Re: [Cryptography] prism proof email, namespaces, and anonymity
John Kelsey writes: > In the overwhelming majority of cases, I know and want to know the > people I'm talking with. I just don't want to contents of those > conversations or the names of people I'm talking with to be revealed > to eavesdroppers. And if I get an email from one of my regular > correspondents, I'd like to know it came from him, rather than being > spoofed from someone else. That's a good description of stealthmail [1]. My only regret is that it badly needs an update and I don't have time these days to work on it. But it still works out of the box. Here's the Debian description: Package: stealthmail Architecture: all Pre-Depends: gnupg Depends: procmail, esubbf, openssl, dc, libssl0.9.6 | libssl0.9.7, fetchmail | kmail, suck, ppp, solid-pop3d, exim | exim4, dpkg (>= 1.10.21), grep (>= 2.5), bash (>= 2.05b), ${shlibs:Depends}, ${misc:Depends} Description: scripts to hide whether you're doing email, or when, or with whom Maintain on-going random cover traffic via usenet newsgroup alt.anonymous.messages, substituting encrypted live traffic when available. A live message is indistinguishable from a random cover message except with the decryption keys. All potential participants send messages to alt.anonymous.messages with rigid periodicity uncorrelated with any live traffic, and maintain an uninterrupted full feed from alt.anonymous.messages, so that an observer cannot determine whether, when, or among whom live communication is happening. . Members of a "stealthmail group" -- call it "OurGroup" for purposes of this discussion -- are defined by their knowledge of the encryption keys created for the group. With this package installed, mail addressed to OurGroup@stealthmail does not go directly to the Internet like ordinary mail, but gets encrypted by the OurGroup key, given an encrypted subject intelligible only with OurGroup keys, and queued to go to alt.anonymous.messages in place of a piece of cover traffic at the next scheduled sending time. Meanwhile, all messages appearing on alt.anonymous.messages are downloaded into an incoming queue. A POP3 server runs on the local host. The mail reader is provided with filters so that when it fetches mail from this local server, messages having subject lines encrypted for OurGroup (or any other stealthmail group of which this host is a member) are decrypted by the appropriate key and presented. Other messages are discarded. [1] See mailto URL below. -- -- StealthMonger Long, random latency is part of the price of Internet anonymity. anonget: Is this anonymous browsing, or what? http://groups.google.ws/group/alt.privacy.anon-server/msg/073f34abb668df33?dmode=source&output=gplain stealthmail: Hide whether you're doing email, or when, or with whom. mailto:stealthsu...@nym.mixmin.net?subject=send%20index.html Key: mailto:stealthsu...@nym.mixmin.net?subject=send%20stealthmonger-key pgpqkHhnE3m__.pgp Description: PGP signature ___ The cryptography mailing list cryptography@metzdowd.com http://www.metzdowd.com/mailman/listinfo/cryptography
Re: [Cryptography] prism proof email, namespaces, and anonymity
On Sep 15, 2013, at 7:47 AM, Adam Back wrote: > Another design permutation I was thinking could be rather interesting is > unobservable mail. That is to say the participants know who they are > talking to (signed, non-pseudonymous) but passive observers do not. It > seems to me that in that circumstance you have more design leverage to > increase the security margin using PIR like tricks than you can with > pseudonymous/anonymous - if the "contract" is that the system remains very > secure so long as both parties to a communication channel want it to remain > that way. This seems like the main way most people would want PPE to work--like email they have now, but much more secure and resistant to abuse. In the overwhelming majority of cases, I know and want to know the people I'm talking with. I just don't want to contents of those conversations or the names of people I'm talking with to be revealed to eavesdroppers. And if I get an email from one of my regular correspondents, I'd like to know it came from him, rather than being spoofed from someone else. For most people, I'm pretty sure the security problems with email are centered around the problem of getting unwanted communication from people you don't want to hear from, some of which may manage install malware on your computer, others of which want to waste your time with scam ads, etc. A PPE scheme that solves that problem can get a lot more users than one that doesn't, and may even eventually take over from the current kind of email. > Adam --John ___ The cryptography mailing list cryptography@metzdowd.com http://www.metzdowd.com/mailman/listinfo/cryptography
Re: [Cryptography] prism proof email, namespaces, and anonymity
On Fri, Sep 13, 2013 at 04:55:05PM -0400, John Kelsey wrote: The more I think about it, the more important it seems that any anonymous email like communications system *not* include people who don't want to be part of it, and have lots of defenses to prevent its anonymous communications from becoming a nightmare for its participants. Well you could certainly allow people to opt-in to receiving anonymous email, send them a notification mail saying an anonymous email is waiting for them (and whatever warning that it could be a nastygram, as easily as the next thing). People have to bear in mind that email itself is not authenticated - SMTP forgeries still work - but there are still a large number of newbies some of whom have sufficiently thin skin to go ballistic when they realize they received something anonymous and not internalized the implication of digital free-speech. At ZKS we had a pseudonymous email system. Users had to pay for nyms (a pack of 5 paid per year) so they wouldnt throw them away on nuisance pranks too lightly. They could be blocked if credible abuse complaint were received. Another design permutation I was thinking could be rather interesting is unobservable mail. That is to say the participants know who they are talking to (signed, non-pseudonymous) but passive observers do not. It seems to me that in that circumstance you have more design leverage to increase the security margin using PIR like tricks than you can with pseudonymous/anonymous - if the "contract" is that the system remains very secure so long as both parties to a communication channel want it to remain that way. There were also a few protocols for to facilitate anonymous abuse resistant emails - user gets some kind of anonymously refreshable egress capability token. If they abuse they are not identified but lose the capability. eg http://www-users.cs.umn.edu/~hopper/faust-wpes.pdf Finally there can be different types of costs for nyms and posts - creating nyms or individual posts can cost real money (hard to retain pseudonymity), bitcoin, or hashcash, as well lost reputation if a used nym is canceled. Adam ___ The cryptography mailing list cryptography@metzdowd.com http://www.metzdowd.com/mailman/listinfo/cryptography
