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What is cryptography?

From ancient Roman ciphers to modern computer-generated encryption keys with trillions of combinations, cryptography has been a fundamental part of human life for millenia. Now, as technology marches on, cryptography methods are becoming ever more sophisticated.

Charles Whitmore

Charles Whitmore

May 20, 2021 · 4 min read

What is cryptography?

Encrypted emails and hashed passwords have long been a part of everyday life for those who prioritize their online security. But how exactly does modern cryptography work? And what are the advantages and disadvantages of relying on these security techniques?

How does Cryptography work?

Cryptography refers to the creation of a secure means of communication through use of an algorithm and a decryption key. In most cases, that involves scrambling text until it is unreadable, while still being able to reverse that process if you or someone you trust needs to see it. The vital aspects of cryptography are the complexity of the algorithm used in the scrambling process, and the key needed to decode the message. The more complex the algorithm, the stronger the encryption.

The algorithms used thousands of years ago would been involved rearranging or shifting letters within the original alphabet. But modern algorithms aren’t limited by a 26-character alphabet, so the strength and complexity of today’s digital cryptography can be practically unbreakable.

Before a written message is encrypted, it’s referred to as plaintext. After encryption, the remaining gibberish is called ciphertext.

Types of Cryptography

There are three main types of cryptographic algorithms, each with a specific purpose.

  • Secret Key. This is often referred to as symmetric encryption, because it’s the same key to encrypt and decrypt the data. This form involves one or more parties having access to the same decryption key. The key can only be shared by the original holder.
  • Public Key. Also known as asymmetric encryption, due to the need for two different keys. One user has a key that encrypts the message, while another has the decryption key alternative. Once the first key has been used to turn the plaintext into ciphertext, the same key can’t be used to decrypt it. The sender will always have access to the public key, and the receiver will have the tools to decrypt the message.
  • Hash functions. This is a one-way encryption tool. What’s the point of an algorithm that encrypts and doesn’t decrypt? It serves as an authenticator, of sorts. It’s used to make sure a file hasn’t been changed or altered. A hashing algorithm will convert data into a fixed-length string of text called a hash value. The hash value of that data is then checked against the stored hash value in whatever service the user wants to access. If the hash values match, then access is granted. Each file will have a unique hash value, almost like a barcode.

Examples of Cryptography

Secret Key cryptography is often used when bulk encryption is needed. Encrypting entire databases would normally be the work of symmetric encryption. Asymmetric encryption, though more secure, is a far slower and power intensive method. Most banking systems will use symmetric encryption, too.

Symmetric encryption protocols: AES, Triple DES, Blowfish.

Public key encryption, or asymmetric encryption, is often found in blockchains for cryptocurrencies. This highly robust form of protection is stronger than symmetric encryption and used to authorize crypto transactions. The nature of the encryption process also makes it perfect for digital signatures.

Asymmetric encryption protocols: RSA, Diffie-Hellman key exchange.

Hashing is a cryptographic tool meant for checking the authenticity of a file or message, due to the unique nature of the hash value. Technically, it is possible for 2 files to have the same hash value but it took Google devoting two years of resources to make the concept a reality. It’s possible, but incredibly improbable it would ever happen.

Hashing encryption protocols: SHA-1, SHA-2, Tiger.

Advantages and disadvantages of cryptography

Secret Key/Symmetric encryption

Symmetric encryption only requires the use of one key, so the encryption and decryption process is a lot quicker than it would be for asymmetric cryptography.

However, the disadvantage of symmetric encryption lies in the singular key. There is one copy of each key, at either end of the process. The act of keeping the key safe and secure from prying eyes is a risk in itself, especially if you’re constantly updating and changing the secret key needed. The exchanging of the key between two parties is often where most errors occur.

Public key/Asymmetric encryption

Asymmetric encryption is often regarded as the safer form of cryptography techniques, due to the need for two different keys. There is no need to transfer keys, either. The public key is always available to anyone looking for it, and only the recipient has access to the private decryption key.

The disadvantage of asymmetric encryption is that it’s slow. Every form of symmetric encryption will be faster. It takes a lot of power and time to secure files and messages asymmetrically.


Hashing has a limited number of uses, but can be very effective in certain circumstances. Providing a file with a barcode-like identifier can be a foolproof technique for authenticating a message.

Cryptography and VPNs

Cryptography and network security go hand in hand. NordVPN employs symmetric and asymmetric encryption protocols to ensure your safety online. AES-256, a symmetric protocol, has more combinations than there are atoms in the universe.

NordLynx, NordVPN’s fastest VPN protocol, uses an asymmetric encryption called ECC. ECC can create smaller and more efficient encryption keys, and has gained the praise and recognition of cybersecurity experts everywhere.

A VPN is the perfect tool to provide peace of mind while browsing online. One account with NordVPN will cover up to six devices: that’s an entire household protected with next-level encryption. NordVPN is dedicated to giving you the fastest, safest experience possible.

Online security starts with a click.

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