Decryption

Decryption is the process of converting coded, or “encrypted,” data back into its original form, so it can be understood only by its rightful recipients. Decrypt is a generic term for decipher and decode. The root prefix “crypto” comes from the Greek “kryptos,” meaning “hidden or secret.” Thus, decryption essentially means decoding a hidden secret.

Both terms, decode and decipher, refer to a system of encryption in which data are disguised with other data to make unreadable. However, the factor that differentiates the two is the level of substitution used during encryption. Decipher means to unscramble a message that uses substitution at the letter level, whereas decode refers to substitution at the word or phrase level.

The most popular encryption/decryption schemes are the symmetric and asymmetric encryption schemes. To easily recover the contents of an encrypted signal, the correct decryption key is required. The key is an algorithm that reverses the work of the encryption algorithm. Alternatively, a computer can be used in an attempt to "break" the cipher. The more complex the encryption algorithm, the more difficult it becomes to eavesdrop on communications without access to the key.