Today is Alice’s birthday. She turned 24. Alice is twice as old as Bob was when Alice was as old as Bob now. How old is bob now ?

See the result on http://trickofmind.com/2009/06/alice-and-bob.html

It’s not only a wonderful story about the private lives of Alice and bob, but also goes on other fascinating topics as one of the best versions of the phonetic alphabet now existing.

A for ‘Orses
B for Mutton
C for Yourself
D for Mation
E for Brick
F for Vescence
G for Police
H for Consent

….

If you can’t find the coding theory behind it, you may find the answer in the The definitive Cockney Alphabet  

And if you want to read the complete John Gordon’s After Dinner Speech go to the great “The downlode Etext Library“, here’s an excerpt

…

So you see Alice has a whole bunch of problems to face. Oh yes, and there is one more thing I forgot so say - Alice doesn’t trust Bob. We don’t know why she doesn’t trust him, but at some time in the past there has been an incident.

Now most people in Alice’s position would give up. Not Alice. She has courage which can only be described as awesome. Against all odds, over a noisy telephone line, tapped by the tax authorities and the secret police, Alice will happily attempt, with someone she doesn’t trust, whom she cannot hear clearly, and who is probably someone else, to fiddle her tax returns and to organize a coup d’etat, while at the same time minimizing the cost of the phone call.

A coding theorist is someone who doesn’t think Alice is crazy.

—

World of Goo: Alice and Bob and the Third Party

And some alternate endings seen on reedit

Alternate ending 1.

After dating for a few weeks, Bob decides that they’re just not right for each other. He tries to let her down easy, but they have an incredibly ugly breakup. Alice pleads with Bob to take her back. He’s the best thing that ever happened to her.

After years of therapy, Alice is finally convinced that she’s over Bob. One morning she reads of a new cryptographic attack on Bruce Schneier’s blog. She applies it to the messages in the folder “CIPHERTEXT I HAVE YET TO CRACK”. She’s forgotten about Bob’s old message, but it’s in there, of course.

Poor Alice.

Alternate ending 2.

Alice applies a Shor’s algorithm attack using her quantum computer. The knowledge that Bob leaves the decision of who he will marry up to a cryptography test clues her in to Bob’s latent psychotic tendencies and saves her life by allowing her to sever all contact with him.

Seen on Peteris Krumins’ blog : http://www.catonmat.net/blog/musical-geek-friday-alice-and-bob/

Alice and Bob song and lyrics.

Alice is sending her message to Bob
Protecting that transmission is Crypto’s job
Without the help of our good friend Trent,
It’s hard to get that secret message sent
Work tries to deposit the check of your salary
But with no crypto, it’ll be changed by Mallory
You think no one will see what it is, you believe?
But you should never forget, there’s always an Eve…

[Chorus]
‘Cause I’m encrypting s**t like every single day
Sending data across the network in a safe way
Protecting messages to make my pay
If you hack me, you’re guilty under DMCA

DES is wrong if you listen to NIST
Double DES ain’t no better man, that got dissed
Twofish for AES, that was Schneier’s wish
Like a shot from the key, Rijndael made the swish
But Blowfish is still the fastest in the land
And Bruce used his fame to make a few grand
Use ECB, and I’ll crack your ciphertext
Try CFB mode to keep everyone perplexed

[Chorus]
‘Cause I’m encrypting s**t like every single day
Sending data across the network in a safe way
Protecting messages to make my pay
If you hack me, you’re guilty under DMCA

Random numbers ain’t easy to produce…
Do it wrong, and your key I’ll deduce
RSA, only public cipher in the game
Creating it helped give Rivest his fame
If we could factor large composites in poly time,
We’d have enough money to not have to rhyme
Digesting messages with a hashing function
Using SHA1 or else it won’t cause disfunction

[Chorus]
‘Cause I’m encrypting s**t like every single day
Sending data across the network in a safe way
Protecting messages to make my pay
If you hack me, you’re guilty under DMCA

Password confirmed. Stand by…

Alice and Bob were deeply in love. They were first-year students at university and they fell i love in the front row of the algebra lectures. It wasn’t love at first sight—it began as a competition to see who could answer the professor’s questions quickest. You see, the professor had a habit of asking the students how they thought the algebra would go, before telling then how she thought it should go. Most of the students thought these were rhetorical questions, but not Alice and Bob. More often than not, one or other of them answered the question. And more often than not, they were right. After a while, they found that they were no longer trying to impress the professor: they were trying to impress each other….

Download full PDF on: http://www.maths.qmul.ac.uk/~raw/pubs_files/AliceandBob.pdf

• Carol, Carlos or Charlie, as a third participant in communications.
• Dave, a fourth participant, and so on alphabetically.
• Eve, an eavesdropper, is usually a passive attacker. While she can listen in on messages between Alice and Bob, she cannot modify them. In quantum cryptography, Eve may also represent the environment.
• Isaac, an Internet Service Provider (ISP).
• Ivan, an issuer (as in financial cryptography).
• Justin, from the justice system.
• Mallory, a malicious attacker; unlike Eve, Mallory can modify messages, substitute her own messages, replay old messages, and so on. The problem of securing a system against Mallory is much greater than against Eve. The names Marvin and Mallet can also be used for this role.
• Matilda, a merchant (as in e-commerce or financial cryptography).
• Oscar, an opponent, is usually taken as equivalent to Mallory.
• Pat or Peggy, a prover, and Victor, a verifier, often must interact in some way to show that the intended transaction has actually taken place. They are often found inzero-knowledge proofs. Another name pair sometimes used is Pat and Vanna (after the host and hostess on the Wheel of Fortune television show).
• Plod, a law enforcement officer (also “Officer Plod”) from the children’s fictional character Mr. Plod, in the Noddy books by Enid Blyton.
• Steve, sometimes used in reference to Steganography.
• Trent, a trusted arbitrator, is some kind of neutral third party, whose exact role varies with the protocol under discussion.
• Trudy, an intruder: another alternative to Mallory.
• Walter, a warden, may be needed to guard Alice and Bob in some respect, depending on the protocol being discussed.
• Zoe, often the last party to be involved in a cryptographic protocol.