You are viewing a free preview of this lesson.
Subscribe to unlock all 10 lessons in this course and every other course on LearningBro.
Symmetric encryption uses a single shared key for both encryption and decryption. It is the workhorse of modern cryptography — fast, efficient, and used to protect the vast majority of data at rest and in transit.
Sender: Plaintext ──▶ [ AES Encrypt + Key ] ──▶ Ciphertext
Receiver: Ciphertext ──▶ [ AES Decrypt + Key ] ──▶ Plaintext
Both parties must possess the same secret key. The fundamental challenge is: how do you securely share the key?
| Feature | Block Cipher | Stream Cipher |
|---|---|---|
| Processing | Encrypts fixed-size blocks (e.g., 128 bits) | Encrypts one bit or byte at a time |
| Speed | Slightly slower per byte | Very fast, especially in hardware |
| Use case | File encryption, disk encryption, TLS | Real-time communications, wireless |
| Examples | AES, DES, 3DES, Blowfish | ChaCha20, RC4 (deprecated) |
DES was adopted as a US federal standard in 1977:
Subscribe to continue reading
Get full access to this lesson and all 10 lessons in this course.