Data Encryption Techniques are particularly used for ______.

Concept: Encryption is a confidentiality mechanism. An algorithm transforms plaintext into ciphertext under a key, and only a party holding the matching key can run the inverse transform and recover the original message. Its security goal is therefore secrecy — the data stays unintelligible to anyone who obtains it without the key.

Application: A data communication system carries a message over links, switches and intermediate nodes that neither endpoint controls, so anyone able to tap the path can read whatever crosses it. Encrypting at the sender and decrypting at the receiver means only ciphertext travels on the wire: an eavesdropper who captures every bit still obtains nothing intelligible without the key. That is why data encryption techniques are applied characteristically to protect data in a data communication system.

Cross-check — what encryption does not do:

• Storage space. Ciphertext is normally the same size as its plaintext, or slightly larger once padding, an initialisation vector or a block-alignment remainder is added. Shrinking data is the job of compression, which exploits redundancy such as repeated strings and predictable patterns; encryption output is deliberately near-random and therefore almost incompressible.

• Data integrity. Detecting that data was altered is provided by hash functions, message authentication codes (MAC) and digital signatures, which attach a verifiable check value to the message. With an unauthenticated cipher an attacker can modify the ciphertext and the receiver decrypts it to altered plaintext with no alarm raised, so encryption on its own neither guarantees data integrity nor reduces it — integrity is simply a different security service.

Hence the characteristic use of data encryption techniques is protecting data in a data communication system: confidentiality of the message while it is in transit.