Namaste Yogis. Welcome to the Blockchain & AI Forum, where your technology questions are answered, mostly correct! Here no question is too mundane. As a bonus, a proverb is also included. Today’s question, was submitted by William from La Puente, CA and he wants to know what is cryptography?
William, you came to the right place. William the only reasonable place to start is with a definition. Let me answer by referring to an awesome movie called My Big Fat Greek Wedding. In the movie the father of the bride would constantly say, “… the Greeks invented that, the Greeks did that first, etc.” Well perhaps the old man had a point because in the case of cryptography the word comes from the Greeks. Kryptos means hidden and graphein is to write; hence, cryptograph is to write in a hidden manner. Holy hidden message, Batman!
Okay the word has its origin in Greece, but what does cryptography do? Essentially, cryptography provides information protection/security. Using cryptography, data can be transformed by substitution. For example, an early and primitive form of substitution cryptography was to shift every letter three spots. A sentence that would normally read like this: “Encrypted using Caesar cipher” becomes Hqfubswhg xvlqj Fdhvdu fiskhu. The other method, known as transposition, involves moving the order of characters of words by a pre-determined agreement. No, it’s not pig Latin! Lol.
Cryptography concepts are likely foreign; hence, we should start slowly. I’ll cover just three topics today and save the rest for later. Let’s start with the security services of cryptography, there are four.
First is authentication. By authentication I mean the assurance the communicating entity is legitimate. Second, data confidentiality. In other words, the protection from unauthorized disclosure. The third is data integrity. In this context I mean the data has not been altered; it was received exactly as sent. Last, comes non-reputation. Non-reputation refers to the notion that the receiver can prove the alleged sender sent the message. Impressive!
We are off to a fast start. Let’s try two more topics beginning with cryptographic keys.
In cryptography there are two types of key systems–symmetric and asymmetric. Symmetric is where one key is used to encrypt and decrypt messages. The keys are essentially shared by the two parties and the data is transferred via a secure network. However, authentication nor non-reputation is provided, and the origin of the message cannot be determined. Let’s compare that to asymmetric cryptography.
In asymmetric there are public and private keys. The public key is derived from the private. As you can guess, asymmetric was developed due to the problems with symmetric cryptography. Asymmetric wins the crypto security battle handily. However, if you lose your private key there is no way to access the data, value, or information that was sent! You best hold on tight!
Hashing is an ideal spot to end the lesson. Hashing, (I don’t mean potatoes, although I love hash browns) in cryptography is the process of transforming data or a string of characters into a short and fixed length value. The value produced is unique; no other record has it. Hashing algorithms are used to perform the hashing process in three steps: 1) data input; 2) hashing function #; and 3) hash output (of a fixed length). By the way, blockchains make extensive use of hashing. More on that later.
There is more to say but for now I’ll stop with a proverb from our friends in Tajikistan, where they say: In every drop of water, there is a grain of gold.
Until next time,
Yogi Nelson
Blockchain & AI Forum 