The Data Encryption Standard (DES) became a standard in 1977 when adopted by several US federal government agencies. Today, the encryption is used extensively in many financial, VPN, and online encryption systems.
The origins of DES are based on the work of Harst Feistal using the Lucifer algorithm. The core principle of the algorithm is to take an input block of plaintext and dividing it in half. Each half is then put through an XOR operation to alter the other half.
Each DES key is 64 bits in length with each eighth bit ignored, leaving an effective length of of 56 bits.
There are five separate modes of DES, including:
- Electronic Codebook Mode (ECB)
- Cipher Block Chaining Mode (CBC)
- Cipher Feedback Mode (CFB)
- Output Feedback Mode (OFB)
- Counter Mode (CTR)