Errong2
- 1. The Adventures of NeveErrongPart II: The London Eye
- 2. From the Desk ofTHE CHIEF Here’s the message:XNKAL IITOBCRBLO CKBLOCXBCA TIGBSAnd this came with it:Use the code where 4=19 and 9=22Agent Errong:We’re hot on the trail of those vicious vagrants, the agents of E.V.I.L.L. I just hope we are not too late to save the World Cup! You’ve made it to London and luckily vigilant Agent Al Waysright has discovered another clue. Get him to help you out with this one and figure out what to do next. Heaven knows what E.V.I.L.L. will do if we don’t stop them... Get to work!
- 3. Known-plaintext attackLet E(x) and E(y) be the ciphertext letters for plaintext letters x and y. In the affine cipher:E(x)=(a*x+b)%26E(y)=(a*y+b)%26Thus, E(x) – E(y) = ((a*x+b) – (a*y+b))%26 = (ax – ay + b – b)%26 = (a(x-y))%26((x-y)-1 * (E(x) – E(y)))%26 = aWhere ((x-y)-1 is the multiplicative inverse mod 26. Once we know a, we can easily find b:E(x) = (a*x + b)%26(E(x) – ax)%26 = b
- 4. Finding the KeyNow find b :E(x) = (ax+b)%26(E(x) – ax)%26 = b(19 – 11*4)%26 = b-25%26 = 1Thus the key is(11,1) and we can now construct our alphabet!Our clues were 4=19 and 9=22a = ((x-y)-1)*(E(x) – E(y))%26 Find the inverse of (9-4)%26 5*n%26=15*21=105105%26=1Now, a = 21*(22-19)%26a = 63%26 = 11a (11*0+1) = 1%26 = 1 Bb (11*1+1) = 12%26 = 12 Mc (11*2+1) = 23%26 = 23 Xd (11*3+1) = 34%26 = 8 IFind the rest on your own!
- 5. PT CT-----a Bb M c Xd Ie Tf Eg Ph Ai Lj Wk Hl Sm Dn Oo Zp Kq Vr Gs Rt Cu Nv Yw Jx Uy Fz QCracking the CodeHere was our message:XNKAL IITOBCRBLO CKBLOCXBCA TIGBSNow to convert it back to plaintext:XN = cuCan you solve the code and read the message??
- 6. From the desk of THE CHIEFAgent Errong,Nice work, gumshoe. Now we can continue to dog those dastardly degenerates, the agents of E.V.I.L.L.! Go with courageous Agent Al Waysright to St. Paul’s Cathedral in the heart of London and see what new clues you can pick up! I’ll be here at headquarters, throwing darts and anxiously awaiting your news!-THE CHIEF