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I'm giving up on PGP

blog.filippo.io

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Re: I'm giving up on PGP

#261

Post by cortesoft »

ihnorton wrote: post #169
PuffinBlue wrote: post #163

Earlier quoted context omitted.

If a video chat with public keys is secure enough to exchange a one time pad, why would you need to bother with the one time pad at all? By transmitting your OTP it is no stronger than the method used to protect it in transport, so if that transport method is secure enough to guarantee the security of the OTP, why not simply use that method for everything and forget about the OTP?

I did say "exchange secrets" for a reason -- that secret may be a key for later use (e.g. for data dumps), or actual information. What I'm trying to understand is whether the (relatively new) feasibility of interactive video channels allows for building roughly the same level of trust as would be provided by in-person key exchange. I'm basing this on the understanding, possibly incorrect, that encryption with a publi…

You are forgetting a key part of the 'trust' thing; you have no way of knowing if someone is man in the middle attacking your video chat.

Example: Alice wants to video chat with Bob to exchange the secret key and verify identity. Mallory sets up a MITM attack, and gives her own public key to both Alice and Bob. Alice and Bob think they are securely talking with each other, but they are actually securely talking with Mal, who decrypts the video, watches it, then forwards it on to the other person.

This is why you can't have a secure communication channel without trust; you don't know if your secure communication is being intercepted, read, and then passed on.

Re: I'm giving up on PGP

#262

Post by DigitalJack »

caf wrote: post #241
DigitalJack wrote: post #219

Earlier quoted context omitted.

I hate color coding. I'm in the 8-12% of men that have red-green deficient vision. You can use 10% as a rule of thumb. If I'm not mistaken in my probability math, that means in a group of 5 men, there is a 50% chance one of them is "color blind." Yet the world insists on using red/green as bad/good indicators. Drives me nuts.

You are mistaken. If probability of each of the 5 men being colorblind is independent (so eg. they're not related etc), then there's a 41% chance that at least one of them is (1 - 0.9⁵). (There's a 33% chance that exactly one of them is: 0.1 × 0.9⁴ × ⁵C₁).

Thanks. It's been too long since I've studied statistics. Might be time to watch some khan academy.

Oh, I see. Assuming probability that a man is not colorblind is 0.9, then you found the probability of none of them being colorblind and subtracted that amount from 1 to find the other side.

For anyone reading this that was bothered by my use of a specific gender, it's because colorblindness occurrence is significantly higher in men than women.

Re: I'm giving up on PGP

#263

Post by IncRnd »

ihnorton wrote: post #200
IncRnd wrote: post #184

Earlier quoted context omitted.

A video chat is not enough to safeguard secrets to be used in the future. For one, if the video chat is secure enough for an otp exchange, the otp isn't needed. Secondly, if your video chat gets recorded, which may very well happen, you need to use ephemeral keys. Thirdly, since the video chat is likely recorded, at least the meta information, the effective security of your otp degrades over time, as new breaks or sp…

Interesting, thanks. Am I understanding correctly that point 2 & most of point 3 are risks because of the possibility of either future device compromise, or e.g. quantum decryption technology? These are very general risks, so why do they apply here any more than elsewhere? I realized I probably should not have replied to the part about OTPs specifically. What I'm curious about is remote trust verification via secure…

Partially, it's not just future device compromise but also Internet recording. It is best to assume that any communication over the Internet is recorded. From that standpoint, once the keys (not the device) are cracked the internal secret is also disclosed. This was why I recommended ephemeral keys.

By "cracking the keys" a cryptographic break is not always required. It can also happen via disclosure, a weak implementation, problems with the protocol, etc. One can scan a list of recent vulnerabilities for this: session reuse, master secret reuse, session resumption, heartbleed, etc.

I would call these out in particular here, because secrets are being exchanged. If those inner secrets are used to protect (directly or indirectly) multiple messages, the key disclosure becomes more pronounced.

You are quite correct regarding quantum computing. QC is guaranteed to break elliptic curve, DH, or RSA for example. The determining factor is the number of q-bits.

What do you mean by remote trust verification via secure video. That sounds quite interesting. Do you mean facial recognition inside a channel assumed to be secure, as a secondary validation of an otherwise "pre-trusted" party?

Re: I'm giving up on PGP

#264

Post by lmm »

mjevans wrote: post #175
lmm wrote: post #153

Earlier quoted context omitted.

> eg he was saying you can't share a key across multiple devices. Or if you do, you just increase your attack vector and your weakest link becomes the hotel wifi you plug into. So what are the options here? You can have a GPG key protected by any mechanism you care to think of (passphrase, smartcard, ...). You can share it between devices or not as you see fit, subject to the same tradeoff that is always going to be…

Actually you also have to use it to sign /other people's/ keys.

True. But the point is you don't need to take it travelling with you.

