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Encryption Fundamentals
Symmetric vs. asymmetric encryption, hashing, and how TLS combines them.
What it is
Encryption protects data confidentiality. The two core families — symmetric and asymmetric — solve different problems and are usually combined, not chosen between.
Key points
- Symmetric encryption (AES): one shared key encrypts and decrypts — fast, but requires securely distributing the key first.
- Asymmetric encryption (RSA, ECC): a public key encrypts, only the matching private key decrypts — solves key distribution, but much slower than symmetric.
- TLS combines both: an asymmetric handshake negotiates a shared symmetric key, then symmetric encryption handles the actual (much larger) data transfer — this is why HTTPS is both secure and fast.
- Hashing is not encryption — it's one-way. Used for password storage (with salting, via bcrypt/Argon2, never raw SHA-256) and integrity verification, not for anything that needs to be decrypted later.