The Sinking Ship of E-Mail Security • Hacker News Board

Re: The Sinking Ship of E-Mail Security

#51

Post by e12e » Mon, Jun 30, 2014, 6:51 AM UTC

From a quick look around, it looks like the best bet on asynchronous forward secrecy that doesn't rely on a (highly) trusted server (one that eg: shares a secret with every sender and receiver, kerberos-style) is something along the lines of "The Text Secure Protocol"[1].

No reason why this couldn't be bolted on top of email (send the actual message as an attachment like with pgp/mime). It would probably create a new set of metadata (requests to the recipients "half-key" service/server (locating which could be delegated to SRV records or something similar, with domain derived from the email address) -- but I'm not aware of any other schemes for generating ephemeral keys in a reasonable manner compatible with (semi)asynchronous communications.

It does seem like "true" off-line message composition wouldn't be possible (the email client (or client service) needs to go online in order to encrypt/pack up the final message. This means that drafts/messages "in transit" would be possible to recover from the senders device in the case of eg: several mails being written on a flight w/o net access, and a search/seizure before mails could be encrypted to the receiver).

All in all, this sounds like a tricky problem... Anyone know of any recent bright ideas in the field of PFS for asynchronous messaging?

[1] https://whispersystems.org/blog/asynchronous-security/

Re: The Sinking Ship of E-Mail Security

#52

Post by pbreit » Mon, Jun 30, 2014, 5:50 PM UTC

Retric wrote: post #33

MBCook wrote: post #32

Earlier quoted context omitted.

I assume he means "threats that would allow another app or actor to read your private key".

And ignores the threat of a stolen device.

Unlike most stolen PCs, a stolen phone can be locked or erased remotely.

Re: The Sinking Ship of E-Mail Security

#53

Post by freshhawk » Tue, Jul 01, 2014, 10:25 PM UTC

superuser2 wrote: post #41

freshhawk wrote: post #22

Earlier quoted context omitted.

> which is frankly the most secure device you own Really? That's not how I treat my security at all. My phone seems to clearly be the least secure computer I own. Admittedly I run all linux on my non-phone computers, but I'm not totally sure I'd agree with you even if I ran Windows or OSX. Am I that wrong?

If it's an iPhone, then yes, it is far and away the most secure device you own. Everything is encrypted all the time through an HSM which will perform decryption only if given the device PIN. The key is never in memory and any attempt to extract it from the HSM will result in its self-destruction. It is impossible to recover data from the phone without the PIN. You can only erase the device and restore from a backup.…

Ah, that makes a lot of sense. If you are discounting Apple themselves (and people using social engineering techniques to gain access to Apples backdoors) and the large list of States and Corporate actors who have access as potential attackers then you are absolutely correct.

I didn't know about keybag, that's very interesting.

Re: The Sinking Ship of E-Mail Security

#54

Post by lifeisstillgood » Tue, Jul 01, 2014, 10:31 PM UTC

e12e wrote: post #50

lifeisstillgood wrote: post #47

Earlier quoted context omitted.

Where do I read more about this - it sounds fantastic and yet I just assume "proprietary = lazily implemented and they can read my keys cos it's on their server"

There was a talk at passwords^10 (2010) about security of pins/keys in iphone/android/windows phone (IIRC). Don't recall who the speaker was, and all the links to talks/programs etc have gone to bitrot (might be possible to find on archive.org, I've yet to try that). If I remember correctly an encrypted iphone (4 I guess?) was the most secure, but with a bit of hackery one could use the device itself to bruteforce th…

Thank you - looks interesting

Re: The Sinking Ship of E-Mail Security

#55

Post by superuser2 » Tue, Jul 01, 2014, 10:55 PM UTC

freshhawk wrote: post #53

superuser2 wrote: post #41

Earlier quoted context omitted.

If it's an iPhone, then yes, it is far and away the most secure device you own. Everything is encrypted all the time through an HSM which will perform decryption only if given the device PIN. The key is never in memory and any attempt to extract it from the HSM will result in its self-destruction. It is impossible to recover data from the phone without the PIN. You can only erase the device and restore from a backup.…

Ah, that makes a lot of sense. If you are discounting Apple themselves (and people using social engineering techniques to gain access to Apples backdoors) and the large list of States and Corporate actors who have access as potential attackers then you are absolutely correct. I didn't know about keybag, that's very interesting.

Please provide evidence (other "Apple hates my freedom so they must be doing it!") of Apple having granted access to iPhones to other corporations.

Re: The Sinking Ship of E-Mail Security

#56

Post by freshhawk » Wed, Jul 02, 2014, 1:12 AM UTC

superuser2 wrote: post #55

freshhawk wrote: post #53

Earlier quoted context omitted.

Ah, that makes a lot of sense. If you are discounting Apple themselves (and people using social engineering techniques to gain access to Apples backdoors) and the large list of States and Corporate actors who have access as potential attackers then you are absolutely correct. I didn't know about keybag, that's very interesting.

Please provide evidence (other "Apple hates my freedom so they must be doing it!") of Apple having granted access to iPhones to other corporations.

Ah, I was unclear. I meant the Governmental to private intelligence contractors path, not Apple selling data to data brokers or something like that - that seems very unlikely.