To make data unreadable to others, it is encrypted using cryptography. Data that is available in plaintext is converted to encrypted data (ciphertext) and made unreadable.
Only the person or entity with the correct decryption key can decrypt the data and make it readable again.
There are two common types of encryption: symmetric encryption and asymmetric encryption.
Symmetric encryption, also known as one-key encryption, uses a single secret key to encrypt and decrypt the data. This means that the entities must agree on a common key in advance and exchange it with each other. The danger here is that a third party can gain access to this key and then decrypt and read the encrypted data. They can also send encrypted data themselves without being detected.
This is where asymmetric encryption comes in. The plaintext itself is encrypted using symmetric encryption, and the key is then protected using asymmetric encryption.
The advantage of symmetric encryption is that it is quick and easy to set up and has a high encryption and decryption speed. In addition, the security can be influenced by the key length, and as the key size increases, it grows exponentially in terms of possible combinations.
A disadvantage is the number of keys, which grows quadratically with the number of entities. With two entities there is only one key, with three there are three keys, and with four there are six keys. The second is the key exchange. If a decryption key falls into the wrong hands, all communication is exposed.
Well-known symmetric encryption algorithms include AES (Advanced Encryption Standard), which we use at Engity. Other algorithms include Blowfish and its successor Twofish, as well as IDEA (International Data Encryption Algorithm).