Share
Explore BrainMass

Cryptography and Information Security Problem

Bob believes that he has come up with a nifty hash function. He assigns a numeric value VChar to each letter in the alphabet equal to the letter's position in the alphabet, i.e., VA = 1, VB = 2, ..., VZ = 26. For a message, he calculates the hash value H = (VChar 1 x VChar 2 x VChar 3 ...x VChar N) mod(26). Bob uses this function to send a one-word message, PANEL, to his banker Bill, along with his calculated hash value for the message. Alice is able to intercept the message, and generates an alternative message that has a hash value that collides with Bob's original hash value. Show a message that Alice may have spoofed, and demonstrate that its hash value collides with Bob's original hash.

Va = 1 H= (16 * 1 * 14 * 5 * 12) mod 26
Vb = 2 p a n e l
Vc = 3
Vd = 4
Ve = 5
Vf = 6
Vg = 7
Vh = 8
Vi = 9
Vj = 10
Vk = 11
Vl = 12
Vm = 13
Vn = 14
Vo = 15
Vp = 16
Vq = 17
Vr = 18
Vs = 19
Vt = 20
Vu = 21
Vv = 22
Vw = 23
Vx = 24
Vy = 25
Vz = 26

Attachments

Solution Preview

For the word "panel", its hash value is H = (16*1*14*5*12) mod 26 = 24.
Alice need to find an alternative message with the same hash value.
So I can ...

Solution Summary

This cryptography problem on hashing is explained and a java program to complete it attached.

$2.19