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Who can (re)explain public key encryption for me?

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darkstar Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Dec-27-04 05:58 PM
Original message
Who can (re)explain public key encryption for me?
An out of town friend explained it to me about 2 years ago and I'm pretty sure I really understood the concept. But I brought it up today at work and when someone asked "How does it work?" I felt like an utter moran. Couldn't even begin to answer....

New wrinkles in the last two years, if PKE has been dropped in favor of some hot new apprach, all related info would be great, too.

Thanks in advance.

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miss_kitty Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Dec-27-04 06:01 PM
Response to Original message
1. Is this what you want?
http://www.webopedia.com/TERM/P/public_key_cryptography...

"A cryptographic system that uses two keys -- a public key known to everyone and a private or secret key known only to the recipient of the message. When John wants to send a secure message to Jane, he uses Jane's public key to encrypt the message. Jane then uses her private key to decrypt it.

An important element to the public key system is that the public and private keys are related in such a way that only the public key can be used to encrypt messages and only the corresponding private key can be used to decrypt them. Moreover, it is virtually impossible to deduce the private key if you know the public key."
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Florida_Geek Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Dec-27-04 06:01 PM
Response to Original message
2. Good example
from http://www.webopedia.com/TERM/P/public_key_cryptography...

A cryptographic system that uses two keys -- a public key known to everyone and a private or secret key known only to the recipient of the message. When John wants to send a secure message to Jane, he uses Jane's public key to encrypt the message. Jane then uses her private key to decrypt it.

An important element to the public key system is that the public and private keys are related in such a way that only the public key can be used to encrypt messages and only the corresponding private key can be used to decrypt them. Moreover, it is virtually impossible to deduce the private key if you know the public key.

Public-key systems, such as Pretty Good Privacy (PGP), are becoming popular for transmitting information via the Internet. They are extremely secure and relatively simple to use. The only difficulty with public-key systems is that you need to know the recipient's public key to encrypt a message for him or her. What's needed, therefore, is a global registry of public keys, which is one of the promises of the new LDAP technology.

Public key cryptography was invented in 1976 by Whitfield Diffie and Martin Hellman. For this reason, it is sometime called Diffie-Hellman encryption. It is also called asymmetric encryption because it uses two keys instead of one key (symmetric encryption).
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miss_kitty Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Dec-27-04 06:02 PM
Response to Reply #2
3. hahahahahaha!
we're so smart!
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Florida_Geek Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Dec-27-04 06:03 PM
Response to Reply #3
4. lol
minds that think alike....
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Dr Batsen D Belfry Donating Member (650 posts) Send PM | Profile | Ignore Mon Dec-27-04 06:04 PM
Response to Original message
5. PPK Encryption
Edited on Mon Dec-27-04 06:05 PM by Dr Batsen D Belfry
is based on an algorithm where one key (private) can encrypt data, and the other (public) can decrypt it. Both are derived at the same time and can be used in reverse.

I generate a PPK pair. I keep the private key, and put the public key on my SSH server, which uses it to authenticate me. My password is encrypted using my public key and the server uses my private key to decrypt it.

PGP operates this way using public key servers

On edit: DAMN you folks are FAST!

DBDB
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darkstar Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Dec-27-04 06:14 PM
Response to Reply #5
7. Good Dr. Belfry
Can you expand on this in greater detail?

"I generate a PPK pair. I keep the private key, and put the public key on my SSH server, which uses it to authenticate me. My password is encrypted using my public key and the server uses my private key to decrypt it."

I swear, if I don't get it on the next pass, I won't pester you again.


Thank, perfesser!!!!!!!!!!!!!
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Dr Batsen D Belfry Donating Member (650 posts) Send PM | Profile | Ignore Mon Dec-27-04 06:53 PM
Response to Reply #7
8. Let's start at the beginning, shall we?
Edited on Mon Dec-27-04 07:04 PM by Dr Batsen D Belfry
What exactly are you using this for? Pretty Good Privacy (PGP) for email? Secure Shell (SSH) for connecting to remote servers? Communicating in general with friends without the intrusion from *Bush and his merry band of eavesdroppers? Something else?

The solution you seek is dependent upon your usage

If you want to see how it works under the hood, here is a start
http://www.math.nmsu.edu/crypto/public_html/PublicKey.h...
http://www.math.nmsu.edu/crypto/public_html/BegRSA.html

DBDB
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darkstar Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Dec-27-04 07:06 PM
Response to Reply #8
10. Well...
I just want to understand it...again. That simple.

I remember being facinated by the concept. But, too me at least, it's one of those things that's slippery. (Another one is the "let's make deal" Monte Carlo simulation discussed here in the lounge about 2 weeks ago....)

I'm sorry if I'm not posing the question correctly, but here goes:

I "broadcast" an encoding key for all to see. You encode w/ that algorithm and transmit in semi-public, cough, email to me. Let's stop there (and maybe it will answer the obvious follow up question): How come eavesdroppers can't decode it when they have acess to the way it was encoded?

Thanks very much. Sincerely.

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darkstar Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Dec-27-04 07:09 PM
Response to Reply #10
11. OK, thanks
You added links while I was responding....

And yes, I guess I want the hood cracked open a couple of inches. Certainly not the whole way,

Thanks again

:cheers:
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darkstar Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Dec-27-04 06:12 PM
Response to Original message
6. Thanks to all
It's coming back. Slowly. One key is and public, one is private.

But I guess I'm still in the dark as to the encryption/decryption details, the real specifics of the process.

Anyone?

Again, thanx for getting me this far. One cylinder just fired, I think...
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BeTheChange Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Dec-27-04 06:55 PM
Response to Reply #6
9. Too bad it will be illegal soon..
Coming to you courtesy of Patriot Act 2.
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darkstar Donating Member (1000+ posts) Send PM | Profile | Ignore Mon Dec-27-04 07:17 PM
Response to Reply #9
12. Oh really
Our talk today was not based on that at all. Now I have another whole basket of questions. One is, how can it be enforced?
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BeTheChange Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Dec-28-04 01:11 PM
Response to Reply #12
13. Domestic Security Enhancement Act 2003
-Creating a new, separate crime of using encryption technology that could add five years to any sentence for crimes committed with a computer. (Section 404)

http://www.aclu.org/SafeandFree/SafeandFree.cfm?ID=1183...

Heaven forbid if we start organizing on the Net.
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