Crypto 101

By Leia Fee

“So how does that work then?” Jimmy asked brightly.

Langly rolled his eyes and gave him an, ‘I’m going to regret this,’ look.

“All right.  Suppose Bob and Alice want to send each other a secret message.”


“The problem is the line they’re using isn’t secure and Eve is able to intercept—”

“Oh Langly, that’s not fair,” Jimmy protested.  “You always assume the worst—”

“Not Yves, Jimmy.  Eve.  It’s just the example, okay?  It’s short for ‘eavesdropper’ or something.”


“Okay, so Alice—”

“What are Alice and Bob short for then?”


“Alice and Bob.  You said—”

“They’re just examples!  A and B, they could be anything.”

“But why…”

Frohike looked up as Langly gave a frustrated wail and chuckled.  “You planning on writing ‘Ciphers for Dummies’, Langly?”

Langly shot him a glare and turned back to Jimmy, stubbornly determined now to get his point across.

“The names don’t matter, Jimmy.  Two people want to send each other an encoded message…”


Following Langly’s less than successful technical explanation, Frohike had joined in with the short history of private cryptography.

“Well the government wasn’t too happy about the prospect of everyone having strong crypto on their private message, and the people up at Fort Meade and Langley were pushing for—Jimmy?”

Jimmy was wearing the confused, expectant expression that meant he was about to ask yet another question.


“Not me, Jimmy!”  Langly rolled his eyes, “With an ‘e’.  CIA headquarters?”

“Ah, got you.  And Fort Meade…”


“Right.  Got it.  I suppose they wanted codes to talk to the spaceships.”

This time it was Frohike who threw up his hands.

“NSA, Jimmy.  Not NASA!”


Langly and Frohike had glued themselves to two of the computers, as much to escape Jimmy’s questioning as to hopefully speed up the password cracking process.

“So what are they doing?”  Jimmy had parked himself next to Byers, who was the only one still offering any explanations.

“Running a program to try and find the password to decrypt the data we acquired.”


“Well at the moment, by working through a list of possible passwords.”

“Won’t that take a long time?  It could be anything right?”

“Right, but people aren’t always as careful as they should be.  Often they use easy to guess passwords, like their dog’s name or their birthday…”

“The computer could guess my dog’s name?  I mean, if I had a dog.”

“Probably, eventually.”


“Jimmy…”  Byers suspected Jimmy hadn’t quite grasped the concept but before he could clarify he was interrupted by an excited yelp from Langly.

“We got it!  We’re in!”

Byers hurried over with Jimmy close at his shoulder.  They peered over Langly’s shoulder at the data scrolling past.

“So, uh, what was the dog’s name?”

Three pairs of eyes turned to stare at him.


Back to Snippets.