Uploaded December 2016 | Updated September 2026, 1 week ago
+++See my latest video: Internet Security or Die+++ youtu.be/CzB5n6_pBfk
Learn Public Key Cryptography in just 18 Minutes - Cryptography Tutorial
In this Cryptography Tutorial, I teach you Public Key cryptography basics. Specifically I’m going to explain to you how the cryptography works, that allows you to do online shopping. We are so used to online shopping, a.k.a. e-commerce, that we take it for granted. But e-commerce would not be possible at all without public key cryptography. Not only will I explained to you the details of public-key cryptography and how that makes e-commerce possible, but I’m going to explain it in 15 minutes, and explain it without math, by using the Blackbox model.
IMHO, cryptography basics should not include math. Cryptography explained with math simply muddies the waters to those without extensive math background.
Let’s start by taking a brief look at Classic cryptography, which is been around for thousands of years. Classic cryptography is also called secret key cryptography or Symmetric cryptography.
A cipher is some sort of a mathematical algorithm that we use to scramble text. In the blackbox model the cipher itself is the blackbox into which we input plaintext and the key. The plaintext is the message that we wish to encrypt and the key is simply a string of numbers, generally binary ones and zeros. The output we get from the blackbox is called ciphertext, which is the plaintext that has been encrypted in such a way that it can only be decrypted by someone that has the same key that originally encrypted the data in the first place.
Some examples of Symmetric cryptography that are used today are DES, Triple DES & AES. These are the same as the ciphers used for thousands of years in that the same key encrypts and decrypts them. However the modern algorithm is much stronger.
If we use of good cipher such as AES the only way an attacker can decrypt the ciphertext is to try every possible key, called a brute force attack. That is why the longer the key the more security you get.
Now supposing Bob wants to buy something on the website Alice.com. He needs to make sure his personal information cannot be seen by anybody eavesdropping on his conversation over the public Internet. At first glance it seems easy enough for Bob to encrypt his plaintext personal information with Symmetric cryptography, using a secret key, send it across the Internet in an encrypted fashion, and then have Alice.com decrypt the information with the same secret key. The problem arises: how do Bob and Alice.com both get the same secret key, while making sure no one else gets the key? The answer is no one has ever thought of a very efficient way. In order to do this, a whole new type of encryption called public key encryption, a.k.a. Asymmetric encryption had to be invented first. In fact it was invented in the 1970s thousands of years after mankind first started using cryptography.
+++See my latest video: Internet Security or Die+++ youtu.be/CzB5n6_pBfk
Learn Public Key Cryptography in just 18 Minutes - Cryptography Tutorial
In this Cryptography Tutorial, I teach you Public Key cryptography basics. Specifically I’m going to explain to you how the cryptography works, that allows you to do online shopping. We are so used to online shopping, a.k.a. e-commerce, that we take it for granted. But e-commerce would not be possible at all without public key cryptography. Not only will I explained to you the details of public-key cryptography and how that makes e-commerce possible, but I’m going to explain it in 15 minutes, and explain it without math, by using the Blackbox model.
IMHO, cryptography basics should not include math. Cryptography explained with math simply muddies the waters to those without extensive math background.
Let’s start by taking a brief look at Classic cryptography, which is been around for thousands of years. Classic cryptography is also called secret key cryptography or Symmetric cryptography.
A cipher is some sort of a mathematical algorithm that we use to scramble text. In the blackbox model the cipher itself is the blackbox into which we input plaintext and the key. The plaintext is the message that we wish to encrypt and the key is simply a string of numbers, generally binary ones and zeros. The output we get from the blackbox is called ciphertext, which is the plaintext that has been encrypted in such a way that it can only be decrypted by someone that has the same key that originally encrypted the data in the first place.
Some examples of Symmetric cryptography that are used today are DES, Triple DES & AES. These are the same as the ciphers used for thousands of years in that the same key encrypts and decrypts them. However the modern algorithm is much stronger.
If we use of good cipher such as AES the only way an attacker can decrypt the ciphertext is to try every possible key, called a brute force attack. That is why the longer the key the more security you get.
Now supposing Bob wants to buy something on the website Alice.com. He needs to make sure his personal information cannot be seen by anybody eavesdropping on his conversation over the public Internet. At first glance it seems easy enough for Bob to encrypt his plaintext personal information with Symmetric cryptography, using a secret key, send it across the Internet in an encrypted fashion, and then have Alice.com decrypt the information with the same secret key. The problem arises: how do Bob and Alice.com both get the same secret key, while making sure no one else gets the key? The answer is no one has ever thought of a very efficient way. In order to do this, a whole new type of encryption called public key encryption, a.k.a. Asymmetric encryption had to be invented first. In fact it was invented in the 1970s thousands of years after mankind first started using cryptography.
