It shouldn’t surprise that encryption is essential in today’s digital age. But what exactly is encryption? How can you determine what type of encryption you need? If you asked someone to specify the type of encryption they use, they might respond with full-disk encryption. They may also mention an encryption-based protocol like HTTPS (HyperText Transport Protocol Over SSL). But encryption is more complicated than that. Encryption is a topic that I often find the most difficult to explain to even experienced technicians when I teach security classes. My goal is to help you understand the secrets of Cryptography or Secret Writing.
Many of us find it difficult to understand mathematical ciphers. While I don’t pretend to be a brilliant mathematician, I will admit that it is not my forte. Although the core algorithms are still a mystery to my, I will be the first to admit that I can still benefit from this amazing process without having to learn advanced mathematics. It is enough to understand the function of three types of mathematical ciphers: Asymmetric, Symmetric and Hashing. It is easier to understand the reasons and how we use each category.
To keep data secret, Symmetric ciphers can be used. Although it sounds simple, you will understand the differences between the two types of ciphers. Let me be more specific. Symmetric ciphers can be used to store and transmit secret data with the intention of later reading it. This means that we must be able decrypt it using a key. It is symmetric because the same key is used for both encryption and decryption.
It’s like a lockbox. I have a secret message to you. I put it in a container and locked it with a key. I then handed you the box so that you could open it. You will also need the key. This is actually one of the most difficult problems with symmetric cryptography. How can you create a lockbox with its key, then share it with others without the key being stolen? We’ll get to that in a moment.
Symmetric ciphers can encrypt any size message with minimal effort. This is why we use them to encrypt files and e-mails. It is also used for wireless encryption and encrypted data over the internet. Key storage is also an issue with symmetric encryption. How do I protect my key from being stolen and accessed by others? We’ll be addressing distribution today but will save the storage discussion for later.
Answer to the distribution question is a second type of encryption: asymmetric encryption. Asymmetric encryption should be obvious if symmetric is the same key that unlocks and locks it. If the key was used for locking it, a new key will be required to unlock it. This pair of keys is called private/public key pairs. The public key can be shared with anyone who requests it, but the private keys should be kept private. Both keys can be locked but must be used to unlock the other. Asymmetric ciphers are limited in their ability to encrypt small amounts of data. They cannot be used to encrypt secret messages. Asymmetric ciphers are usually only used for two purposes.
The first is key distribution. I have a secret message that is encrypted using a symmetric encryption. I need to share this message with you, but don’t have your key. I can lock the session key with your public key if I get your key. Only your private key can unlock it. The public key can only be used to lock the session key in this scenario. You would then be able unlock my secret message once you have unlocked the session key. This all supports confidentiality, a security concept.