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Caffeinated Bitstream

Bits, bytes, and words.

Implementing DES

DES, the Data Encryption Standard, was developed by IBM and the US government in the 1970's. Today, DES is considered to be weak and crackable, and a poor choice for anyone in the market for an encryption algorithm. However, many legacy protocols still use DES, so it's important to have implementations handy.

I recently found myself looking for a simple standalone DES implementation to study. Most of the open-source DES implementations are either highly optimized into obfuscation, or sloppily written. Either way, it's hard to find a clearly written and well-commented implementation suitable for educational purposes. I decided it would be a good exercise to write one myself. I wrote the implementation in Java, for the extra challenge of performing bit manipulations on signed primitive types. This implementation is undoubtedly very inefficient, but is well-commented and should be easy to understand for anyone who wants to dive into a sea of Feistel functions, S-boxes, variable rotations, and permutations.

References

I found the following resources useful in my study of DES:

Downloads

  • DES.java - My DES implementation in Java