Bruce Schneier has changed his PGP key to 4096 bits • Hacker News Board

Re: Bruce Schneier has changed his PGP key to 4096 bits

#31

Post by pndmnm » Thu, Sep 12, 2013, 10:43 PM UTC

malandrew wrote: post #28

michiel3 wrote: post #25

In the post he also describes that he now uses a new process which involves a computer that has never been connected to the internet and its sole purpose is encrypting and decrypting files. Why not use it to encrypt and decrypt emails as well? That'd also potentially involve generating a new key pair. > 3) Assume that while your computer can be compromised, it would take work and risk on the part of the NSA – so it p…

With linux, is there any way to compromise the USB stick used for the air gap? AFAIK the Stuxnet virus was originally spread via USB stick, however I reckon that it involved Windows machines that are known to execute files on USB sticks.

Years ago, a classmate of mine built a rig out of a receipt printer and one of those old handheld scanners to provide an "air gap", though it never really worked (sort of an art project at the time). Might be time to revive the idea...

Re: Bruce Schneier has changed his PGP key to 4096 bits

#32

Post by miloshadzic » Thu, Sep 12, 2013, 10:44 PM UTC

tptacek wrote: post #18

knowtheory wrote: post #10

Earlier quoted context omitted.

Normally i'd let it go, but i actually would like some clarity on your intent here. Are you implying that Schneier doesn't use encrypted communications on a regular basis, that PGP is impractical, or both? (and to be clear, my intent is not to bait, i'm actually curious)

Most people don't use PGP on a regular basis. I'm use PGP a lot, more than I think most HN readers, but most of the people I talk to (even in my own field, which is full of secrets and adversaries) don't have PGP keys.

Does the reason for that ever come up in a conversation? I thought that everyone working in security used PGP a lot.

Re: Bruce Schneier has changed his PGP key to 4096 bits

#33

Post by malandrew » Thu, Sep 12, 2013, 10:44 PM UTC

vabmit wrote: post #22

mrjj wrote: post #13

Is he really afraid of 2^n/2 brute power of quantum computers or this is just overkilling of overkill?

There's no need for a quantum computer. Everyone should be using at least 4096bit RSA. 1024bit RSA keys can be factored with conventional non-specialized hardware (read: CPU's, not even GPU's) with GNFS. IMHO, 2048bit RSA keys can be factored by custom hardware that the NSA has developed. I posted my reasoning for this hypothesis in other hackernews threads. A very quick/terse run down of the main key points - 1) NSA…

IIRC some piece of news surrounding all this stated that the NSA considers anyone using cryptography to protect their communications to be people of interest, whose dragnetted correspondence will be stored indefinitely. I'm curious if the NSA prioritizes these people according to how strong their keys are. I imagine that the logic would be that someone using 4096bit keys is either paranoid or really really has something to hide.

Re: Bruce Schneier has changed his PGP key to 4096 bits

#34

Post by betterunix » Thu, Sep 12, 2013, 10:45 PM UTC

malandrew wrote: post #28

michiel3 wrote: post #25

In the post he also describes that he now uses a new process which involves a computer that has never been connected to the internet and its sole purpose is encrypting and decrypting files. Why not use it to encrypt and decrypt emails as well? That'd also potentially involve generating a new key pair. > 3) Assume that while your computer can be compromised, it would take work and risk on the part of the NSA – so it p…

With linux, is there any way to compromise the USB stick used for the air gap? AFAIK the Stuxnet virus was originally spread via USB stick, however I reckon that it involved Windows machines that are known to execute files on USB sticks.

I think some basic opsec is in order here. The airgapped computer should format every thumb drive plugged into it, or even better, should ignore any USB device that is not the specific thumb drive you are using. All of this could be configured without terribly much pain (which is not to say it is trivial) in GNU/Linux. Not perfect, of course, but would stop quite a few attacks and reduce the chance of carelessness screwing up security.

Re: Bruce Schneier has changed his PGP key to 4096 bits

#35

Post by betterunix » Thu, Sep 12, 2013, 10:47 PM UTC

vabmit wrote: post #22

mrjj wrote: post #13

Is he really afraid of 2^n/2 brute power of quantum computers or this is just overkilling of overkill?

