Introducing a new secure e-mail service

[GreyGeek]

Well, it's a few more steps than that. When Alice wants to send a private message to Bob, she encrypts the message with Bob's public key. When Bob receives it, he decrypts it with his private key. Presumably, only Bob has access to that private key, and thus confidentiality is assured.

If Alice wants to sign her message, the mail program creates a hash of the message content and encrypts that with Alice's private key to create the signature. Then the mail program sends the message and the signature to Bob. When Bob receives these, his mail program uses Alice's public key to decrypt the hash. Then his mail program computes its own copy of the message hash. If this copy of the hash matches the decrypted hash, then we know that the message wasn't tampered with and that it actually came from Alice.

Yup. You posted that last year sometime. I do it right. I just can't explain it right.
"My mind is going, Dave, I can feel it ..."

[SteveRiley]

Who the f@*% is Alice? And why is she sending encrypted email to Bob? What has she got to hide?

The Story of Alice and Bob
Short extract from after-dinner speech by John Gordon at The Zurich Seminar, April 1984

I go to lots of conferences on coding theory in which complicated protocols get discussed. You know the sort of thing:

A communicates with someone who claims to be B.
So to be sure, A tests that B knows a secret number K.
So A sends to B a random number X.
B then forms Y by encrypting X under key K and sends Y back to A.

and so on. Because this sort of thing is is quite hard to follow, a few years ago theorists stopped using the letters A and B to represent the main players, and started calling them Alice and Bob. So now we say

Alice communicates with someone claiming to be Bob.
So to be sure, Alice tests that Bob knows a secret number K.
Alice sends to Bob a random number X.
Bob then forms Y by encrypting X under key K and sends Y back to Alice.

It's supposed to make it easier to understand.

Now there are hundreds and hundreds of papers written about Alice and Bob. Alice and Bob have been used to illustrate all sorts of protocols and bits of coding theory in scientific papers. Over the years Alice and Bob have tried to defraud insurance companies, they've exchanged secret messages over a tapped line, and the've played poker for high stakes by mail. Now if we put together all the little details from lots of papers -- a snippet from here, a snippet from there -- we get a facinating picture of their lives. This may be the first time in the history of coding theory that a definitive biography of Alice and Bob has been given.

Take Bob. Bob is often selling securities to speculators so we can be pretty sure he's a stockbroker. But from his concern about eavesdropping he is probably into something subersive on the side too. Take Alice. From the number of times Alice tries to buy stock from him we can say she is probably a speculator. And she's also worried that her husband doesn't get to find out about her financial dealings. So Bob is a subversive stockbroker and Alice is a two-timing speculator.

But Alice has a number of serious problems. She and Bob only get to talk by telephone or by email. And in the country where they live the phone service is very expensive. And Alice and Bob are cheapskates. So the first thing Alice must do is minimize the cost of the phone call.

The telephone in their country is also pretty lousy. The interference is so bad that Alice and Bob can hardly hear each other. So the second thing Alice must do is to protect her messages against errors in transmission.

On top of that Alice and Bob have very powerful enemies. One of their enemies the is the Tax Authority. Another is the Secret Police. These enemies have almost unlimited resources. They always listen in to telephone conversations between Alice and Bob. This is a pity since Bob and Alice are always plotting tax frauds and overthrowing the government. So the third thing Alice must do is protect her communications from eavesdropping.

And these enemies are very sneaky. One of their favourite tricks is to telephone Alice and pretend to be Bob. So the fourth thing Alice has to do is to be sure she is communicating with whom she thinks she is. Well, you think, so all Alice has to do is listen very carefully to be sure she recognises Bob's voice. But no. You see Alice has never met Bob. She has no idea what his voice sounds like.

All in all Alice has a whole bunch of problems. Oh yes, and there is one more thing I forgot so say: Alice doesn't trust Bob. 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 can't hear clearly, and who is probably someone else, to fiddle her tax return and to organise a cout d'etat, while at the same time minimising the cost of the phone call.

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

(C) John Gordon 1984
Source: http://web.mit.edu/jemorris/humor/alice-and-bob

[SteveRiley]

Also:

[GreyGeek]

Steve, I see a book about security in your future! With stuff you've talked about on this forum and only you know what else.
Do it before I die!

[SteveRiley]

Steve, I see a book about security in your future! With stuff you've talked about on this forum and only you know what else.

Did that. Once is enough...

[GreyGeek]

Did that. Once is enough...

Actually, I read that!

How about one written around the use of Linux?

[SteveRiley]

Thank you! Oddly enough, I still get royalty checks. Like $30 to $50 every six months. Who's still buying the thing? LOL

[Qqmike]

Steve, actually, your publisher can provide you with a list of sales by name and location. Mine trickled down like yours, generating small checks for many years, and from all over the place (Philippines, Canada, Mexico, ...). Then friends from around the country would tell me they picked up a used copy here or there! Then I thought it was totally dead. Now today, I googled, and it is all over the place (dead, but still alive).
https://www.google.com/search?client...utf-8&oe=utf-8
http://www.amazon.com/Quantitative-m.../dp/0818504358
The Product Details is wrong though--it is 623 pages plus the 120-page Appendix (numbered A1-A120, which, maybe, is where Amazon got the 120). And, of course, they have no actual photo of the real cover.


Edit: I had Amazon change the page count to 743, fwiw; takes 2-3 days. Edit: they made the change effective almost immediately.

[MoonRise]

No Bio?

[Qqmike]

Ah, you want Bio? How about, mathematician in drag?

[MoonRise]

[woodsmoke]

Nick, your video, in my particular part of the space time continuum has been subjected to what was first started under Bush and then completed under Obama. in the name of national security for megacorporations....

WMG and UMPG publishing..i can't open it due to copyright restrictions. lol

woodsmoke

[SteveRiley]

subjected to what was first started under Bush and then completed under Obama

You do realize that the executive of either party bears little responsibility here. It's a compliant Congress, purchased by moneyed interests, that shoulders the blame.

[MoonRise]

...... purchased by moneyed interests,.......

Right on that!

[GreyGeek]

Exactly, Steve!
We have the best Congress money can buy, and that is the problem. They are all bought and paid for and they don't give a hoot about the wishes of the American citizens. Almost all of them (Congress AND the Senate AND the Executive) could be impeached for violation of their oath of office.