Practice Cryptography!
Even with all of the cryptologic and cryptographic technology that has existed in the world for the past 60 years, we still don't really know what encryption is good for or how to use it -- or, more importantly, why it's important. Maybe it's time for people and coders to actually start practicing how to use it, like any other skill.Friday, January 18, 2008
Identity
If you receive a message encrypted with a certain public key that you've seen before, you can safely assume that the same private key was used to encrypt that message as was used before. If we can assume 'proper' key management procedures, we can assume that the same person used the same private key to encrypt that message.
This provides for referential continuity.
If we know that we're dealing with the same entity (key) as before... why do we need to know who that entity is? Should we need to? If so, why?
(Imagine a site that provides relatively static content with updates from time to time. Why should that site need to know that Joe Bloe from Elgin IL is accessing it? Instead, why not reduce that knowledge to 'a key which has been approved to access the site until X date was used to access the site'? Combine that with the IP address, and you have a means of making sure that the key isn't improperly distributed.)
This provides for referential continuity.
If we know that we're dealing with the same entity (key) as before... why do we need to know who that entity is? Should we need to? If so, why?
(Imagine a site that provides relatively static content with updates from time to time. Why should that site need to know that Joe Bloe from Elgin IL is accessing it? Instead, why not reduce that knowledge to 'a key which has been approved to access the site until X date was used to access the site'? Combine that with the IP address, and you have a means of making sure that the key isn't improperly distributed.)
What do we need to identify and authenticate?
When we're using cryptography, what do we need to identify and authenticate?
Some folk think that by applying a digital signature to something, it's the same as a physical, handwritten signature. Yet, there's no legal reason for this (except perhaps the digital signatures act, which allows for certain digital signatures to be recognized in certain transactions -- but which doesn't assign any meaning to any other digital signature).
I think that there are things that cryptography would be good for, and it's very important to realize that we've got problems in the real world right now that cryptography can solve even without legal recognition.
The Cypherpunks (site http://www.cypherpunks.ca/ ) created OTR -- "Off The Record". This allows for verification of received messages at the time of receipt, without any kind of verifiable log. This means that your conversation is private while it's going on, and also means that either end can forge messages in their own logs. This is perfect from a conversational privacy standpoint, as it re-introduces the concept of "he said she said" -- I have deniability of anything I say to you, and vice versa. It can't be proven that I (or you) actually said anything, so cryptography is made less scary to use.
This is the kind of thing that we need to see more of. Instead of letting the governmental bureaucrats who created X.509 and pushed it on us dictate how cryptography must be used... we should find our own ways to use it, for the purposes that we want and that we intend.
Some folk think that by applying a digital signature to something, it's the same as a physical, handwritten signature. Yet, there's no legal reason for this (except perhaps the digital signatures act, which allows for certain digital signatures to be recognized in certain transactions -- but which doesn't assign any meaning to any other digital signature).
I think that there are things that cryptography would be good for, and it's very important to realize that we've got problems in the real world right now that cryptography can solve even without legal recognition.
The Cypherpunks (site http://www.cypherpunks.ca/ ) created OTR -- "Off The Record". This allows for verification of received messages at the time of receipt, without any kind of verifiable log. This means that your conversation is private while it's going on, and also means that either end can forge messages in their own logs. This is perfect from a conversational privacy standpoint, as it re-introduces the concept of "he said she said" -- I have deniability of anything I say to you, and vice versa. It can't be proven that I (or you) actually said anything, so cryptography is made less scary to use.
This is the kind of thing that we need to see more of. Instead of letting the governmental bureaucrats who created X.509 and pushed it on us dictate how cryptography must be used... we should find our own ways to use it, for the purposes that we want and that we intend.
How to solve the crypto problem (i.e., no one uses it)
The only way to solve the crypto problem is to make it so pervasive and transparent that people don't realize they're using it.
How are we supposed to do this? Well, we have to make it invisible, we have to make it useful, and we have to change our assumptions about what cryptography means when it's in use.
We also have to change our assumptions about authentication, and what precisely we're authenticating.
How are we supposed to do this? Well, we have to make it invisible, we have to make it useful, and we have to change our assumptions about what cryptography means when it's in use.
We also have to change our assumptions about authentication, and what precisely we're authenticating.
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