Ethical Hacking - Cryptography

Cryptography means the study of encryption and encryption algorithms. Encryption is the conversion of messages from a comprehensible form (clear text) into an incomprehensible one (cipher text), and back again (decryption). The purpose of encryption is to attempts secure communications.

Types of Cryptography : Cryptography involves the use of an algorithm and a key. The key is usually preshared between the parties involved in the communication. Based on the type of key being used for encryption and decryption, there are two types of encryption.

Symmetric Encryption : In symmetric key encryption the same key is used for both encryption and decryption. The parties involved in this must have access to the encryption key. It works faster than asymmetric encryption and is simple to implement. However, the major risk is the encryption key being leaked or compromised. If the encryption key is stolen by any means, then any person possessing that key will be able to encrypt and decrypt data in an unauthorized manner.

Asymmetric Encryption : Asymmetric encryption overcomes the security concern with using symmetric encryption. Asymmetric encryption uses separate keys for encryption and decryption. The key used for encrypting the data is referred to as the public key , while the key used for decrypting the data is referred to as the private key . Although this makes the process a bit more complex and slower than symmetric encryption, it certainly offers better protection against the risk of keys being compromised. Asymmetric encryption is also known as public-key cryptography.

To understand how asymmetric encryption works, consider the following example, in which A wants to send some confidential data to B using asymmetric encryption :

(a) A will use B’s public key to encrypt the data to be sent.
(b) A will send the encrypted data to B.
(c) B will use his own private key to decrypt the data sent by A.