Traveller Store CotI Features New Posts Mark Forums Read Register


Go Back TravellerRPG.com > Citizens of the Imperium > General Traveller Discussions > The Lone Star

The Lone Star Meet, greet and socialize with your fellow Travellers in the Lone Star Lounge. Random Topics.

Reply
 
Thread Tools Display Modes
  #1  
Old January 7th, 2014, 10:37 PM
SpaceBadger's Avatar
SpaceBadger SpaceBadger is offline
Citizen: SOC-14
 
Join Date: Jan 2013
Location: Central Missouri, USA
Posts: 3,585
Gallery : 1
Visit SpaceBadger's Blog
SpaceBadger Respected CitizenSpaceBadger Respected CitizenSpaceBadger Respected CitizenSpaceBadger Respected CitizenSpaceBadger Respected CitizenSpaceBadger Respected Citizen
Default Secure communications?

We just had a bit in SBRD in which the characters on shipboard are arranging for laser communication with a character on a moon 12 million km away, to keep their discussions secure.

After posting that, it occurred to me that with laser beam spread over that distance, it might not be too difficult for someone else to also have a receiver in the path of the beam, so to make it actually secure they need encryption.

Problem is, these people have been out of touch for some period of time, so would not have been able to share any encryption keys.

Would someone more knowledgeable than I about public/private key encryption answer a couple of questions for me?

1) Would it work for them to just exchange their public keys in the clear, then be able to encrypt from that point forward, or would that also allow any listener to decrypt as well?

2) Would it work for everyone just to use their commcode as their public key, so no need to even exchange? Or is there some other component that must be exchanged other than the public key?
__________________
--
Q: What do you get when you vaporize a Duke, a Count, a Marquis, and a Baron?
A: Helium, Neon, Argon, Krypton, Xenon, and Radon


Imperial Core Update: In other news, Emperor Strephon Aella Alkhalikoi is... still alive.

My Old Stuff (2013-14)
SBRD Campaign Quick Reference
SBRD Campaign Wiki: Reavers' Deep during The Long Night
Reply With Quote
  #2  
Old January 7th, 2014, 11:49 PM
Lycanorukke Lycanorukke is offline
Citizen: SOC-13
 
Join Date: Apr 2009
Posts: 574
Gallery : 0
Lycanorukke Citizen+Lycanorukke Citizen+Lycanorukke Citizen+
Default

Quote:
Originally Posted by SpaceBadger View Post
1) Would it work for them to just exchange their public keys in the clear, then be able to encrypt from that point forward, or would that also allow any listener to decrypt as well?
When a 'public' key is generated, at the same time a 'private' key is generated.
A transmission is encrypted using the public key, and (theroetically) only the person with the matching private key and decrypt it.

Fred generates a public/private key pair.
Fred transmitts public key to Sue
Evil villian can see the public key.
Sue writes a message and encrypts it using Freds public key.
Sue transmits the message.
Evil villian intercepts message.
Fred decodes the message using his private key
Evil villian cant decrypt the message as he doesn't have Freds private key
Sue can't decrypt the message once she has sent it, even though she wrote it. Only Freds private key can do that

The main catch is that the system can be brute forced cracked, and with high tech computers you could crack simple keys very fast. There are also other mathematical tricks which can be used but they tend to be specific to certain types of encryption program.

Of course if they are using a common standard bit of software 'out of the box' it is possible it has already been 'cracked' by someone. Or if they are clever they arrange a 'man in the middle' attack (villian captures the public key transmission, makes his own keys, and re-transmits so Fred and Sue think they have the others public keys, but in reality the villian is 'relaying' the messages). That way the villian interepts the message, reads it, re-encrytps and transmits it on.

Quote:
2) Would it work for everyone just to use their commcode as their public key, so no need to even exchange? Or is there some other component that must be exchanged other than the public key?
No other components need be exchanged. However I doubt a public com number would suffice as a key. The prevent easy brute force attacking you need long numbered keys. Current PGP is around 256 bits are people are looking at 512, so with H-tech massively parallel computers you would need massively long numbers. I doubt even spacers could remember a multi-mega bit "phone number".

On edit: My party used something like a book cipher. They all kept an old ratty copy of 'The scouts manual' or 'Tourists guide to Regina' (or some other obscure boring book) and then transmitted strings of numbers corresponding to words in the book. Unless evil villian knew about the books they couldn't decrypt the number strings. A dedicated crypto computer could probably crack it (one pre loaded with common books to compare with), but in emergencies against ordinary opponents it was fine.
Reply With Quote
  #3  
Old January 8th, 2014, 12:01 AM
SpaceBadger's Avatar
SpaceBadger SpaceBadger is offline
Citizen: SOC-14
 
Join Date: Jan 2013
Location: Central Missouri, USA
Posts: 3,585
Gallery : 1
Visit SpaceBadger's Blog
SpaceBadger Respected CitizenSpaceBadger Respected CitizenSpaceBadger Respected CitizenSpaceBadger Respected CitizenSpaceBadger Respected CitizenSpaceBadger Respected Citizen
Default

OK, so if I understand your example, the answer to Q1 is Yes, but with a few weaknesses?

