Implementing Blowfish using PIC16F877 « The Hardware Side of Cryptography

25 January 2008

Implementing Blowfish using PIC16F877

Filed under: encryption — Tags: Blowfish, encryption, Microcontroller, PIC16F877 — edipermadi @ 8:30 am

Again for crypto nutters , i’ve implemented blowfish encryption using PIC16F877. Blowfish was pretty simple to implement, it employs 32 bit addtion, bitwise XOR and substitution only. But wait, it uses 4096 bytes to implement SBOX Table Lookup, so you have to choose microcontroller with memory capacity greater than 4 kbytes.

Blowfish is one of symetric block cipher. It employs feistel structure with 32 bit wide on each side. It is royalty free and require no license. It’s faster than DES and IDEA. Yeah, its good for everyone. Its Free!

This implementation contains both of encryption and decryption routine. You can download and redistribute the code, but take your own risk and don’t forget to mention the source . So, If you are looking for an example of Blowfish implementation on hardware, you got the right page.

As a benchmark, the program takes 1216 cycles (1.2 ms) to do key setup. To encrypt one block of plain text, it takes 5100 cycles (5.1 ms) also, to decrypt one block of cipher text also takes 5100 cycles (5.1 ms). By this implementation, you can encrypt and decrypt 1.568 kbyte/s. I knew i was fairly slow, i keep trying to modify the code till the most effective one. Hopefully, someday i”ll have a chance to implement this on FPGA or CPLD.

Bruce Scheneier is the author of Blowfish Encryption/Decryption Algorithm. He own the algorithm. Big thanks to him. Check out his website here.