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  • John Bell

Tech Sense: Encryption

Updated: Sep 27, 2023


One way of protecting your data involves a technology known as encryption. When you were a child, you may have owned a toy known as a “secret encoder ring” sometimes found in cereal boxes. These rings provide a very simple form of encryption by scrambling the alphabet substituting each letter for another. A message written using the code would appear as a jumbled mess. To read the message, decrypt it by using the ring in reverse to restore the original text.

Today’s encryption technologies are more sophisticated. The current standard is the Advances Encryption Standard, better known as AES. Today, there is no known way of decrypting a message that has been properly encrypted with AES without knowledge of the key used to encrypt the data.

Most current encryption algorithms use keys as the material to initialize the encryption process. The longer the key, the more secure the message. The strongest form of AES uses a 256 bit key. AES is a symmetric encryption algorithm. This means the same key is used to encrypt and to decrypt the data. An asymmetric encryption algorithm has two keys, one for encryption and another for decryption. Often one key is designated as the public key, which can be shared with anyone, and the other is the private key, which must be protected by the owner.

Cryptography examples often use Alice and Bob as two typical users that want to securely exchange a message protecting the message from a third party know as Eve. To show the value of asymmetric encryption, let’s assume that Alice and Bob have no secure means of exchanging a symmetric key but both have their own public key and matching private key. Bob and Alice share the public keys with each other and everyone else including Eve. Bob then encrypts a message using his private key to send to Alice. He then encrypts the encrypted message again but this time using Alice’s public key. He now sends the twice encrypted message, and it is received by both Alice and Eve. Alice uses her private key to decrypt the message Bob encrypted with her public key. This gives her the message Bob encrypted with his private key. Alice then uses Bob’s public key to decrypt the message giving her the original message Bob sent (also called the plain text message). Eve is not able to access any information because she does not have Alice’s private key.

Frequently, the first message sent between Bob and Alice is a shared key that can be used for symmetric encryption using a shared secret (key) between the two of them. This is important because symmetric encryption is faster the asymmetric encryption. The infrastructure that supports this for the web is called Public Key Infrastructure or PKI. The HTTPS protocol uses encryption to securely connect a browser to a website works in the same fashion.

In response to the revelation that numerous governments are monitoring web traffic globally, the web has created the HTTPS Everywhere initiative encouraging every website to support the secure HTTPS protocols. Use HTTPS to connect to websites to protect yourself from whoever may be listening.

That’s it for this month. Next month, I will share some tools that can be used to encrypt and protect your documents and communications.

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