Cryptography Resources

The word "cryptography" comes from the Latin words for "secret writing." It relates to the science of concealing the meaning of something. In a modern-day sense, the word cryptography often relates to information security — the means by which digital files or transmissions are secured so that they are only visible to authorized users.

The Origins of Modern Cryptography

Egyptians were known to use codes as early as 1900 BCE, although these were thought to be recreational, rather than designed for serious security purposes. The ancient Greeks and the Romans had methods of codes and ciphers, while the Arabs were the first to use cryptography in a way that we would recognize today, around 1,000 years ago.

Early attempts at cryptography were often inspired by war. Messages would be encoded as a way to communicate without interception by the enemy. In the modern world, millions upon millions of secure, encoded transmissions happen online each day -- and cryptographic standards are used to protect everything from banking data to health information, and even simple instant messaging.

Classical Encryption Techniques

Why Cryptography is Critical Now

Without cryptography, ecommerce as we know it would be impossible. Most of the other information exchanges online would be fraught with risk; the simple act of using social media could be a treacherous proposition. The methods we now use to encrypt even the simplest kind of information are incredibly sophisticated, in an attempt to outpace malicious users.

Developers have three potential ways to encrypt data: a secret key system, a public key system, or a hash function. All of these have their own pros and cons. Additionally, many of the methods we use today involve uncrackable ciphers — or systems that are equivalent to being uncrackable. For example, the AES256 algorithm is one of the most commonly used encryption algorithms on the planet; it would take billions of years for a supercomputer to crack the code.

Hackers are constantly looking for ways to bypass security, meaning no system should ever be considered impenetrable. Constant evolution is essential. In many cases, it's easier to simply trick a user into revealing their password or key, rather than trying to solve a cryptographic puzzle, or use brute force hacking to gain access to a system.

Finite Fields

A finite field (or Galois field) is a mathematical construct with a finite number of elements. This concept forms the basis of most encryption techniques.

Advanced Encryption Standard

The AES standard led to algorithms such as AES256. These have been widely adopted across the internet, mainly because many governments use them as their chosen standard for encryption.

Confidentiality Using Symmetric Encryption

Symmetric encryption uses the same key for both encryption and decryption. These are sometimes referred to as secret key algorithms.

Number Theory and Hash Algorithms

In the context of the internet, hashing is often used to obfuscate passwords and other pieces of data. There are many different hashing functions and methods, including MD5 and SHA-1.

Digital Signatures

Digital signatures are used to verify the identity of a sender or recipient. They are often used when transmitting financial details, or exchanging business contracts.

Authentication Applications

Authentication applications make cryptography easier. Kerberos is one example of a protocol that is used in a range of applications.

Electronic Mail Security

Email is inherently an insecure method of communication. The resources below detail various ways that email can be made more secure.

IP Security and Web Security

SSL stands for Secure Sockets Layer. It's fundamental in the provision of ecommerce stores, online banks, and digital services.


A firewall is a software application or hardware device that controls access to a computer or network.

Further Reading and Resources

We have more guides, tutorials, and infogragphics related to using the internet safely:

How to Create the Perfect Password

Confused about how to create a great passowrd? Check out our infographic, How to Create the Perfect Password.