Introduction to Cryptography — Encryption
In this Article, I will briefly discuss Cryptography and Encryption (A cryptographic process).
Cryptography, or cryptology is the sector which deals with the secure transmission of data over network. Its a study of techniques for secure communication. There are different techniques of secure communication between two parties over a network. One of them is Encryption.
Encryption is the technique of encoding information. This process encrypts actual information (readable data) into “Cipher Text” (unreadable data) which is later decrypted by the authorized party. This enables the storage or transmission of data in a form that is unreadable thus keeping the information confidential and private.
There are basically two types of Encryption. Such as: Symmetric Encryption & Asymmetric Encryption.
In Symmetric Encryption, Confidentiality is ensured. In this method, there are mainly two components: An Algorithm and a single Key. The plain text is encrypted using the combination of these two. In practical case, we can use symmetric encryption using WinZip or 7zip. If we choose encryption option, we will be asked for a preferred algorithm and a password. After the file is encrypted, it can only be opened with the password that was used to lock it. Though it looks like only a simple file lock, it is not just a file lock. Behind the scene, the file is encrypted mathematically with the algorithm and the key. The Key is generated from the password using a method called password derivation method.
Confidentiality and Authenticity is ensured in Asymmetric Encryption. In this method, there is an Algorithm and a pair of keys (Private Key & Public Key). Public key of someone is known by all. But private key is a secret. Both party in a communication has a pair of these keys. The plain text/Information to be transmitted or stored is encrypted with the combination of the algorithm and one of the keys. Either the public or the private key. Public key is used to encrypt the readable data/plain text when we want to ensure confidentiality. On the other hand private key is used to encrypt when we want to ensure Authenticity. As an example: Alice wants to send an encrypted information to Bob using Asymmetric method. He wants confidentiality of the information. Meaning he wants only Bob to be able to open the information file. So what he needs to do is encrypt the file with Bob’s public key. Now the file can be opened only by Bob’s private key. And as the Private key is a secret, no one except Bob knows Bob’s private key. So the confidentiality is ensured. But if Alice wants to prove his authenticity, meaning he wants to assure Bob that the information is coming from no-one else but Alice himself, he needs to encrypt the file with his (Alice’s) private key. Now everyone can decrypt the information sent by Alice using Alice’s public key. So here confidentiality is not ensured but the authenticity of Alice is ensured as no-one else can have Alice’s private key except Alice.
In the next Article I will discuss the vulnerabilities of Encryption process and discuss other cryptographic methods.