S-boxes in Blowfish

[Q-bel]

Hey there, Im just working on a project for a crypto class and I decided to implement blowfish on VHDL(Hardware Description Language) to run on a hardware piece. Anyways, the real question is that the blowfish algorithm initializes its famous 4 S-boxes and a P array with the hex values of the decimal part of pi. I have found some programs which calculate pi with enough accuracy to get enough values for initialization of these S-boxes (they are 4 each with 256 32 bit entries). Problem is I dont know how to change this number later to hex or even binary. Any help here would be greatly appreciated.
I know I haven't given much information on the algorithm but it is not really necessary to understand what I need.

[i2c]

hey sounds like a cool project, are you gonna have two cpld or fpga's? one encrypting and on decrypting?

I found this page,

http://www.ee.ualberta.ca/~elliott/ee552/studentAppNotes/1998f/blowfish_encryption/
http://personal.sip.fi/~lm/c2txt2c/blowfish.txt <---hehehe :)
http://www.packetstormsecurity.org/crypt/blowfish/

dunno whether there any help...

i2c

[sec_ware]

Hi

An excellent list of the initialisation numbers for the 18x32bit P and the 4 256x32bit S-boxes
can be obtained here[1], in a useful format.

How is this computed?

The starting point chosen by Bruce is the number: Pi - 3 = 0.14159265...

How can this number be assembled in hex-base? As follows:


First digit: 1/16 = 0.0625


Q: How often does that fit into this number 0.14159...?
A: 2 times.


0.14159265 - 2* 1/16 = 0.01659265...


Note: This number 0.01659265... is smaller than 1/16, and thus has to
be "approximated" using the next smaller possibility: 1/(16^2)


Second digit: 1/(16^2) = 0.00390625


Q: How often does that fit into the rest-term 0.01659265...
A: 4 times


0.14159265 - 2* 1/16 - 4*1/(16^2) = 0.0009676535...



Third digit: 1/(16^3) = 0.00024414...


Q: How often does that fit into the rest-term 0.000967653...
A: 3 times

and the fourth digit: 15 times. 15 in hexadezimal notation is F.

Thus: 24 3F ...
etcetc

The initialisation starts with P, then S0, S1, S2 and finally S3.


Cheers.

[1] http://www.sstorie.com/school/cs4821/blowfish/BlowfishSPInit.h

[Q-bel]

Thanks a lot guys, definitely going to help. Oh and i2c, ill be using fpga's .