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What Is Encryption?

What Is Encryption

Date First Published: 22nd June 2022

Topic: Cybersecurity

Subtopic: Security Mechanisms & Technologies

Computer Terms & Definitions

Difficulty: Medium

Difficulty Level: 4/10

Learn more about what encryption is in this article.

Encryption is the use of complex algorithms to encode sent information into random characters and symbols so that it cannot be read by any unauthorised users if intercepted. For example, HTTPS, the secure version of the Hypertext Transfer Protocol used for communicating over the World Wide Web uses SSL/TLS to encrypt data, convert plaintext to ciphertext, and then decrypts the message when the recipient receives it. Encryption has also been implemented in other protocols, such as SMTP and FTP as sensitive information is often transmitted over those protocols.

Encryption is also used to secure data sent over Wi-Fi networks. For example, most wireless networks use WPA, or WEP when WPA is unavailable, to encrypt communications between the device and the wireless router. Longer encryption keys make it harder for the encryption key to be brute-forced.

Note: Info Icon

Data is encrypted using encryption algorithms. An example of a simple encryption algorithm that would not be used as someone could easily work out the algorithm would be 'Mary' (plaintext) - 'Qevc' (ciphertext). The encryption algorithm here is shifting the letters of the alphabet by three characters.

What Is The Encryption Process?

The encryption process takes place in four steps:

  • The user sends a message to a server through a protocol.
  • Checks are performed to verify that the certificate is valid and signed by a trusted provider.
  • The message is encrypted into ciphertext using the public key of the server.
  • The server decrypts the session key using its private key and the recipient receives the deciphered data.

Types Of Encryption

Symmetric encryption

Also known as private key encryption, symmetric encryption is when a single key is used to encrypt and decrypt a message and all parties use the same key. It must be given to the recipient of the message for decryption. Similar to a physical key, it locks (encrypts) data so that only someone with the appropriate key can unlock (decrypt) it.

Stored data, especially confidential documents, sometimes needs to be encrypted to prevent unauthorised access as if they gained access to a computer system, they would not be able to read any contents of the file. Stored data is usually encrypted using symmetric encryption. However, the disadvantage of symmetric encryption is that if the encryption key is lost, it would be impossible to decrypt the data, making it unusable. Some well-known symmetric encryption algorithms are AES, 3-DES, and SNOW.

Asymmetric encryption

Also known as public-key encryption, this is a much more secure method of encryption. Asymmetric encryption consists of two keys, called the public and private keys. The public key is available to anyone that wants to encrypt a message to a recipient. Data sent during transmission is usually encrypted using asymmetric encryption. This is because sharing the encryption key is a security risk as it could be intercepted during transmission and with one single key, the message could be decrypted by unauthorised users. However, asymmetric encryption can have an impact on processing power when working with large amounts of data due to its complex mathematical formulas. It uses more processing power than symmetric encryption.

The private key is only available to the recipient and is used to decrypt the message. The decryption key is kept private, as suggested in the term 'private key'. This process usually takes place automatically and the recipient does not need to know the decryption key as the software stores it.

Some well-known asymmetric encryption algorithms include RSA and elliptic curve cryptography. SSL/TLS uses both symmetric and asymmetric encryption to encode data into an unreadable form in order to prevent unauthorised access.

Importance Of Encryption

Encryption is important for various reasons, including:

  • Security - Encryption ensures that no sensitive information can be read by anyone other than the intended recipient if it was intercepted. It allows users to exchange sensitive information without leaking the data to other users.
  • Data integrity - Encryption helps prevent cyberattacks, such as on-path attacks. Encryption ensures that data sent over the internet cannot be interfered with on the way.
  • Authentication - Encryption helps to verify that the owner of a website owns the private key listed in the SSL/TLS certificate, ensuring that visitors are connected to the real website.
  • Regulations - Some government regulations, such as GDPR and HIPAA require businesses that handle user data to keep it encrypted.

What Are Brute-Force Attacks In Encryption?

In encryption, a brute-force attack occurs when an attacker attempts to guess the encryption key by making millions or even billions of guesses until they guess the correct encryption key. Longer encryption keys reduce the chance of brute-force attacks. For example, a 128-bit AES key would take around six months to crack. An AES-256 key would take billions of years to crack.


Thomas Jefferson proposed a cipher to encode and decode messages to provide a more secure method of military correspondence around 1790. The cipher, known as the Wheel Cipher or the Jefferson Disk was proposed as a spool that could scramble an English message of up to 36 characters even though it was never built. The message could then be decrypted by plugging in the scrambled message to a receiver with an identical cipher.

In 1917, a similar device to the Jefferson Disk, called the M-94 was developed by US Army Major Joseph Mauborgne. This device was used in US military communications until 1942.

As of now, encryption is used for security purposes when transmitting data. Encryption is constantly evolving to prevent eavesdropping attacks as computing power continues to increase. With one of the first modern cipher suits, DES, used a 56-bit key with 72,057,594,037,927,936 possibilities of being able to be cracked in 22 hours and 15 minutes by EFF’s DES cracker in 1999, which used a brute-force method of cracking.

Modern encryption standards usually use stronger key sizes of 256-bit keys. TwoFish, ChaCha20-Poly1305, and Serpent are configurable up to 512-bit. Cipher suits that use 128-bit or higher encryption keys cannot be brute-forced due to the extremely high total number of possibilities. The most common option for cracking ciphers with a high key size is vulnerabilities in the cipher, such as backdoors. For example, RC4 was cracked due to vulnerabilities in the cipher.


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