# Construct rainbow table to break DES for a fixed plaintext

I'm facing a project where I need to build a rainbow table to break DES for a fixed plaintext. I've already collected information about Hellman, DP, rainbow table method. Finally, I chose the rainbow table approach. I've read about the topic “Rainbow table for DES with all-zero plaintext”. Now, my consideration how to choose good parameter to obtain highest success rate.

The notations:

• N: search space
• m: number of chains
• t: chain length
• l: number of tables

Stopping matrix is $C = mt/N$. Success rate is $R = 1 - e^{-C\cdot l}$. By Theorem 6, $C = (-\ln(1- R))/l < 2$.

So… I can calculate $l$ to obtain expected $R$, from $l$ I can derive $C$. Now I´m wondering: can I simply choose $m$ and $t$ such that $mt/N = C$, or must it be dependent on something else?

• Cracking DES in what usage? You can't use a rainbow table to crack DES in general; you can only use it to crack DES with fixed plaintext. Mar 20 '15 at 5:23
• yes, i know it and i have a fixed plaintext. Mar 20 '15 at 5:35