What Is Encryption?
Encryption is the process of transforming readable data (plaintext) into an unreadable scrambled format (ciphertext) using a mathematical algorithm and a key. Only someone with the correct decryption key can reverse the process and read the original data. Encryption is the foundation of secure communication, data storage, and authentication across the internet - It underpins HTTPS/TLS, VPNs, and end-to-end messaging.
Symmetric vs Asymmetric Encryption
| Property | Symmetric | Asymmetric |
|---|---|---|
| Keys used | One shared key for both encrypt and decrypt | Key pair: public key encrypts, private key decrypts |
| Speed | Very fast - Suitable for bulk data | Slow - Typically 100-1000x slower |
| Key distribution problem | Yes - How do you securely share the key? | No - Public key can be shared openly |
| Common algorithms | AES-256, ChaCha20, 3DES | RSA-2048/4096, ECC (P-256, X25519), ElGamal |
| Typical use | Encrypting files, VPN data tunnels, disk encryption | TLS handshake, email signing, SSH authentication |
Common Encryption Algorithms and Their Strength
| Algorithm | Key Size | Status | Use Case |
|---|---|---|---|
| AES-256 | 256 bits | Secure - Recommended | File encryption, VPNs, TLS data |
| AES-128 | 128 bits | Secure - Widely used | TLS, disk encryption (FileVault, BitLocker) |
| ChaCha20-Poly1305 | 256 bits | Secure - Recommended for mobile | TLS 1.3, WireGuard VPN |
| RSA-2048 | 2048 bits | Acceptable (4096 preferred) | TLS certificates, SSH, PGP |
| RSA-1024 | 1024 bits | Insecure - Deprecated | Legacy only; do not use |
| DES / 3DES | 56 / 112 bits | Insecure - Deprecated | Legacy systems only |
| MD5 / SHA-1 | Hash functions | Broken for signatures | Do not use for integrity or signatures |
Encryption at Rest vs In Transit
- Encryption in transit protects data as it travels over the network - HTTPS/TLS is the standard for web traffic. Verify any site's certificate with our SSL checker.
- Encryption at rest protects data stored on disk - BitLocker (Windows), FileVault (macOS), and LUKS (Linux) are common tools.
- End-to-end encryption (E2EE) means only the communicating parties can decrypt the data - Not even the service provider. Signal, ProtonMail, and WhatsApp (with caveats) offer E2EE.
- Encrypting data in transit but not at rest is a common gap - If a server is breached, unencrypted stored data is exposed. Combine with a firewall and VPN for layered protection.