Decrypt

Decrypt is the process of converting encrypted data (ciphertext) back into its original plaintext form. It is the inverse operation of encryption, which transforms plaintext into ciphertext to provide confidentiality. Decryption requires the appropriate decryption algorithm and, in most cases, a key. Without the correct key, the decryption output should be indistinguishable from random data.

In symmetric cryptography, the same key is used to encrypt and decrypt; thus, whoever has the key can decrypt. In asymmetric cryptography, a public key is used to encrypt and a private key to decrypt; decryption is performed with the private key, which must be kept secret. The decryption process reverses the encryption steps, and for block ciphers it also reverses padding and mode-specific operations.

If ciphertext is altered or the wrong key is used, decryption may fail or produce garbled output. Proper key management and integrity checks are essential to ensure that decryption yields the correct plaintext and that the data has not been tampered with.

Common algorithms include AES and DES for symmetric decryption, and RSA or ECC-based schemes for asymmetric decryption. Decryption is a fundamental operation in cryptography, enabling authorized parties to recover original data while preserving confidentiality during storage and transmission.