Explain the difference between hashing, encryption and encoding.

What the interviewer wants to hear

• Encoding changes format for compatibility and is not security
• Encryption protects confidentiality and is reversible with a key
• Hashing is one-way and used for integrity and password storage
• Gives examples such as Base64, AES and SHA-256

Model answer

Encoding changes data into another format so systems can handle it, like Base64 or URL encoding. Anyone can decode it, so it gives no security, although attackers often use it to hide commands, such as encoded PowerShell. Encryption protects confidentiality. It is reversible, but only with the right key. Symmetric algorithms like AES use one shared key, while asymmetric ones like RSA use a public and private key pair. Hashing is a one-way function that produces a fixed-length digest, such as SHA-256. You cannot get the original data back, so it is used to check integrity and identify files, for example matching a malware hash. For passwords we use slow, salted hashing algorithms such as Argon2 or bcrypt rather than plain SHA-256.

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