Penyulitan mengubah data menjadi bentuk yang tidak boleh dibaca (ciphertext) yang hanya boleh dinyahsulit dengan kunci yang betul — melindungi kerahsiaan. Memahami penyulitan simetri berbanding asimetri, dan data semasa transit berbanding sedia tersimpan, adalah penting untuk melindungi data sensitif.
Penyulitan simetri berbanding asimetri
SYMMETRIC → ONE shared key encrypts AND decrypts (e.g. AES):
✓ fast, efficient → for bulk data (encrypting files, databases)
✗ both parties need the same key (key distribution is the challenge)
ASYMMETRIC → a KEY PAIR: PUBLIC key (encrypt / verify) + PRIVATE key (decrypt / sign):
→ encrypt with the public key, only the private key decrypts (e.g. RSA, ECC)
✓ solves key distribution (share the public key freely); enables signatures
✗ slower → used for key exchange, signatures, not bulk data
→ Often COMBINED: asymmetric to exchange a symmetric key, then symmetric for the data
(e.g. how TLS works).
