standard (DES) – A 56-bit key encryption method, now considered weak.

▪ Triple DES (3DES) – An improved version of DES that applies encryption three times. ▪ Advanced Encryption Standard

▪ (AES) – A widely used and highly secure algorithm with key sizes of 128, 192, or 256 bits.

Advantages of Symmetric Encryption

Fast and efficient (suitable for large amounts of data).

Requires less computational power compared to asymmetric encryption.

Disadvantages of Symmetric Encryption

Key distribution is a challenge—if the key is intercepted, security is compromised. Not ideal for secure communication between unknown parties.

Asymmetric Encryption

______, also known as public-key cryptography, uses two keys: Public Key (used for encryption) Private Key (used for decryption)

Asymmetric Encryption

type of encryption where The public key is shared openly, while the private key is kept secret.

How asymmetric encryption works?

The sender encrypts the plaintext using the recipient’s public key. ▪ The encrypted message (ciphertext) is sent to the receiver. ▪ The receiver decrypts the ciphertext using t

Rivest-Shamir-Adleman (RSA) – A widely used encryption algorithm, often used for securing online transactions and emails.

Elliptic Curve Cryptography (ECC) – A more efficient alternative to RSA, used in mobile and IoT security.

Examples of Asymmetric Encryption Algorithms

Rivest-Shamir-Adleman (RSA) – A widely used encryption algorithm, often used for securing online transactions and emails.

Elliptic Curve Cryptography (ECC) – A more efficient alternative to RSA, used in mobile and IoT security.

Advantages of Asymmetric Encryption

Disadvantages of Asymmetric Encryption

Slower than symmetric encryption due to complex computations.

Requires more computational power.

Real-World Use Case

Real-World Use Case