What Is Decryption?

Date First Published: 19th May 2023

Topic: Cybersecurity

Subtopic: Security Mechanisms & Technologies

Article Type: Computer Terms & Definitions

Difficulty Level: 4/10

Learn more about what decryption is in this article.

Decryption is the process of converting encrypted information back into its original plaintext form. It is the opposite of encryption, which refers to the process of scrambling sent information into random characters and symbols so that it is unreadable by anyone if intercepted. Decryption allows the intended party to turn the encrypted information into the original information so that it is readable to them, but not readable to anyone intercepting it during the transmission process.

How Does Decryption Work?

Decryption works by using the opposite encryption algorithm used to scramble the data. Decryption works in two different ways, depending on the type of encryption. In symmetric encryption, when a single key is used to encrypt and decrypt a message and all parties must use the same key, only someone with the appropriate key can decrypt (unlock) it to get it back to the original state. Stored data, including documents usually use symmetric encryption.

In asymmetric encryption, which includes two keys, called the public and private keys. 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.

Data sent during transmission is usually encrypted using asymmetric encryption. This is because a single encryption key is a security risk as it could be intercepted during transmission. With only one single key, the message could be decrypted by unauthorised users.

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