In this article I explain the concept of encryption. After addressing some common terms, the process of encryption itself is explained through a basic example. Then different types of encryption used today are discussed. At the end there is a summary.
Encryption is making information you want to store or send unreadable for an unintended party. By using an algorithm the information is scrambled and made unreadable. Later on this process is reversed through decryption to retrieve the original information.
Plaintext and Ciphertext
The information to be encrypted is called the plaintext. The plaintext is information you want to secure, because it often contains sensitive material. This can be a text message or any other data you want to keep hidden. The result of encryption is called the ciphertext. Ciphertext looks random and in itself doesn’t/shouldn’t say anything about the plaintext.
How Does Encryption Work?
The plaintext or data is scrambled through a predefined set of steps, an algorithm. A key or multiple keys are established, which are needed to encrypt and decrypt the data. It’s like a physicial key used to lock and unlock a physical lock. Using a key or multiple keys to encrypt and decrypt plaintext is still the underlying concept of encryption algorithms today.
Below you can find a very simple example of an encryption algorithm, a transposition algorithm. In a transposition algorithm, the plaintext is divided into blocks, then the blocks are shuffled. The transposition algorithm has different variations. A simple variation of a transposition algorithm is columnar transposition. In columnar transposition the plaintext is put into columns like below, which form the “blocks”. Then the blocks or columns are shuffled.
The key to encrypt and decrypt the plaintext is the length of the rows and the order in which the columns are shuffled. As you can see above these are 7 and (3, 5, 1, 7, 2, 4, 6). The result of this key applied to the message:
"THIS IS A RANDOM MESSAGE TO BE ENCRYPTED TODAY"
Encryption Methods Used Today
The most common encryption methods used today are symmetric and asymmetric encryption.
With symmetric encryption the sender and receiver of information have the same key which they use to both encrypt and decrypt information. It is important to keep the key secret. A common symmetric algorithm is AES. The challenge of symmetric encryption is the establishment of the key. The key has to be established in a way that no outside party intercepts it. The interception of the key makes the decryption of the plaintext by outside parties possible.
Asymmetric encryption is requires the sender and receiver to each have two keys. One public key and one private key. To encrypt information the sender has to use his private key aswell as the public key of the receiver. The public key is accessible by anyone and not kept secret, which you wouldn’t expect when you are trying to secure information. Although the public key is accessible by anyone, asymmetric encryption is generaly speaking more secure. A problem is that it is slower compared to symmetric encryption and this can have a negative affect on performance. The most common asymmetric encryption algorithm is RSA.
- Encryption is applying an algorithm to information with the intention of making it unreadable for outside parties.
- The information to be encrypted is called the plaintext, the unreadable result is called the ciphertext.
- Symmetric encryption uses a single key to encrypt and decrypt plaintext.
- A challenge of symmetric encryption is establishing a secret key.
- Asymmetric encryption uses both a private key and a public key to encrypt and decrypt ciphertext.
- A disadvantage of asymmetric encryption is the possible negative affect on performance.