There's no need for a quantum computer. Everyone should be using at least 4096bit RSA. 1024bit RSA keys can be factored with conventional non-specialized hardware (read: CPU's, not even GPU's) with GNFS. IMHO, 2048bit RSA keys can be factored by custom hardware that the NSA has developed. I posted my reasoning for this hypothesis in other hackernews threads. A very quick/terse run down of the main key points - 1) NSA…

I think it is a bit of a stretch to say that 2048 bit keys can be factored with NSA resources unless the NSA also has a more efficient algorithm than GNFS. However, it is also good to protect against potential future improvements over GNFS, so 3072 or 4096 bit RSA is still probably a good idea.

Re: Bruce Schneier has changed his PGP key to 4096 bits

#36

Post by SwellJoe » Thu, Sep 12, 2013, 10:49 PM UTC

vabmit wrote: post #22

mrjj wrote: post #13

Is he really afraid of 2^n/2 brute power of quantum computers or this is just overkilling of overkill?

There's no need for a quantum computer. Everyone should be using at least 4096bit RSA. 1024bit RSA keys can be factored with conventional non-specialized hardware (read: CPU's, not even GPU's) with GNFS. IMHO, 2048bit RSA keys can be factored by custom hardware that the NSA has developed. I posted my reasoning for this hypothesis in other hackernews threads. A very quick/terse run down of the main key points - 1) NSA…

"2. Al Qaeda uses 2048bit RSA for internal communications

3. Most corps, diplomats, criminals, and normal people use 2048bit RSA either directly (SSH keys, Website Certs, VPNs) or indirectly (CA's still use 2048bit RSA certs valid until 2020)"

I don't see how this is evidence that NSA has the ability to compromise 2048 bit keys, at will. Only that they very likely desire that ability. Math doesn't respond to desire.

That's not to say I believe they don't. Just that I can't accept two of your three premises for why one should believe they do.

Re: Bruce Schneier has changed his PGP key to 4096 bits

#37

Post by steveklabnik » Thu, Sep 12, 2013, 10:51 PM UTC

tomrod wrote: post #26

I know I'm still a cryptographic neophyte, but why doesn't he use four times the bits?

Sometimes longer keys are worse. I am also a newbie so I forget what that kind of attack is called.

Re: Bruce Schneier has changed his PGP key to 4096 bits

#38

Post by bdesimone » Thu, Sep 12, 2013, 10:54 PM UTC

tptacek wrote: post #9

Or: - he really doesn't use his PGP key all that often, had the same one for 16 years on god knows how many computers, and decided that if he's going to generate a new one, he might as well send a message with it.

I'm not sure this is so much an "or", but maybe, at best, an "and" given the circumstances of source material he is currently working with. I'm not as ready to assume the timing is only routine maintenance.

Re: Bruce Schneier has changed his PGP key to 4096 bits

#39

Post by betterunix » Thu, Sep 12, 2013, 10:55 PM UTC

miloshadzic wrote: post #32

tptacek wrote: post #18

Earlier quoted context omitted.

Most people don't use PGP on a regular basis. I'm use PGP a lot, more than I think most HN readers, but most of the people I talk to (even in my own field, which is full of secrets and adversaries) don't have PGP keys.

Does the reason for that ever come up in a conversation? I thought that everyone working in security used PGP a lot.

In fact, it is unusual to see people even sign emails in the (academic) cryptography community, let alone encrypt messages (at least in my experience). It is surprisingly rare to see academic crypto researchers actually use the systems they design, even for basic things like signing and encryption.

Re: Bruce Schneier has changed his PGP key to 4096 bits

#40

Post by tptacek » Thu, Sep 12, 2013, 10:57 PM UTC

bdesimone wrote: post #38

tptacek wrote: post #9

Or: - he really doesn't use his PGP key all that often, had the same one for 16 years on god knows how many computers, and decided that if he's going to generate a new one, he might as well send a message with it.

I'm not sure this is so much an "or", but maybe, at best, an "and" given the circumstances of source material he is currently working with. I'm not as ready to assume the timing is only routine maintenance.

Who says it has to be "routine" maintenance? It's obviously not; he's changing his key after 16 years. What's more likely is that he's just much more aware of his PGP key now than he was in the preceding years, because of the prominence he's taken in the story and the fact that he's now actively courting leakers.