Re: [Cryptography] prism proof email, namespaces, and anonymity
On Fri, Sep 13, 2013 at 10:12 PM, Perry E. Metzger wrote: > On Fri, 13 Sep 2013 16:55:05 -0400 John Kelsey > wrote: > > Everyone, > > > > The more I think about it, the more important it seems that any > > anonymous email like communications system *not* include people who > > don't want to be part of it, and have lots of defenses to prevent > > its anonymous communications from becoming a nightmare for its > > participants. If the goal is to make PRISM stop working and make > > the email part of the internet go dark for spies (which definitely > > includes a lot more than just US spies!), then this system has to > > be something that lots of people will want to use. > > > > There should be multiple defenses against spam and phishing and > > other nasty things being sent in this system, with enough > > designed-in flexibility to deal with changes in attacker behavior > > over tome. > > Indeed. As I said in the message I just pointed Nico at: > http://www.metzdowd.com/pipermail/cryptography/2013-August/016874.html > > Quoting myself: > >Spam might be a terrible, terrible problem in such a network since >it could not easily be traced to a sender and thus not easily >blocked, but there's an obvious solution to that. I've been using >Jabber, Facebook and other services where all or essentially all >communications require a bi-directional decision to enable messages >for years now, and there is virtually no spam in such systems >because of it. So, require such bi-directional "friending" within >our postulated new messaging network -- authentication is handled >by the public keys of course. > The keys. This to me is the critical point for widespread adoption, key management. How do you do this in a way that doesn't put people off immediately. There are two new efforts I'm aware if trying to solve this in a user friendly way are https://parley.co/#how-it-works and http://mailpile.is. Parley's approach does at least deal with the longevity of the private key although it does boil security down to a password, if I can obtain their packet and the salt I can probably brute force the password. I've exchanged mails with the mailpile.is guys and I think they're still looking at the options. Max ___ The cryptography mailing list cryptography@metzdowd.com http://www.metzdowd.com/mailman/listinfo/cryptography
Re: [Cryptography] prism proof email, namespaces, and anonymity
On Fri, 13 Sep 2013 16:55:05 -0400 John Kelsey wrote: > Everyone, > > The more I think about it, the more important it seems that any > anonymous email like communications system *not* include people who > don't want to be part of it, and have lots of defenses to prevent > its anonymous communications from becoming a nightmare for its > participants. If the goal is to make PRISM stop working and make > the email part of the internet go dark for spies (which definitely > includes a lot more than just US spies!), then this system has to > be something that lots of people will want to use. > > There should be multiple defenses against spam and phishing and > other nasty things being sent in this system, with enough > designed-in flexibility to deal with changes in attacker behavior > over tome. Indeed. As I said in the message I just pointed Nico at: http://www.metzdowd.com/pipermail/cryptography/2013-August/016874.html Quoting myself: Spam might be a terrible, terrible problem in such a network since it could not easily be traced to a sender and thus not easily blocked, but there's an obvious solution to that. I've been using Jabber, Facebook and other services where all or essentially all communications require a bi-directional decision to enable messages for years now, and there is virtually no spam in such systems because of it. So, require such bi-directional "friending" within our postulated new messaging network -- authentication is handled by the public keys of course. > Some thoughts off the top of my head. Note that while I think all > these can be done with crypto somehow, I am not thinking of how to > do them yet, except in very general terms. > > a. You can't freely send messages to me unless you're on my > whitelist. That's my solution. As I note, it seems to work for Jabber, Facebook and other such systems, so it may be sufficient. > b. This means an additional step of sending me a request to be > added to your whitelist. This needs to be costly in something the > sender cares about--money, processing power, reputation, solving a > captcha, rate-limits to these requests, whatever. I'm not sure about that. Jabber doesn't really rate limit the number of friend requests I get per second but I don't seem to get terribly many, perhaps because fakes at most could hide some attempted phish in a user@domain name, which isn't very useful to scammers. > g. The format of messages needs to be restricted to block malware, > both the kind that wants to take over your machine and the kind > that wants to help the attacker track you down. Plain text email > only? Some richer format to allow foreign language support? My claim that I make in my three messages from August 25 is that it is probably best if we stick to existing formats so that we can re-use existing clients. My idea was that you still talk IMAP and SMTP and Jabber to a server you control (a $40 box you get at Best Buy or the like) using existing mail and chat clients, but that past your server everything runs the new protocols. In addition to the message I linked to above, see also: http://www.metzdowd.com/pipermail/cryptography/2013-August/016870.html http://www.metzdowd.com/pipermail/cryptography/2013-August/016872.html for my wider proposals. I agree this makes email delivered malware continue to be a bit of a problem, though you could only get it from your friends. Perry -- Perry E. Metzgerpe...@piermont.com ___ The cryptography mailing list cryptography@metzdowd.com http://www.metzdowd.com/mailman/listinfo/cryptography