The latest auto update to Enigmail, the essential plugin for Thunderbird for encrypted mail, is a fairly dynamic project that occasionally makes UI and usability decisions that not everyone agrees with.
Why? OK – PGP/MIME leaks less metainformation than inline PGP, but at the expense of compatibility. K9 should support PGP/MIME, but it doesn’t. Enigmail should have synchronized with K9 and released PGP/MIME when mobile users could use it.
But encryption people often insist that the only use case that matters is some edge case they think is critical. They like to say that nobody should read encrypted mail on a mobile device because the baseband of the device is intrinsically insecure (all cell phones are intrinsically insecure – phones should treat the data radio as a serial modem and the OS and the data modem should interact only over a very simple command set – indeed, the radio should be a replaceable module, but that gets beyond this particular issue).
For now, make sure your default encoding is Inline-PGP or you’ll break encryption. Encryption only works if it is easy to use and universally available. When people can’t read their messages, they just stop using it. This isn’t security, this is a mistake.
Whisper systems wrote the very useful TextSecure app for Android. It had a great feature of encrypting text messages, a standard communication modality in much of the world and one I rely on often. I have previously suggested it is a good tool.
The last “update” removed the ability to establish new encrypted chats over SMS and, it appears, the next will remove the function entirely. For me, this change substantially reduces the utility of the app.
Reading their arguments for doing so, I find myself disagreeing with their justifications. I understand there was some complexity in establishing encrypted SMS, but frankly initiating a one-time key exchange was about as easy as encrypted communication gets. That iOS users can’t play along is pretty irrelevant: iOS isn’t exactly the platform for secure communications anyway, you carry iOS devices when you want to impress people with your brand awareness, not get things done. That people occasionally end up with a conversation that is half-encrypted seems annoying but hardly all that problematic. The person that uninstalled the app will try to send messages in the clear, not the person who is still running it and a partial session. I can see the annoyance, but not any security leak.
I think the final result is somewhat dangerous. The first incarnation used SMS as the starting point, and once a secure communications were established, if available, coms moved transparently to the data channel. If not, it stayed with SMS. As I work in a place where data service is frequently disabled, this was the most reliable non-voice communication protocol.
Now SMS is unencrypted and data-mode communication is encrypted. You have to remember which is which and that is dangerous.
If they don’t restore encrypted SMS functionality, I will switch back to the standard SMS app, which is insecure SMS only and so not confusing and use chat secure or xabber for encrypted data communications so the difference is clear. You’re probably going to run a jabber-based chat tool anyway chat secure’s Tor integration makes it a better choice for data-mode chat while text secure no longer does anything particularly useful over the default app for SMS-mode nor anything particularly unique for data mode.
Some of the summaries of the Sony attacks are a little despairing of the viability of internet security, for example Schneier:
This could be any of us. We have no choice but to entrust companies with our intimate conversations: on email, on Facebook, by text and so on. We have no choice but to entrust the retailers that we use with our financial details. And we have little choice but to use butt services such as iButt and Google Docs.
I respectfully disagree with some of the nihilism here: you do not need to put your data in the butt. Butt services are “free,” but only because you’re the product. If you think you have nothing to hide and privacy is dead and irrelevant, you are both failing to keep up with the news and extremely unimaginative. You think you have no enemies? Nobody would do you wrong for the lulz? Nobody who would exploit information leaks for social engineering to rip you off?
Use butt services only when the function the service provides is predicated on a network effect (like Facebook) or simply can’t be replicated with individual scale resources (Google Search). Individuals can reduce the risk of being a collateral target by setting up their own services like an email server, web server, chat server, file server, drop-box style server, etc. on their own hardware with minimal expertise (and the internet is actually full of really good and expert help if you make an honest attempt to try), or use a local ISP instead of relying on a global giant that is a global target.
Email Can be Both Secure AND Convenient:
But there’s something this Sony attack has made even more plain: eMail security is bad. Not every company uses the least insecure email system possible and basically invites hackers to a data smorgasborg like Sony did by using outlook (I mean seriously, they can’t afford an IT guy who’s expertise extends beyond point-n-click? Though frankly the most disappointing deployment of outlook is by MIT’s IT staff. WTF?).
As lame as that is, email systems in general suffer from an easily remediated flaw: email is stored on the server in plain text which means that as soon as someone gets access to the email server, which is by necessity of function always globally network accessible, all historical mail is there for the taking.
Companies institute deletion policies where exposed correspondence is minimized by auto-deleting mail after a relatively short period, typically about as short as possible while still, more or less, enabling people to do their jobs. This forced amnesia is a somewhat pathetic and destructive solution to what is otherwise an excellent historical resource: it is as useful to the employees as to hackers to have access to historical records and forced deletion is no more than self-mutilation to become a less attractive target.
It is trivial to create a much more secure environment with no meaningful loss of utility with just a few simple steps.
