Week2.pdf

Cryptography Basics An Introduction to Cryptography, Symmetric and Asymmetric Encryption, and Key Management Table of Contents 1.Introduction to Cryptography 2.Symmetric Encryption 3.Asymmetric Encryption 4.Key Management Introduction to Cryptography Definition of Cryptography The p...

Cryptography Basics An Introduction to Cryptography, Symmetric and Asymmetric Encryption, and Key Management Table of Contents 1.Introduction to Cryptography 2.Symmetric Encryption 3.Asymmetric Encryption 4.Key Management Introduction to Cryptography Definition of Cryptography The practice and study of techniques for securing communication and data in the presence of adversaries. History of Cryptography Ancient Egypt: Hieroglyphs Caesar Cipher World War II: Enigma Machine Modern Cryptography Computer and network security History of Cryptography Hieroglyphs is the writing system ancient Egyptians used for inscriptions mostly on walls of temples and tombs, as well as statues, coffins. These were created for eternity, either for the gods or for the afterlife. History of Cryptography It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet. History of Cryptography The Enigma machine is a cipher device developed and used in the early- to mid-20th century to protect commercial, diplomatic, and military communication. Goals of Cryptography Confidentiality Ensuring that information is accessible only to those authorized to have access. Integrity Ensuring that information is accurate and unaltered. Authentication Verifying the identity of a person or entity. Non-repudiation Assurance that someone cannot deny the validity of something. Symmetric Encryption Definition Encryption method where the same key is used for both encryption and decryption. Examples AES (Advanced Encryption Standard) DES (Data Encryption Standard) Advantages Fast and efficient Disadvantages Key distribution problem How Symmetric Encryption Works Encryption Process Plaintext is converted to ciphertext using an encryption key. Decryption Process Ciphertext is converted back to plaintext using the same key. How Symmetric Encryption Works Sample Code: Asymmetric Encryption Definition Encryption method where two different keys are used: a public key and a private key. Examples RSA (Rivest-Shamir-Adleman) ECC (Elliptic Curve Cryptography) Advantages Solves the key distribution problem Disadvantages Slower compared to symmetric encryption How Asymmetric Encryption Works Encryption Process Public key is used to encrypt the message. Decryption Process Private key is used to decrypt the message. How Asymmetric Encryption Works Explanation 1.Key Generation: 1. rsa.generate_private_key generates a private key. The public key is derived from this private key. 2. The public_exponent is typically set to 65537 for security and efficiency reasons. 3. The key_size determines the strength of the encryption. A size of 2048 bits is common for secure RSA encryption. 2.Message Encryption: 1. The public_key.encrypt method encrypts the message using the public key and OAEP padding with SHA-256 hashing. OAEP (Optimal Asymmetric Encryption Padding) is a padding scheme often used with RSA encryption to provide semantic security. 3.Message Decryption: 1. The private_key.decrypt method decrypts the ciphertext using the private key and the same OAEP padding scheme used for encryption. Key Management Definition The process of managing cryptographic keys in a cryptosystem. Key Generation Creating cryptographic keys. Key Distribution Securely distributing keys to parties. Key Storage Securely storing keys to prevent unauthorized access. Key Management Challenges Key Distribution Ensuring keys are delivered securely. Key Storage Protecting keys from theft or loss. Key Rotation Regularly updating keys to maintain security. Key Revocation Removing keys that are no longer secure. Best Practices in Key Management Use Strong Keys Choose keys with sufficient length and complexity. Implement Key Rotation Regularly change keys to limit exposure. Secure Key Storage Use hardware security modules (HSMs) for storing keys. Access Controls Limit access to keys based on the principle of least privilege.