Fundamental of Cryptography

FUNDAMENTAL OF CRYPTOGRAPHY

Cryptography is the science of securing information by transforming it into an unreadable format (encryption) to ensure confidentiality, integrity, authentication, and non-repudiation.

Goals of Cryptography

Cryptography serves the following primary purposes:

1. Confidentiality: Ensuring that information is only accessible to authorized parties.
2. Integrity: Verifying that information has not been altered or tampered with.
3. Authentication: Confirming the identity of the parties involved in communication.
4. Non-repudiation: Ensuring that a sender cannot deny having sent a message.

Concepts in Cryptography

Encryption and Decryption

• Encryption: The process of converting plaintext (readable data) into ciphertext (unreadable data) using an algorithm and a key.
• Decryption: The process of converting ciphertext back into plaintext using a key.

Keys

• A key is a secret piece of information used in the encryption and decryption processes.
• Key types:
  • Symmetric Key: The same key is used for both encryption and decryption.
  • Asymmetric Key: A pair of keys (public and private) is used. The public key encrypts data, and the private key decrypts it.

Cryptographic Algorithms

Cryptographic algorithms define the process of encryption and decryption. There are two main types:

1. Symmetric Encryption: Uses a single shared key.
2. Asymmetric Encryption: Uses a pair of keys (public and private).