Proposal to Encrypt eMail at Rest:
I wrote in detail about this recently. I realize it is a TLDR article, but as everyone’s wound up about Sony, a summary might serve as a lead-in for the more actively procrastinating. With a few very simple fixes to email clients (which could be implemented with a plug-in) and to email servers (which can be implemented via mail scripting like procmail or amavis), email servers can be genuinely secure against data theft. These fixes don’t exist yet, but the two critical but trivial changes are:
Step One: Server Fix
- Your mail server will have your public key on it (which is not a security risk) and use it to encrypt every message before delivering it to your mailbox if it didn’t come in already encrypted.
This means all the mail on the sever is encrypted as soon as it arrives and if someone hacks in, the store of messages is unreadable. Maybe a clever hacker can install a program to exfiltrate incoming messages before they get encrypted, but doing this without being detected is very difficult and time consuming. Grabbing an .ost file off some lame Windows server is trivial. I don’t mean to engage in victim blaming, but seriously, if you don’t want to get hacked, don’t go out wearing Microsoft.
Encrypting all mail on arrival is great security, but it also means that your inbox is encrypted and as current email clients decrypt your mail for viewing, but then “forget” the decrypted contents, encrypted messages are slower to view than unencrypted ones and, most crippling of all, you can’t search your encrypted mail. This makes encrypted mail unusable, which is why nobody uses it after decades. This unusability is a tragic and pointless design flaw that originated to mitigate what was then, apparently, a sore spot with one of Phil’s friends who’s wife had read his correspondence with another woman and divorce ensued; protecting the contents of email from client-side snooping has ever since been perceived as critical.1I remember this anecdote from an early 1990’s version of PGP. I may be mis-remembering it as the closest reference I can find is this FAQ:
It was a well-intentioned design constraint and has become a core canon of the GPG community, but is wrong-headed on multiple counts:
- An intimate partner is unlikely to need the contents of the messages to reach sufficient confidence in distrust: the presence of encrypted messages from a suspected paramour would be more than sufficient cause for a confrontation.
- It breaks far more frequent use such as business correspondence where operational efficiency is entirely predicated on content search which doesn’t work when the contents are encrypted.
- Most email compromises happen at the server, not at the client.
- Everyone seems to trust butt companies to keep their affairs private, much to the never-ending lulz of such companies.
- Substantive classes of client compromises, particularly targeted ones, capture keystrokes from the client, meaning if the legitimate user has access to the content of the messages, so too does the hacker, so the inconvenience of locally encrypted mail stores gains almost nothing.
- Server attacks are invisible to most users and most users can’t do anything about them. Users, like Sony’s employees, are passive victims of sysadmin failures. Client security failures are the user’s own damn fault and the user can do something about them like encrypting the local storage of their device which protects their email and all their other sensitive and critical selfies, sexts, purchase records, and business correspondence at the same time.
- If you’re personally targeted at the client side, that some of your messages are encrypted provides very little additional security: the attacker will merely force you to reveal the keys.
Step Two: Client Fix
- Your mail clients will decrypt your mail automatically and create local stores of unencrypted messages on your local devices.
If you’ve used GPG, you probably can’t access any mail you got more than a few days ago; it is dead to you because it is encrypted. I’ve said before this makes it as useless as an ephemeral key encrypted chat but without the security of an ephemeral key in the event somebody is willing to force you to reveal your key and is interested enough to go through your encrypted data looking for something. They’ll get it if they want it that bad, but you won’t be bothered.
But by storing mail decrypted locally and by decrypting mail as it is downloaded from the server, the user gets the benefit of “end-to-end encryption” without any of the hassles.
GPG-encrypted mail would work a lot more like an OTR encrypted chat. You don’t get a message from OTR that reads “This chat message is encrypted, do you want to decrypt it? Enter your password” every time you get a new chat, nor does the thread get re-encrypted as soon as you type something, requiring you to reenter your key to review any previous chat message. That’d be idiotic. But that’s what email does now.
These two simple changes would mean that server-side mail stores are secure, but just as easy to use and as accessible to clients as they are now. Your local device security, as it is now, would be up to you. You should encrypt your hard disk and use strong passwords because sooner or later your personal device will be lost or stolen and you don’t want all that stuff published all over the internet, whether it comes from your mail folder or your DCIM folder.
It doesn’t solve a targeted attack against your local device, but you’ll always be vulnerable to that and pretending that storing your encrypted email on your encrypted device in an encrypted form adds security is false security that has the unfortunate side effect of reducing usability and thus retarding adoption of real security.
If we did this, all of our email will be encrypted, which means there’s no additional hassle to getting mail that was encrypted with your GPG key by the sender (rather than on the server). The way it works now, GPG is annoying enough to warrant asking people not to send encrypted mail unless they have to, which tags that mail as worth encrypting to anyone who cares. By eliminating the disincentive, universally end-to-end encrypted email would become possible.
A few other minor enhancements that would help to really make end-to-end, universally encrypted email the norm include:
- Update mail clients to prompt for key generation along with any new account (the only required option would be a password, which should be different from the server-log-in password since a hash of that has to be on the server and a hash crack of the account password would then permit decryption of the mail there, so UX programmers take note!)
- Update address books, vcard, and LDAP servers so they expect a public key for each correspondent and complain if one isn’t provided or can’t be found. An email address without a corresponding key should be flagged as problematic.