Re: I'm giving up on PGP

#265

Post by pfooti »

j-conn wrote: post #115
ritonlajoie wrote: post #66

On a related thought, using a 'secure' (or so they say ?) email provider à là protonmail is just secure if you send your email to another protonmail user. Problem with services like that is they omit to tell their users that email is not E2E, and sending from protonmail to gmail will just disable the benefits of using protonmail. So yes, if you are trying to send encrypted email to a GMAIL user, your only way is to u…

When sending to a non-protonmail account, you have the option to encrypt the message contents-- recipient has to open a link and enter the password. I think decryption is done in the browser in that case too (not 100% sure tho)

That is correct. The recipient can reply from that webpage as well, however you can't have a conversation there (your replies to their replies don't show up in that page, they have to get new URLs in their email).

Re: I'm giving up on PGP

#266

Post by dpark »

5ilv3r wrote: post #183
sickbeard wrote: post #156

Earlier quoted context omitted.

In otherwords, it only works in controlled environments, not out in the wild

Not to be glib, but this is true in much the same way as secure http. Really the only way to do it properly is to control the root key for your organization. The chain of trust starting with the vendor you got the computer from is bonkers.

It's pretty bonkers that you trust a computer vendor to control the firmware on your PC but not the CA chain. If Dell is determined to listen to your conversations, they can spy from the hardware, keylog beneath the OS, or literally listen through an embedded microphone.

Re: I'm giving up on PGP

#267

Post by softawre »

jballanc wrote: post #258
caf wrote: post #241

Earlier quoted context omitted.

You are mistaken. If probability of each of the 5 men being colorblind is independent (so eg. they're not related etc), then there's a 41% chance that at least one of them is (1 - 0.9⁵). (There's a 33% chance that exactly one of them is: 0.1 × 0.9⁴ × ⁵C₁).

I think a Poison distribution would be more appropriate here, so the probability of 1 man in 5 being colorblind, assuming 10% of the population on average is colorblind, is: e^-0.5*sum((i)->(0.5^i/factorial(i)), 1:5) = ~39%

> Poison distribution

Why? This is basic statistics (% of population).

Re: I'm giving up on PGP

#268

Post by dmoy »

eropple wrote: post #227
marssaxman wrote: post #218

Earlier quoted context omitted.

Why the fuck would you ever insert a government-provided USB key into any computer you actually cared about, much less actually use any government-provided key? The national government is the prime adversary . I mean, seriously, Alice and Bob want to communicate, and your solution is that they should use Eve as a courier!??

FWIW: your point--and it's a good one--is better made without the yelling. And to answer you, though I don't speak for the person you were relying to: the U.S. government isn't even in my threat model. If the Eye of Sauron points my way, I lose. And so, given that as a prior, a universally trustable third party is not a bad idea. The implementation might totally suck (and I think it's a better practice to have a wide…

James Mickens has an awesome point roughly along these lines. It is one of my all time favorite lines about security up there with some Gene Spafford stuff.

""" If your adversary is the Mossad, YOU'RE GONNA DIE AND THERE'S NOTHING THAT YOU CAN DO ABOUT IT. The Mossad is not intimidated by the fact that you employ https://. If the Mossad wants your data, they're going to use a drone to replace your cellphone with a piece of uranium that's shaped like a cellphone, and when you die of tumors filled with tumors, they're going to hold a press conference and say "It wasn't us" as they wear t-shirts that say "IT WAS DEFINITELY US," and then they're going to buy all of your stuff at your estate sale so that they can directly look at the photos of your vacation instead of reading your insipid emails about them. """

Re: I'm giving up on PGP

#269

Post by marssaxman »

eropple wrote: post #227
marssaxman wrote: post #218

Earlier quoted context omitted.

Why the fuck would you ever insert a government-provided USB key into any computer you actually cared about, much less actually use any government-provided key? The national government is the prime adversary . I mean, seriously, Alice and Bob want to communicate, and your solution is that they should use Eve as a courier!??

FWIW: your point--and it's a good one--is better made without the yelling. And to answer you, though I don't speak for the person you were relying to: the U.S. government isn't even in my threat model. If the Eye of Sauron points my way, I lose. And so, given that as a prior, a universally trustable third party is not a bad idea. The implementation might totally suck (and I think it's a better practice to have a wide…

I take your point - though I was not intending to yell, but to represent my state of alarm and bafflement, as the original poster's worldview is both alien and frightening. It's as though someone were circulating one of those "modest proposals" to improve automobile security by installing a sharp metal spike on the center of every steering wheel, without realizing that these things are supposed to be jokes.

A universally trustable third party key provider might not be a bad idea in itself, but a national government - any national government, I was not specifically referring to the US government - seems about as non-trustworthy as any third party gets. To my way of thinking, the whole point of cryptography is to allow the weak to protect themselves from the powerful, and giving the organization which is at least nominally the most powerful agent operating in one's area the opportunity to poison your crypto before you even begin seems... counterproductive.

Re: I'm giving up on PGP

#270

Post by heartbreak »

milge wrote: post #60
heartbreak wrote: post #58

Earlier quoted context omitted.

iMessage end-to-end encryption is not a recent introduction. It has been in place for several years, though I can't find the exact iOS version it was introduced in.

Recent to me is the last few years, technology-wise. Your timeline may look different.

Fair point. We are talking about a 5 year old product though...
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