What Is Encryption

Encryption converts readable data into an unreadable form that only someone with the right key can reverse. Symmetric encryption uses one shared key, asymmetric uses a public and private key pair, and hashing is a separate one way process for integrity, not secrecy. Confusing hashing with encryption is the most common beginner mistake.

What encryption does

It protects confidentiality. Encrypted data in transit or at rest is unreadable to anyone without the key, so intercepting it or stealing the disk yields nothing usable.

Symmetric vs asymmetric

In practice they work together: asymmetric encryption securely exchanges a symmetric key, then the fast symmetric cipher encrypts the actual data. That is roughly how HTTPS works.

Hashing is not encryption

The critical distinction. Encryption is reversible with a key. Hashing is one way: you cannot get the original back. Hashing verifies integrity and stores passwords.

How passwords should be stored

Never encrypted, never plaintext. Hashed with a slow, salted algorithm like bcrypt or Argon2. When someone logs in you hash their input and compare hashes. A breach then leaks hashes, not passwords. This is why password cracking, covered in Kerberoasting, works on stolen hashes offline.

Where TLS fits

TLS is what puts the S in HTTPS. It uses asymmetric encryption to agree a key, then symmetric encryption for the session. Traffic sent without it is readable by anyone in the path, which you can see yourself with Wireshark.

Common mistakes that break encryption

• Confusing hashing and encryption
• Encrypting passwords instead of hashing them
• Fast hashes like MD5 or SHA-1 for passwords, with no salt
• Hardcoded or reused keys
• Rolling your own crypto instead of using vetted libraries

Learn how crypto breaks in practice

Understanding where encryption fails is core to security testing. Covered across the VAPT syllabus.