Symmetric Key Encryption
Data Encryption Standard (DES)
- Extremely popular symmetric key algorithm
- DES breaks the plaintext into blocks of 64 bits
- It then encrypts each block of plaintext using a 64-bit key
- However, it is proper to say that DES uses a 56-bit key, because 8 of the key bits are redundant (can be computed from the other 56)
- 56-bit key is small, giving inadequate strength for important transactions (OK for small ones)