So they could just exchange public keys in their first comm, then after that use encrypted comms over the public system. Using the laser to restrict the signal is just an added bit of security to limit potential listeners.

Thanks!
__________________
--
Q: What do you get when you vaporize a Duke, a Count, a Marquis, and a Baron?
A: Helium, Neon, Argon, Krypton, Xenon, and Radon


Imperial Core Update: In other news, Emperor Strephon Aella Alkhalikoi is... still alive.

My Old Stuff (2013-14)
SBRD Campaign Quick Reference
SBRD Campaign Wiki: Reavers' Deep during The Long Night
Reply With Quote
  #4  
Old January 8th, 2014, 12:12 AM
tjoneslo tjoneslo is offline
Citizen: SOC-14
 
Join Date: Feb 2001
Location: Ferrisburgh, VT, USA
Posts: 2,892
Gallery : 2
Visit tjoneslo's Blog
tjoneslo Citizen+tjoneslo Citizen+tjoneslo Citizen+
Default

Quote:
Originally Posted by SpaceBadger View Post
OK, so if I understand your example, the answer to Q1 is Yes, but with a few weaknesses?

So they could just exchange public keys in their first comm, then after that use encrypted comms over the public system. Using the laser to restrict the signal is just an added bit of security to limit potential listeners.

Thanks!
If you are using a computer controlled communications system, the "first comm" to transmit (and acknowledge) the public keys and establish the secured communication channel can be automated. If you assume this, there are several complex processes regarding establishing secured communications which ensure both people at either end are talking to the people they intend to. And not any bad guys.

The term you are looking for is called a "man in the middle attack" in the security realm. This is a well studied problem in secured communications over a channel (like a radio) which may have others listening in.

I generally assume by the 57th century, establishing a secure, encrypted channel over a pair of communicators is a solved problem.
__________________
Archduke of the Solomani Rim - Terra (Solomani Rim 1827)
Duke Akumid - Akumid (Vland 1628)
Marquis Yeremyh - Yeremyh (Solomani Rim 1804)
Marquis Hysyl - Hysyl (Deneb 2425)
Baron Regina - Regina (Spinward Marches 1910)
TAS member - Vipan (Empty Quarter 1038)
Be part of the history of Traveller:

https://wiki.travellerrpg.com/Main_Page
Reply With Quote
  #5  
Old January 8th, 2014, 12:20 AM
Lycanorukke Lycanorukke is offline
Citizen: SOC-13
 
Join Date: Apr 2009
Posts: 574
Gallery : 0
Lycanorukke Citizen+Lycanorukke Citizen+Lycanorukke Citizen+
Default

Quote:
Originally Posted by SpaceBadger View Post
OK, so if I understand your example, the answer to Q1 is Yes, but with a few weaknesses?

So they could just exchange public keys in their first comm, then after that use encrypted comms over the public system. Using the laser to restrict the signal is just an added bit of security to limit potential listeners.

Thanks!
Sorry for rambling on, it is a painfully mathematically complicted subject under the hood.

But if they are worried about Joe Public, the KeyStone Kops, or Billy Bob the pirate listening in, the keys would be fine. If they are worried about a spook agency listing in, it could be more problematic.

The other is the tech difference. If they are using a TL 10 encryptor, someone with a TL15 decryptor woud probably laugh at them. If they use a T-15 encryptor, I doubt a T-10 decryptor would crack it in a 100 years.

Last edited by Lycanorukke; January 8th, 2014 at 12:32 AM..
Reply With Quote
  #6  
Old January 8th, 2014, 01:15 AM
Vladika Vladika is offline
Citizen: SOC-14
 
Join Date: Jun 2008
Posts: 1,851
Gallery : 0
Vladika Citizen++Vladika Citizen++Vladika Citizen++Vladika Citizen++Vladika Citizen++
Default

Cyphers can, sooner or later, be broken. Codes can not. In the above example, the scout manual was used as a "one time pad". These are still considered one of the safest methods. It is random and even can have successive substitutions within. It requires both parties to have identical copies.

This can be a problem but both parties can use a "code" based on a shared common experience or understanding to mutually establish what common text to use. It isn't hard to do if both have even a rudimentary understanding of the process.

