From charlesreid1

Caffeine Cipher

Story

The White Rabbit said he would call promptly at 8 AM. You check your watch. It's now 10:30 AM. It's very uncharacteristic of the White Rabbit to be late about anything, so you're worried something funny is going on. The White Rabbit has never been late before.

Finally, you call the White Rabbit. A very groggy White Rabbit appears on the video screen at the other end. "Mmmmmheeelloo?"

"Sorry to wake you, Mr. Rabbit, but I was expecting your call at 8."

"What time is it now?"

"It's 10:30, Mr. Rabbit."

The White Rabbit jumped out of bed, suddenly starting awake. "Oh no! I'm late! I'm late I'm late I'm late! I know what happened!"

The White Rabbit explained, as he hurriedly got dressed into his rabbit clothes and rushed downstairs and out the door to go to work, that POOKIE the evil supercomputer had been implementing its latest plan, which was to interfere with all of the coffee supplies in Wonderland. "Nobody in Wonderland can wake up on time!" exclaimed the White Rabbit. "It's awful! We must take back control of the coffee supplies, but we can't do that unless we solve POOKIE's latest puzzle."

"Have you tried drinking tea instead, Mr. Rabbit?" you ask.

"Well, hmm, I'd never thought of that one. I suppose that might work, yes. But only in the short term! Wonderland needs coffee! We must get our coffee back!"

"I am at your service."

"Wonderful!" the White Rabbit said, sounding very relieved. "POOKIE has sent us another puzzle. This one is different - POOKIE said its an Affine cipher. I sure hope you know what that means, because it's all Greek to me. Actually, POOKIE said Affine is Latin for "connected with". It's a special kind of code, I guess. In any case, we'll send it along. Good luck, Agent!"

"I'll look into it," you say. "And in the meantime, try some tea - I hear good things about Earl Grey."

"Very good, Agent!"

The call clicks off. Affine cipher? You aren't sure what that is, but you weren't about to tell the White Rabbit - what if he decided not to send the puzzle and the extra credit? You need the extra credit too bad. That's okay, you can wing it.

You open Google...

Ciphertext

Cryptotoken 1:

PUMJTZCNTYZMAPVCLIPHELMVLEAZMEAPCLCZPCQJEVZKIKPMRZUMJTZCNTYZMVPMZPCJTULMEPCEZKZTZCELITLQZMCHMXUELRMPUAX

Cryptotoken 2:

ETQGLBSQGLEMIAWOPWTLOTPSFILGTPLBETYIAWOHOILYSLOISPLWLBSQHWBTRWTTSOQGTT

Cryptotoken 3:

DDHVLJJZHDZPRLLZHDRPLLDDTTPDHVLJJDDBDTJPVJDHVLJJPRDRPLLDDTTPTJPVJZHJNDJZJRZFDLXDRPLLDDTTPTJPVJHDRLPJJRPFHHDBJJBZHLHRDDBBPZPZRNLHJRJTJJZFJNPRRPLLDDTTP

Solution

Procedure: Affine cipher ax+b, gcd modular arithmetic. This is equivalent to an unordered substitution cipher.

Token 1 (key = 9,15):

A prime number has no factors other than one and itself. Large prime numbers are an important element of modern cryptography.

Token 2 (key = 3,6):

In mathematics you don't understand things. You just get used to them. John Von Neumann

Token 3 (key = 8,3):

A number that is both a Fibonacci number and a prime number is a Fibonacci prime. The largest known Fibonacci prime has over six hundred thousand digits. Your secret key is Fibonacci.

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