Post-quantum cryptography
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Post-quantum cryptography
1–10 of 23 posts
Re: Post-quantum cryptography
#2Q: Why should we care about this? Why not deal with it when quantum computers finally start cracking existing crypto?
A:
1. It takes time to implement new methods. Would it be acceptable for there to be a period of months or years during which we can't make credit card transactions, etc.?
2. Coded text of messages encoded using conventional cryptographic methods can be intercepted, archived and then broken at a later date. If you make a purchase today, somebody archives the coded exchange, and a quantum computer capable of cracking the encryption used in that exchange becomes available before your credit card expires, you've got a problem. You've got an even bigger problem if you transmit information that remains sensitive for longer than your credit card info.
As a general rule, don't use conventional encryption methods to transmit information with long-term sensitivity (e.g. medical records, etc.).
Re: Post-quantum cryptography
#3Q: Why should we care about this? Why not deal with it when quantum computers finally start cracking existing crypto? A: 1. It takes time to implement new methods. Would it be acceptable for there to be a period of months or years during which we can't make credit card transactions, etc.? 2. Coded text of messages encoded using conventional cryptographic methods can be intercepted, archived and then broken at a later…
> As a general rule, don't use conventional encryption methods to transmit information with long-term sensitivity (e.g. medical records, etc.).
So what do you suggest I use today, given that I have a medical record here and I need it over there?
Re: Post-quantum cryptography
#4By the way, this is a pretty good intro to post-quantum crypto if you are more mathy.
The NSA announced they will be transitioning to quantum resistant algorithm in the "not to distant future".
https://www.nsa.gov/ia/programs/suiteb_cryptography/index.sh...
So this is something that may be getting a lot more press in the...not to distant future.
Re: Post-quantum cryptography
#5Q: Why should we care about this? Why not deal with it when quantum computers finally start cracking existing crypto? A: 1. It takes time to implement new methods. Would it be acceptable for there to be a period of months or years during which we can't make credit card transactions, etc.? 2. Coded text of messages encoded using conventional cryptographic methods can be intercepted, archived and then broken at a later…
> As a general rule, don't use conventional encryption methods to transmit information with long-term sensitivity (e.g. medical records, etc.). So what do you suggest I use today , given that I have a medical record here and I need it over there?
One time pads sent via some secure service is about all I can come up with. This works provided you know who you are going to talk to and don't suddenly run out of "pad". Sounds like an awful business model. I'm sure some consultancy could sell it though.
Re: Post-quantum cryptography
#6Q: Why should we care about this? Why not deal with it when quantum computers finally start cracking existing crypto? A: 1. It takes time to implement new methods. Would it be acceptable for there to be a period of months or years during which we can't make credit card transactions, etc.? 2. Coded text of messages encoded using conventional cryptographic methods can be intercepted, archived and then broken at a later…
> As a general rule, don't use conventional encryption methods to transmit information with long-term sensitivity (e.g. medical records, etc.). So what do you suggest I use today , given that I have a medical record here and I need it over there?
My current, somewhat underinformed understanding:
(A) Handling key exchange (Diffie-Hellmman) is ugly. There are other algorithms, but I'm unclear what a good choice is right now. I'm also unclear if larger key sizes are actually helpful. (B) For symmetric algorithms, AES, use AES-256. In the quantum case, it might be equivalent to ~127-128 bit AES, which is pretty decent. (C) For hashing, use SHA-512. It uses 64-bit words, and might be similar in strength to SHA-256 today. (D) A lot of hash algorithms can actually be used as signature schemes, especially if you combine them with Merkle tree like structures.
Re: Post-quantum cryptography
#7Q: Why should we care about this? Why not deal with it when quantum computers finally start cracking existing crypto? A: 1. It takes time to implement new methods. Would it be acceptable for there to be a period of months or years during which we can't make credit card transactions, etc.? 2. Coded text of messages encoded using conventional cryptographic methods can be intercepted, archived and then broken at a later…
> As a general rule, don't use conventional encryption methods to transmit information with long-term sensitivity (e.g. medical records, etc.). So what do you suggest I use today , given that I have a medical record here and I need it over there?
[deleted]
Re: Post-quantum cryptography
#8Earlier quoted context omitted.
> As a general rule, don't use conventional encryption methods to transmit information with long-term sensitivity (e.g. medical records, etc.). So what do you suggest I use today , given that I have a medical record here and I need it over there?
One time pads sent via some secure service is about all I can come up with. This works provided you know who you are going to talk to and don't suddenly run out of "pad". Sounds like an awful business model. I'm sure some consultancy could sell it though.
Post-quantum crypto already exists afaik, the only issue is performance and key sizes (I guess this supposes the of quantum difficulty of certain problems).
Re: Post-quantum cryptography
#9Earlier quoted context omitted.
> As a general rule, don't use conventional encryption methods to transmit information with long-term sensitivity (e.g. medical records, etc.). So what do you suggest I use today , given that I have a medical record here and I need it over there?
One time pads sent via some secure service is about all I can come up with. This works provided you know who you are going to talk to and don't suddenly run out of "pad". Sounds like an awful business model. I'm sure some consultancy could sell it though.
One time pads offer zero integrity/authentication. They are "malleable".
Re: Post-quantum cryptography
#10Earlier quoted context omitted.
One time pads sent via some secure service is about all I can come up with. This works provided you know who you are going to talk to and don't suddenly run out of "pad". Sounds like an awful business model. I'm sure some consultancy could sell it though.
Post-quantum crypto already exists afaik, the only issue is performance and key sizes (I guess this supposes the of quantum difficulty of certain problems).
It's not enough to have an algorithm. You need to get down to "what do these bytes mean" and "what exactly do I do with them" and have that be implemented. It's a considerably more painful process than you might think if you haven't been exposed to IETF things.