Cryptography – Bits and PCs

Nothing like online currency to get people interested. So, obviously I am a few years too late to this party, but the main concepts of the technology are still relevant.

As most people know by now, the most famous application of Blockchain technology is cryptocurrency, most notably Bitcoin. But what is it? How is it better than just going to the bank and getting money, or using a bank’s online transfer system?

Essentially, anytime a transaction occurs between say, a group of 4 people, a separate “block” of memory is created for each of the 4 friends. Each block has the details of the transaction permanently inscribed on it. Imagine a group of 4 people named A, B, C, and D.

On a side note, there are currently ~400 people named ‘ABCDE’ in the continental US.

Suppose one day they all go for dinner at Olive Garden. After an evening of unlimited breadsticks, C says that he will take care of the bill for now and the others can just send in their share through Bitcoin. The next day, A,B and D all send in their transactions in a group. Everytime one of them sends money to C, a separate block is created detailing who paid whom, how much, and the reserve bitcoins left over for all the members in the group, not just the ones in the transaction. These blocks are then linked together (blockchain, super creative), and each individual is given a copy of all the blocks. This link of all the block is called a ‘public ledger’. Thus, the proof/details of the transaction is available to every single person involved.

This increases the security of the transaction as well, as there are multiple copies of the block with all of the involved persons, meaning that a single person being hacked would not be as effective as hacking someone’s bank account.

Another side note, these transactions are encrypted using different variations of the public-private key encryption that we talked about last time. Bitcoin specifically uses the SHA256 hash-key encryption system. This system allows for secure data storage, and that involved/uninvolved persons cannot meddle with the details of the transfer.

Check out this video by Simply Explained to understand more about Blockchain and how it works. Next time, we’ll look at some more history-based concepts. Until then, good luck.

Alright then, so cryptography. Cryptography is essentially the concept of secret codes, but developed to a certain point. Modern cryptography is heavily based on mathematical theory and computer science, and cryptographic algorithms are designed to be difficult to break by any opponent. Cryptography allows people to protect their information and keep it safe from potential hackers, and is invaluable for the big-tech companies of today.

Cryptography includes techniques such as microdots, merging words with images, and other ways to hide information. Today, cryptography is mainly associated with scrambling “plaintext” (just regular text) into “ciphertext”. This process is known as “encryption”, where in the text is made into secret code that can be then “decrypted” back into plain text after the data is transported to where it needs to be.

Think of cryptography as essentially a cipher, like the coded messages sent by Julius Caesar to his allies. Only a select few people with the right key to decode the cipher will be able to read the text.

I always loved the old Asterix and Obelix books, but I never really got them.

The most common and well-known method of cryptography is “public and private key” encryption done in the RSA (Rivest-Shamir-Adleman) method. This is very common over the internet, where encryption is very much necessary. Public key cryptography uses two different but mathematically similar keys, being the private key and the public key. The public key is, well, public. Anyone can see it and use it, but the private key is to remain just with you.

This public-private encryption can be simplified to a simple exchange. Say your friend wants to send you some old, embarrassing pictures. Now you have a safe that you keep empty and you realize that you can use it to keep the pictures in, so that no nosy family member can take your precious memories. But what if someone takes them while you are bringing the pictures over? You decide you can send the safe to your friend so that they can put in the pictures, and thus bring them over safely. However, you can’t trust your friend with a key to the safes’ padlock, as their siblings are very annoying and could steal it. So, what can you do?

A simple way to do it is for you to send the open, empty safe that anyone can access (the metaphorical public key) to your friend. As the safe is empty, no one will want to take it. Your friend can then put in the pictures and close down the padlock. This way, no one at their house can open it as they only have a safe and not the key. Your friend then sends the safe back, and you can use the key that you have (your metaphorical private key) to open it and secure the pictures.

Personally, I would have just stolen the safe itself.

Either way, the data that you transferred is now secure (in one way), and your embarrassing moments are long forgotten.

If you want to learn more about cryptography, check out this video by MIT OpenCourseWare detailing the RSA method. And if you want to learn about how quantum computers can break the public key encryption method, check out this video here by Frame of Essence. Next week we will look at everyone’s favorite, bitcoin and blockchain. Until then, good luck.