Community Submission - Author: Caner Taçoğlu
Decryption is the act of reverting an encryption process so that previously encrypted information can be visualized or accessed. It involves the conversion of unreadable data (ciphertext) into readable (plaintext).
So while encryption is the process of making data unreadable, decryption is the process of converting the encrypted information back to its original and understandable form. Such a method of encrypting and decrypting information depends on a specific kind of cryptographic keys.
Those keys are generated by the cryptographic algorithms and are usually denoted as a string of numbers and letters. A piece of encrypted information can be easily converted back to its original form by using its corresponding decryption key. But without the correct key, decryption becomes much more difficult and can only be achieved by brute-force attacks. Robust encryption algorithms generate keys that are practically impossible to break.
Cryptographic keys are used in both symmetric and asymmetric encryption. Depending on the way keys are generated and used, the techniques can be divided into two major groups known as symmetric key cryptography and public key cryptography (PKC).
In symmetric key cryptography, the same key is used to encrypt and decrypt a piece of information. Until 1976, this was the only known kind of encryption technique. On the other hand, public key encryption (or asymmetric encryption) makes use of a pair of keys, which are mathematically related. Such a pair of keys consists of a public and a private key. Data is encrypted with the public key but can only be decrypted using the private key.