- Corporate and hierarchical organizations should use a certificate authority-based key certification system, everyone else should use web-of-trust/perspectives style key verification, which can be easily automated to significantly reduce the risk of MitM attacks.
This is easy. It should have been done a long time ago.
Footnotes [ + ]
|1.||↑||I remember this anecdote from an early 1990’s version of PGP. I may be mis-remembering it as the closest reference I can find is this FAQ:|
One of the most horrible mistakes made in the early days of the internet was to use SSL (an “HTTPS” connection) for both securing a connection with encryption and verifying that the server you reach matches the URL you entered.
Encryption is necessary so you can’t be spied on by anyone running wireshark on the same hotspot you’re on, something that happens all the time, every day, to everyone connecting to public wifi, which means just about everyone just about any time they take a wifi device out of the house. It is pretty certain that you – you yourself – have thwarted cybercrime attempts thanks to SSL, not just once but perhaps dozens of times a day, depending on how often you go to Starbucks.
The second purpose, attempting to guarantee that the website you reached is served by the owner of the domain name as verified by some random company you’ve never heard of is an attempt to thwart so-called “Man in the Middle” (MITM) and DNS poisoning attacks. While these are also fairly easy (especially the latter), they’re both relatively uncommon and the “fix” doesn’t work anyway.
In practice, the “fix” can be detrimental because it gives a false sense of security to that sliver of the population that knows enough to be aware that the browser bar ever shows a green lock or any other indicator of browser trust and not aware enough to realize that the indicator is a lie. It is beyond idiotic that our browsers make a big show of this charade of identity verification with great colorful warnings of non-compliance whenever detected to order to force everyone to pay off the cert mafia and join in the protection racket of pretending that their sites are verified.
I’ve written before why this is counterproductive, but the basic problems is that browsers ship with a set of “root” certificates1You can review a list of the certificates of trusted Certificate Authorities here. Note that the list includes state-agency certificates from countries with controversial human rights records. that they trust for no good reason at all except that there’s a massive payola racket and if you’re a certificate issuer with a distributed accepted CA certificate you can print money by charging people absurd fees for executing a script on your server which, at zero cost to the operator, “signs” their certificate request (oh please, please great cert authority sign my request) so that browsers will accept it without warning. It isn’t like they actually have the owner of the site come in to their office, show ID, and verify they are who they say they are. Nobody does that except CACert; which is a free service and, surprise, their root cert is not included in any shipping browser.
Users then will typically “trust” that the site they’re connecting to is actually the one they expected when they typed in a URL. Except they didn’t type a URL, they clicked on a link and they really have no idea where there browser is going and will not read the URL in the browser bar anyway and bankomurica.com is just as valid as bankofamerica.com, so the typical user has no clue where the browser thinks it is going and a perfectly legit, valid cert can be presented for a confusing (or not really so much) URL. Typosquatters and pranksters have exploited this very successfully and have proven beyond any doubt that pretending that a URL is an unambiguous identifier is foolish and so too, therefore, is proving that the connection between the browser and the URL hasn’t been hijacked.
Further, law enforcement in most countries require that service providers ensure that it is possible to surreptitiously intercept communications on the web: that is do the exact thing we’re sold that a “valid” certificate makes “impossible.” In practice they get what are called “lawful intercept” certificates which are a bit like fireman’s key that doesn’t compromise your security because only a fireman would ever, ever have one.. Countries change hands and so do these. If you think you’re a state-level target and certificate signing has any value, you’re actually putting your life at risk. This is an immense disservice because there will be some people at risk, under surveillance, who will actually pay attention to the green bar and think it means they are safe. It does not. They may die. Really.
Commercial certs can cost thousands of dollars a year and they provide absolutely zero value to the site visitor except making the browser warnings go away so they can visit the site without dismissing meaningless and annoying warnings. There is absolutely no additional value to the site operator for a commercial cert over a completely free self-signed cert except to make the browser warnings go away for their visitors. The only entity that benefits from this is the certificate vendor from the fees they charge site operators and for the browser vendor for whatever fees are associated with including their certificates in the browser installer. You, the internet user, just lose out because small sites don’t use encryption because they can’t afford certs or the hassle and so your security is compromised to make other people rich.
There are far better tools2The hierarchical security model that browsers currently use, referencing a certificate authority, does work well for top-down organizations like companies or the military (oddly, the US Military’s root certificates aren’t included in browsers). In such a situation, it makes sense for a central authority to dictate what sources are trusted. It just does not make sense in an unstructured public environment where the “authority” is unknown and their vouch means nothing. that use a “Web Of Trust” model that was pioneered by PGP back in the early 1990s that actually does have some meaning and is used by CACert, meaning CACert certificates actually have some meaning when they indicate that the site you’re visiting is the one indicated by the URL, but since CACert doesn’t charge and therefore can’t afford to buy into the cert mafia, their root certs are not included in browsers, so you have to install it yourself.
The result is that a small website operator has four options:
- Give up on security and expose all the content that moves between their server and their visitors to anyone snooping or logging,
- Use a self-signed cert3If you’re running your own web services, for example a web-interface to your wifi router or a server or some other device with a web interface, it will probably use a self-signed cert and you’ve probably gotten used to clicking through the warnings, which at least diminishes the blackmail value of the browser warnings as people get used to ignoring them. Installing certificates in Firefox is pretty easy. It is a major hassle in Chrome or IE (because Chrome, awesome work Google, great job, uses IE’s certificate store, at least on Windows). Self-signed certs are used everywhere in IT management, almost all web-interfaced equipment uses them. IBM has a fairly concise description of how to install the certs. Firefox wins. to encrypt traffic that will generate all sorts of browser warnings for their visitors in an attempt to extort money from them,
- Use one of the free SSL certificate services that become increasingly annoying to keep up to date and provide absolutely zero authentication value but will encrypt traffic without generating warnings,
- Use CACert and ask users to be smart enough to install the CACert root certificate and thus actually encrypt and reasonably securely prove ownership.
Footnotes [ + ]
|1.||↑||You can review a list of the certificates of trusted Certificate Authorities here. Note that the list includes state-agency certificates from countries with controversial human rights records.|
|2.||↑||The hierarchical security model that browsers currently use, referencing a certificate authority, does work well for top-down organizations like companies or the military (oddly, the US Military’s root certificates aren’t included in browsers). In such a situation, it makes sense for a central authority to dictate what sources are trusted. It just does not make sense in an unstructured public environment where the “authority” is unknown and their vouch means nothing.|
|3.||↑||If you’re running your own web services, for example a web-interface to your wifi router or a server or some other device with a web interface, it will probably use a self-signed cert and you’ve probably gotten used to clicking through the warnings, which at least diminishes the blackmail value of the browser warnings as people get used to ignoring them. Installing certificates in Firefox is pretty easy. It is a major hassle in Chrome or IE (because Chrome, awesome work Google, great job, uses IE’s certificate store, at least on Windows). Self-signed certs are used everywhere in IT management, almost all web-interfaced equipment uses them. IBM has a fairly concise description of how to install the certs. Firefox wins.|
Occasionally you find the crankypants commentary about the “problems” with PGP. These commentaries are invariably written by people who fail to recognize the use modality that PGP is meant to address.
PGP is a cryptographic tool that is, genuinely, annoying to use in most current implementations (though I find the APG extension to the K9 mail app on the android as easy or easier to use than the current Enigmail implementation for Thunderbird.) The purpose of PGP is to encrypt the contents of mail messages sent between correspondents. Characteristics of these messages are that they have more than ephemeral value (you might need to reference them again in the future) and that the correspondents are not attempting to hide the fact that they correspond.
It is intrinsic to the capabilities of the tool that it does not serve to hide with whom you are communicating (there are tools for doing this, but they involve additional complexity) and all messages encrypted with a single key can be decrypted with that key. As such keys are typically protected by a password the user must remember. It is a sufficiently accurate simplification of the process to consider the messages themselves protected by a password that the owner of the messages must remember and might possibly be forced to divulge as the fundamental limit on the security of the messages so protected. There are different tools for different purposes that exchange ephemeral keys that the user doesn’t ever know, aren’t protected by a mnemonic password, and therefore can never be forced to divulge).
These rants against PGP annoy me because PGP is an excellent tool that is marred by minor usability problems. Energy expended on ignorantly dismissing the tool is energy that could be better spent improving it. By far the most important use cases for the vast majority of users that have any real reason to consider cryptography are only addressed by PGP. I make such a claim based on the following:
- Most business and important correspondence is conducted by email and despite the hyperventilation of some ignorant children, will remain so for the foreseeable future.
- Important correspondence, more or less by definition, has a useful shelf life of more than one read and generally serves as a durable (and legally admissible) record.
- There are people who have legitimate reasons to obfuscate their correspondents: email, even PGP encrypted email, is not a suitable tool for this task.
- There are people who have legitimate reason to communicate messages that must not be permanently recorded and for which either the value of the communication is ephemeral or the risk is so great that destroying the archive is a reasonable trade-off: email, even with PGP, is not a suitable tool for this task.
- There’s some noise in the rant about not being sufficient to protect against NSA targeted intercept or thwarting NSA data archiving, which makes an implicit claim that the author has some solution that might provide such protection to end users. I consider such claims tantamount to homicide. If someone is targeted by state-level surveillance, they can’t use a Turing-complete device (any digital device) to communicate information that puts them at risk; any suggestion to the contrary is dangerous misinformation.
Current implementations of PGP have flaws:
- For some reason, mail clients still don’t prompt for the import or generation of PGP keys whenever a new account is set up. That’s somewhat pathetic.
- For some reason, address books integrated into mail clients don’t have a field for the public key of the associate. This is a bizarre omission that necessitates add-on key management plug-ins that just make the process more complicated.
- It is somewhat complicated by IMAP, but no client stores encrypted messages locally in unencrypted form, which makes them difficult to search and reduces their value as an archival record. This has trivial security value: your storage device is, of course, encrypted or exposing your email should your device be lost is likely to be the least of your problems.
PGP is, despite these shortcomings, one of the most important cryptographic tools available.
Awesome properties of PGP keys no other cryptographic system can touch
PGP keys are (like all cryptographic keys in use by any system) long strings of seemingly random data. The more seemingly random, the better. They are, by that very nature, nonmnemonic. Public key cryptosystems, like PGP, have an awesome, incredibly useful characteristic that you can publish your public key (a long, random string of numbers) and someone you’ve never met can encrypt a message using that public key and only your private key can decrypt it.
Conversely, you can “sign” data with your “private key” and anyone can verify that you signed it by decrypting it with your public key (or more precisely a short mathematical summary of your message). This is so secure, it is a federally accepted signature mechanism.
There’s a hypothesized attack called a Man In The Middle attack (often abbreviated “MITM”) that exploits the fact these keys aren’t really human readable (you can, but they’re so long you won’t) whereby an attacker (traditionally the much maligned Eve) intercepts messages between two parties (traditionally the secretive Alice and Bob), pretending to be Bob whilst communicating with Alice and pretending to be Alice whilst communicating with Bob. By substituting her keys for Alice’s and Bob’s, both Bob and Alice inadvertently send messages that Eve can decrypt and she “simply” forwards Bob’s to Alice using Alice’s public key and vice versa so they decrypt as expected, despite coming from the evil Eve.
Eve must, however, be able to intercept all of Alice and Bob’s communication or her attack may be discovered when the keys change, which is not practical in the real world on an ongoing basis (but, ironically, is easier with ephemeral keys). Pretending to be someone famous is easier and could be more valuable as people you don’t know might send you unsolicited private correspondence intended for the famous person: the cure is widely disseminating key “fingerprints” to make the discovery of false keys very hard to prevent. And if you expect people to blindly send you high-priority information with your public key, you have an obligation to mitigate the risk of a false recipient.
Occasionally it is hypothesized that this attack compromises the utility of PGP; it is a shortcoming of all cryptographic systems that the keys are not human readable if they are even marginally secure. It is intrinsic to a public key infrastructure that the public keys must be exchanged. It is therefore axiomatic that a PKI-based cryptographic system will be predicated on mechanisms to exchange nonmnemonic key information. And hidden key exchange, as implemented by OTR or other ephemeral key systems makes MITM attacks harder to detect.
While it is true that elliptic curve PKI algorithms achieve equivalent security with shorter keys, they are still far too long to be mnemonic. One might nominally equivalence a 4k RSA key with a 0.5k elliptic curve key, a non-trivial factor of 8 reduction with some significance to algorithmic efficiency, but no practical difference in human readability. Migrating to elliptic curves is on the roadmap for PGP (with GPG 2.1, now in beta) and should be expedited.
PGP Key management is a little annoying
Actually, it isn’t so much PGP that makes this true, but rather the fact that mail clients haven’t integrated PGP into the client. That Gmail and Yahoo mail will soon be integrating PGP into their mail clients is a huge step in the right direction even if integrating encryption into a webmail client is kind of pointless since the user is already clearly utterly unconcerned with privacy at all if they’re gifting Google or Yahoo their correspondence. Why people who should know better still use Gmail is a mystery to me. When people who care about data security use a gmail address it is like passing the temperance preacher passed out drunk in the gutter. With every single message sent. Even so, this is a step in the right direction by some good people at Google.
It is tragic that Mozilla has back-burnered Thunderbird, but on the plus side they don’t screw up the interface with pointless changes to justify otherwise irrelevant UX designers as does every idiotic change in Firefox with each release. Hopefully the remaining community will rally around full integration of PGP following the astonishingly ironic lead of the privacy exploiting industry.
If keys were integrated into address books in every client and every corporate LDAP server, it would go a long way toward solving the valid annoyances with PGP key management; however, in my experience key management is never the sticking point, it is either key generation or the hassle of trying to deal with data rendered opaque and nearly useless by residual encryption of the data once it has reached me.
Forward Secrecy has a place. It isn’t email.
A complaint levied against PGP that proves beyond any doubt that the complainant doesn’t understand the use case of PGP is that it doesn’t incorporate forward secrecy. Forward secrecy is a consequence of a cryptosystem that negotiates a new key for each message thread which is not shared with the users and which the system doesn’t store. By doing this, the correspondents cannot be forced to reveal the keys to decrypt the contents of stored or captured messages since they don’t know them. Which also means they can’t access the contents of their stored messages because they’re encrypted with keys they don’t know. You can’t read your own messages. There are messaging modalities where such a “feature” isn’t crippling, but email isn’t one of them; sexting perhaps, but not email.
Indeed, the biggest, most annoying, most discouraging problem with PGP is that clients do not insert the unencrypted message into the local message store after decrypting it. This forces the user to decrypt the message again each time they need to reference it, if they can ever find it again. One of the problems with this is you can’t search encrypted messages without decrypting them. No open source client I’m aware of has faced this debilitating failure of use awareness, though Symantec’s PGP desktop does (so it is solvable). Being naive about message use wouldn’t have been surprising for the first few months of GPG’s general use, but that this failure persists after decades is somewhat shocking and frustrating. It is my belief that the geekiness of most PGP interfaces has so limited use that most people (myself included) aren’t crippled by not being able to find PGP encrypted mail because we get so little of it. If even a small percentage of our mail was encrypted, not ever being able to find it again would be a disaster and we’d stop using encryption.
This is really annoying because messages have the frequently intolerable drawbacks of being ephemeral without the cryptographic value of forward secrecy.
Email is normally used as a messaging modality of record. It is the way in which we exchange contemplative comments and data that exceeds a sentence or so. This capability remains important to almost all collaborative efforts. The record thus created has archival value and is a fundamental requirement in many environments. Maximizing the availability, searchability, and ease of recall of this archive is essential. Indeed, even short form communication (“chat” in various forms), which is typically amenable to forward secrecy because of the generally low content value thus communicated, should have the option of PGP encryption instead of just OTR in order to create a secure but archival communications channel.
A modest proposal
I’ve been using PGP since the mid 1990s. I have a key from early correspondence on PGP from 1997 and mine is from 1998. Yet while I have about 2,967 contacts in my address book I have only 139 keys in my GPG keyring. An adoption rate of 4.7% for encrypted email isn’t exactly a wild success. I don’t think the problems are challenging and while I very much appreciate the emergence of cryptographically secure communications modalities such as OTR for chat and ZRTP for voice, I’ve been waiting for decades for easy-to-use secure email. And yet, when people ask me to help them set up encrypted email, I generally tell them it is complicated, I’m willing to help them out, but they probably won’t end up using it. Over the years, a few relatively easy to fix issues have retarded even my own use:
- The fact that users have to find and install a somewhat complex plugin to handle encryption is daunting to the vast majority of users. Enigmail is complicated enough that it is unusable without in-person walk-through support for most users. Even phone support doesn’t get most people through setup. Basic GPG key generation and management should be built into the mail client. Every time one sets up a new account, you should have to opt out of setting up a public key and there’s no reason for any options by default other than entering a password to protect the private key.
- Key fields should be built into the address book of every mail client by default. Any mail client that doesn’t support a public key field should be shamed and ridiculed. That’s all of them until Gmail releases end-to-end as a default feature, though that may never happen as that breaks Google’s advertising model. Remember, Google pays all their developers and buys them all lunch solely by selling your private data to advertisers. That is their entire business model. They do not consider this “evil,” but you might.
- I have no idea why my received encrypted mail is stored encrypted on my encrypted hard disk along with hundreds of thousands of unencrypted messages and tens of thousands of unencrypted documents. Like any sensible person who takes a digital device out of the house (or leaves it unprotected in the house), I encrypt my local storage to protect those messages and documents from theft and exploitation. My encrypted email messages are merely data cruft I can’t make much use of since I can’t search for them. That’s idiotic and cripples the most important use modality of email: the persistent record. Any mail client should permanently decrypt the local message store unless the user specifically requests a message be stored encrypted, an option that should be the same for a message that arrived encrypted or unencrypted.
- Once we solve the client storage failure and make encrypted email useful for something other than sending attachments (which you can save, ZOMG, in unencrypted form) and feeling clever for having gotten the magic decoder ring to work, then it would make sense to modify mail servers to encrypt all unencrypted incoming mail with the user’s public key, which mitigates a huge risk in having a mail server accessible on the internet: that the historical store of data there contained is remotely compromised. This protects data at rest (data which is often, but not assuredly, already protected in transit by encrypted transport protocols.) End-to-End encryption using shared public keys is still optimal, but leaving the mail store unencrypted at rest is an easily solved security failure and in protection in transit is largely solved (and would be quickly if gmail bounced any SMTP connection not protected by TLS 1.2+.)
Fixing the obvious usability flaws in encrypted email are fairly easy. Public key cryptography in the form of PGP/GPG is an incredibly powerful and tremendously useful tool that has been hindered in uptake by limitations of perception and by overly stringent use cases that have created onerous limitations. Adjusting the use model to match requirements would make PGP far more useful and far easier to convince people to use.
Phil Zimmerman’s essay “why I wrote PGP” applies today as much as it did in 1991:
What if everyone believed that law-abiding citizens should use postcards for their mail? If a nonconformist tried to assert his privacy by using an envelope for his mail, it would draw suspicion. Perhaps the authorities would open his mail to see what he’s hiding.
It has been almost 25 years and never has the need for universally encrypted mail been more obvious. It is time to integrate PGP into all mail clients.
There are two things I always do with a new digital device, get a good screen protector and a good case. (And the biggest memory card that will fit).
The screen protector is pretty easy: I’ve used both Zagg and Armor Suit and prefer the Armor Suit, but not by much. Both work really well and I have an Armor Suit on my Motorola Razr V9x (still the best basic cell phone I’ve ever owned) that has lived in my pocket for many, many years without a scratch visible on the outer screen.
For cases I lived with an (almost iconic) yellow Defender case for my Blackberry Bold 9000 for about 5 years. It was awesome, indestructible, and fit the belt holder perfectly. Alas, it was no match for a random late night cab ride and early flight out of Dubai–can’t defend against that, can ya? Well, it lasted about 5 years, so no complaints. I contacted Otterbox to see if I could get a replacement silicone bit and they checked and only had 2 belt holsters left in stock from the entire product line. They mailed me those for free. Thanks Otterbox! (One did come in handy eventually.)
I got an iPod from United and, of course, got an Otterbox for it; one of the Commuter series. With a polycarbonate outer shell protecting the critical corners, and that backed underneath by a few mm of soft silicone, the iPod is extremely well protected. This is a well-engineered protection model, far better than just a layer of silicone.
A corner drop tends to generate very high localized pressure where the corner tries to merge with the hard surface it is being dropped on. Having the polycarbonate outer shell distributes that pressure load over the silicone underneath it resulting in a broad, gentile distribution of the impact load and minimizing the risk of localized overpressure which would crack plastic or glass.
Conversely, simple silicone sleeves without the polycarbonate layer, while adding critical padding and being fairly effective in most cases, can’t distribute the impact load nearly so effectively. This should not matter too much for a surface-to-surface drop where the impact force is distributed over the whole back or even an edge of the phone, but in a corner drop the silicone can be effectively mushed out of the way as the hard surface attempts touch delicate plastic or glass in a tragic romance.
I replaced the Blackberry with a Samsung Galaxy S3 and got a Commuter case for it. The case is very nice, not too big, but Otterbox did something very, very wrong. They rotated the polycarbonate tabs 45 degrees, covering the edges and not the corners. Why Otter, why? The case is still quite nice and it is the nicest looking and most comfortable I’ve found, but this is an odd engineering mistake. They talk about the “layers of protection” as a key selling point for their more expensive Commuter and Defender series, yet leave the most fragile corners protected by only a single layer. As protection goes, it is no better than the Impact since the corners are all that really matters.
The polycarbonate shell does serve to anchor the access flaps closed, which is an improvement over the iPod case, but this could easily have been achieved with a few well-placed polycarbonate fingers reaching around the case without making it difficult to assemble (too many fingers wrapping around the device make it impossible to snap the device into the polycarbonate shell).
Further, the textured silicone edges on the iPod case are actually really nice to hold, far more comfortable and slip-resistant than the polycarbonate edges of the S3 case (and make the iPod less likely to drop than the S3 as well). As an additional bonus, the iPod version exposes some textured silicone on the back surface making the case somewhat non-slip, while the S3 case is all polycarbonate on the back. Without some non-slip silicone on the back, the likelihood that the enclosed device will slip off a sloped surface and onto a hard floor or into a toilet or sink is much greater. While the case makes a disaster far less likely for the former eventuality, it is not waterproof.
While the Android OS just crushes iOS, and the availability of Android-specific tools and applications, particularly for security and encryption, makes it the best choice for a mobile device right now (though security, at least, is even less of a concern with a Blackberry – that’s the one thing Rim still has going for it – that and efficient use of data), Otterbox really could have done a better job with the case. Hopefully the S4 case will get it right.
It has been almost 2 years and I’ve been carrying the Otterbox-protected S3 more or less continuously since in a relatively active and somewhat unforgiving environment, not that anyone’s pocket or purse would fail to meet that definition. A few issues emerged:
- The rubber flap covering the USB port, which you need to access at least twice a day for charging, tore off very early on;
- I change SIMS a few times a month and the case doesn’t really like being taken on and off and eventually cracked in two places, but it still holds together;
- The unprotected silicone covering the corners began to deteriorate fairly quickly, as I predicted, and one corner has disintegrated completely, leaving that most fragile of impact points unprotected.
I’d probably buy another – two years is a pretty good life (but not as good as the 5 my blackberry gave me. I still miss that phone). I wish Otterbox would focus on protecting the corners, not the edges. The iPod case, far less heavily used but equally traveled shows no wear on the corners at all and provides the same protection it did two years ago. It is a better design.
The certificate system is badly broken on a couple of levels and the most recent revelation that Turktrust accidentally issued two intermediate SSL CAs which enabled the recipients to issue presumptively valid arbitrary certificates. This is just the most recent (probably the most recent, this seems to happen a lot) compromise in a disastrously flawed system including the recent Diginotar and Comodo attacks. There are 650 root CAs that can issue certs, including some CA‘s operated by governments with potentially conflicting political interests or poor human rights records and your browser probably trusts most or all completely by default.
It is useful to think about what we use SSL certs for:
- Establishing an encrypted link between our network client and a remote server to foil eavesdropping and surveillance.
- To verify that the remote server is who we believe it to be.
Encryption is by far the most important, so much more important than verification that verification is almost irrelevant, and fundamental flaws with verification in the current CA system make even trying to enforce verification almost pointless. Most users have no idea what what any of the cryptic (no pun intended) and increasingly annoying alerts warning of “unvalidated certs” mean or even what SSL is.
Google recently started rejecting self-signed certs when attempting to establish an SSL encrypted POP connection via Gmail, an idiotically counterproductive move that will only make the internet less secure by forcing individual mail servers to connect unencrypted. And this is from the company who’s cert management between their round-robin servers is a total nightmare and there’s no practical way to ever be sure if a connection has been MITMed or not as certs come randomly from any number of registrars and change constantly.
What I find most annoying is that the extraordinary protective value of SSL encrypted communication is systematically undermined by browsers like Firefox in an intrinsically useless effort to convince users to care about verification. I have never, not once, ever not clicked through SSL warnings. And even though I often access web sites from areas that are suspected of occasionally attempting to infiltrate dissident organizations with MITM attacks, I still have yet to see a legit MITM attack in the wild myself. But I do know for sure that without SSL encryption my passwords would be compromised. Encryption really matters and is really important to keeping communication secure; anything that adds friction to encryption should be rejected. Verification would be nice if it worked.
Self-signed certs and community verified certs (like CAcert.org) should be accepted without any warnings that might slow down a user at all so that all websites, even non-commercial or personal ones, have as little disincentive to adding encryption as possible. HTTPSEverywhere, damnit. Routers should be configured to block non-SSL traffic (and HTML email, but that’s another rant. Get off my lawn.)
Verification is unsolvable with SSL certs for a couple of reason, some due to the current model, some due to reasonable human behavior, some due to relatively legitimate law-enforcement concerns, but mostly because absolute remote verification is probably an intractable problem.
Even at a well run notary, human error is likely to occur. A simple typo can, because registrar certs are by default trusted globally, compromise anyone in the world. One simple mistake and everybody is at risk. Pinning does not actually reduce this risk as breaks have so far been from generally well regarded notaries, though rapid response to discovered breaches can limit the damage. Tools like Convergence, Perspectives, and CrossBear could mitigate the problem, but only if they have sufficiently few false positives that people pay attention to the warnings and are built in by default.
But even if issuance were somehow fixed with teams of on-the-ground inspectors and biometrics and colonoscopies, it wouldn’t necessarily help. Most people would happily click through to www.bankomerica.com without thinking twice. Indeed, as companies may have purchased almost every spelling variation and point them all toward their “most reasonable” domain name, it isn’t unreasonable to do so. If bankomerica.com asked for a cert in Ubeki-beki-beki-stan-stan, would they (or even should they) be denied? No – valid green bar, invalid site. Even if misdirections were non-SSL encrypted, it isn’t practical to typo-test every legit URL against every possible fake, and the vast majority of users would never notice if their usual bank site came up unencrypted one day with a DNS attack to a site not even pretending to fake a cert (in fact, studies suggest that no users would notice). This user limitation fundamentally obviates the value of certs for identifying sites. But even a typo-misdirection is assuming too much of the user – all of my phishing spam uses brand names in anchortext leading to completely random URLs, rarely even reflective of the cover story, and the volume of such spam suggests this is a perfectly viable attack. Verification attacks don’t even need to go to a vaguely similar domain let alone go to all the trouble of attacking SSL.
One would hope that dissidents or political activists in democracy challenged environments that may be subject to MITM attacks might actually pay attention to cert errors or use perspectives, convergence, or crossbear. User education should help, but in the end you can’t really solve the stupid user problem with technology. If people will send bank details to Nigeria so that a nationality abandoned astronaut can expatriate his back pay, there is no way to educate them on the difference between https://www.bankofamerica.com and http://www.bankomerica.com. The only useful path is to SSL encrypt all sites and try to verify them via a distributed trust mechanism as implemented by GPG (explicit chain of trust), Perspectives (wisdom of the masses), or Convergence (consensus of representatives); all of these seem infinitely more reliable than trusting any certificate registry, whether national or commercial and as a bonus they escape the cert mafia by obviating the need for a central authority and the overhead entailed; but this only works if these tools have more valid positives than false positives, which is currently far from the case.
Further, law enforcement makes plausible arguments for requiring invisible access to communication. Ignoring the problematic but understandable preference for push-button access without review and presuming that sufficient legal barriers are in place to ensure such capabilities protect the innocent and are only used for good, it is not rational to believe that law enforcement will elect to give up on demanding lawful intercept capabilities wherever possible. Such intercept is currently enabled by law enforcement certificates which permit authorized MITM attacks to capture encrypted data without tipping off the target of the investigation. Of course, if the US has the tool, every other country wants it too. Sooner or later, even with the best vetting, there is a regime change and control of such tools falls into nefarious hands (much like any data you entrust to a cloud service will sooner or later be sold off in an asset auction to whoever can scrape some residual value out of your data under whatever terms suit them, but that too is a different rant). Thus it is not reasonable for activists in democracy challenged environments to assume that SSL certs are a secure way to ensure their data is not being surveilled. Changing the model from intrinsic, automatic trust of authority to a web-of-trust model would substantially mitigate the risk of lawful intercept certs falling into the wrong hands, though also making such certs useless or far harder to implement.
There is no perfect answer to verification because remote authentication is Really Hard. You have to trust someone as a proxy and the current model is to trust all or most of the random, faceless, profit or nefarious motive driven certificate authorities. Where verification cannot be quickly made and is essential to security, out of band verification is the only effective mechanism such as transmitting a hash or fingerprint of the target’s cryptographic certificate via voice or postal mail or perhaps via public key cryptography.
Sadly, the effort to prop up SSL as a verification mechanism has been made at the compromise of widespread, low friction encryption. False security is being promoted at the expense of real security.
That’s just stupid.
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