Also, does it have to hold up for a few days, hours, weeks, months, years or forever? If it doesn't matter if it is cracked after a certain time then no real problem.
__________________
“All animals are equal, but some animals are more equal than others.” - George Orwell, Animal Farm ;)

:oo: “The creatures outside looked from pig to man, and from man to pig, and from pig to man again; but already it was impossible to say which was which.” - George Orwell, Animal Farm :devil:

Lord Michael - Heretic
Baron Emape
Spinward Marches, Five Sisters, 0133 B564500-B

Last edited by Vladika; January 8th, 2014 at 02:32 AM..
Reply With Quote
  #7  
Old January 8th, 2014, 02:25 AM
aramis's Avatar
aramis aramis is offline
Administrator
 
Join Date: May 2001
Location: Anchorage, AK, USofA
Posts: 29,420
Gallery : 56
Visit aramis's Blog
aramis has disabled reputation
Send a message via ICQ to aramis Send a message via AIM to aramis Send a message via Yahoo to aramis
Default

Quote:
Originally Posted by SpaceBadger View Post
OK, so if I understand your example, the answer to Q1 is Yes, but with a few weaknesses?

So they could just exchange public keys in their first comm, then after that use encrypted comms over the public system. Using the laser to restrict the signal is just an added bit of security to limit potential listeners.

Thanks!
just remember: the more often given key is used, the more data is available to analyze, and the more likely they can crack it.

Also, you don't want to make the public key public, either. Given the public key, interceptor guy can run certain known samples, analyze the output, and engjneer a private key from it.
__________________
~ Aramis
aramis.hostman.us /trav
Smith & Wesson: The Original Point and Click interface!

Archduke of Sylea (CORE 2118)
Duke of the Third Imperium (SPIN 0534)
Count Terra (SOLO 1827)
Count Gorod (REFT 1302)
Count of the Third Imperium (SPIN 2232)
Viscount of Adabicci (SPIN 1824)
Marquis of the Solomani Rim (SOLO 0606)
Marquis of the Third Imperium (SPIN 2410)
Baron of the Third Imperium (SPIN 2231)
Knight of the Iridium Throne (CORE 1434)
Sir William Hostman (OLDE 0512)
Sir William Hostman (DAGU 0622)
Knight of Deneb (REFT 2239)
Knight of Deneb (Spin 2532)
SEH w/Diamonds for Extreme Heroism - Battle of Boughene
MCG - Battle of Boughene
TAS: William Hostman (CORR 2506)
TAS: Bearer (DAIB 1326)
IMTU ct+ tm++ tne tg-- tt+ tmo+ t4- t20+ to ru+ ge+ 3i+ c+ jt au ls pi+ ta he+ st+
Wil Hostman 0602 C539857-9 S A724
OTU: 95% 3i an+ au+ br- cpu± dt± f+ fs++ ge± ih- inf± j± jf+ jm+ jt+ ls- n= nc+ pi+ pp-- tp+ tr+ tv- vi-- xb+-
Unless there is bold red text, presume my posts to be my personal material only.
Reply With Quote
  #8  
Old January 8th, 2014, 12:34 PM
tjoneslo tjoneslo is offline
Citizen: SOC-14
 
Join Date: Feb 2001
Location: Ferrisburgh, VT, USA
Posts: 2,892
Gallery : 2
Visit tjoneslo's Blog
tjoneslo Citizen+tjoneslo Citizen+tjoneslo Citizen+
Default

Quote:
Originally Posted by aramis View Post
just remember: the more often given key is used, the more data is available to analyze, and the more likely they can crack it.

Also, you don't want to make the public key public, either. Given the public key, interceptor guy can run certain known samples, analyze the output, and engjneer a private key from it.
Right, with an automated system the connection protocol encrypts a seed value, then the comm system at either end generates an symmetric key based upon the seed value using a different encryption scheme. And then automatically generates a new key periodically. For the truly paranoid you would do this for every packet of data sent. And each encrypted packet contains updated values for encryption key seed generated from a true random number generator.
__________________
Archduke of the Solomani Rim - Terra (Solomani Rim 1827)
Duke Akumid - Akumid (Vland 1628)
Marquis Yeremyh - Yeremyh (Solomani Rim 1804)
Marquis Hysyl - Hysyl (Deneb 2425)
Baron Regina - Regina (Spinward Marches 1910)
TAS member - Vipan (Empty Quarter 1038)
Be part of the history of Traveller:

https://wiki.travellerrpg.com/Main_Page
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Secure Facility Request Icosahedron The Lone Star 3 September 21st, 2009 03:46 PM
Secure Server Ordering Up and Running! hunter Citizens' Information Centre 0 February 24th, 2008 04:24 PM
Secure Credit Card Ordering Back Up hunter Citizens' Information Centre 0 August 8th, 2007 01:41 AM
Secure Server Cert Back in Place hunter The Lone Star 1 May 25th, 2002 02:05 AM
Secure Server Cert Back in Place hunter T20 - Traveller for the D20 System 0 May 24th, 2002 03:42 PM

This website and its contents are copyright ©2010- Far Future Enterprises. All rights reserved. Traveller is a registered trademark of Far Future Enterprises .
Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Copyright (c) 2010-2013, Far Future Enterprises. All Rights Reserved.