Encryption
Encryption transforms plaintext into ciphertext using an algorithm and key so that authorized parties can recover the original information.
Hashing
A cryptographic hash produces a fixed-length output and is designed to make reversal and undetected modification difficult. Hashing is not encryption because there is no decryption key.
Digital certificates
A certificate contains identity information, a public key, validity information, and a digital signature from an issuing authority. It supports authentication and trusted key distribution.
Keep the purposes separate
Many errors begin when people treat encryption, hashing, encoding, signing, and certificates as interchangeable. Each solves a different problem and depends on sound key and trust management.
Certification relevance
This subject appears in or supports the following certification bodies of knowledge: