July 2018 - cypherpunks-legacy

Re: [cryptography] MS PPTP MPPE only as secure as *single* DES (UPDATE)
by Marsh Ray 06 Jul '18

06 Jul '18

On 04/03/2012 02:29 PM, Marsh Ray wrote: > > Therefore, from any packet capture of a PPTP session which includes the > initial handshake, a brute force of the response yields the complete NT > hash with complexity 2^57. > > The NT hash is a password-equivalent, and it represents the only secret > material that goes into the MPPE encryption key derivation. > > So MS PPTP + MS-CHAPv2 + MPPE can be no better than single DES, and a > break discloses your login credentials for use with other services. An update: Moxie Marlinspike and David Hulton have improved the attack from 2^57 to 2^56. Two days ago at Defcon 20 they released open source software for parsing network captures for any MS-CHAPv2 handshakes and an online service using a Pico Computing FPGA cluster to reverse the NT hash. This allows decrypting a captured PPTP session or logging in as the user in about half a day on average. https://www.defcon.org/html/defcon-20/dc-20-speakers.html#Marlinspike https://www.cloudcracker.com/blog/2012/07/29/cracking-ms-chap-v2/ On Monday, Jacob Applebaum and I will be presenting our "vpwns: Virtual Pwned Networks" paper at Usenix FOCI '12. It discusses the limitations of off-the-shelf VPN systems when used for user anonymity and censorship resistance. PPTP is a common choice for these systems, so we'll take the opportunity to reiterate the inherent weakness in MS-CHAPv2. https://www.usenix.org/conference/foci12/vpwns-virtual-pwned-networks This is a good opportunity for everyone to make a contribution to practical crypto. Anyone that can pitch in, let's do a full-court press on lobbying for the wholesale replacement for MS-CHAPv2 and to raise awareness of the decryptability of PPTP. We could use blog posts, press articles, tweets, etc. Let's make this the week that the whole industry realizes that vendors shipping these protocols are continuing to sell crummy sub-standard single-DES crypto products which don't conform to modern security requirements. - Marsh _______________________________________________ cryptography mailing list cryptography(a)randombit.net http://lists.randombit.net/mailman/listinfo/cryptography ----- End forwarded message ----- -- Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org ______________________________________________________________ ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE

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[tahoe-dev] Instant messaging.
by Ted Rolle, Jr. 06 Jul '18

06 Jul '18

Did I read correctly? An Instant Messaging (IM) add-on to Tahoe-LAFS? SILC is all but dead. I can't even find the source code nor contact its author, Pekka Riikonen. I don't know whether there are alternatives to SILC. SILC was a really cool project. Ted _______________________________________________ tahoe-dev mailing list tahoe-dev(a)tahoe-lafs.org http://tahoe-lafs.org/cgi-bin/mailman/listinfo/tahoe-dev ----- End forwarded message ----- -- Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org ______________________________________________________________ ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE

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[tahoe-dev] Instant messaging.
by Ted Rolle, Jr. 06 Jul '18

06 Jul '18

Did I read correctly? An Instant Messaging (IM) add-on to Tahoe-LAFS? SILC is all but dead. I can't even find the source code nor contact its author, Pekka Riikonen. I don't know whether there are alternatives to SILC. SILC was a really cool project. Ted _______________________________________________ tahoe-dev mailing list tahoe-dev(a)tahoe-lafs.org http://tahoe-lafs.org/cgi-bin/mailman/listinfo/tahoe-dev ----- End forwarded message ----- -- Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org ______________________________________________________________ ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE

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Re: [liberationtech] Why Skype (real-time) is losing out to WeChat (async)
by Eric S Johnson 06 Jul '18

06 Jul '18

> in India with the Tibetan community there, I have seen Skype, on mobiles > at least, almost thoroughly replaced by WeChat, a WhatsApp/Kakao clone > made by TenCent, the same Chinese company who created QQ. To my personal > horror, we have gone from a somewhat secure Skype with a questionable > backdoor policy, to a non-https, China-hosted service who is a known > collaborator with the Chinese government. I do a lot of cybersec trainings for activists. I take a lot of flak from crypto specialists for not deterring people from using Skype. My response isn't "Skype is safe"; it's, "show me the beef." We don't need to get into the "is Skype safe?" conversation here (we all agree that we are less able to prove its safety than we are OTR's, and Microsoft has a record of cooperating with (at least US) LEAs); my point is, I find we're only successful getting folks to change their habits when we can provide evidence (which they believe) that their old habit's unsafe. I haven't been able to do that with Skype, because Skype's insecurity is basically theoretical (for developing-worlds' activists' use cases). But the circumstantial evidence demonstrating WeChat's insecurity is much stronger ... viz. this super piece by John Kennedy: http://www.scmp.com/comment/blogs/article/1083025/hu-jia-explains-why-mobile -apps-make-activism-spooky Nathan, you've doubtless seen this article. What do your Tibetan friends say about this? "We don't care if they're monitoring our WeChat use--we're out of their reach?" ... or "what's good enough for Hu Jia is good enough for us" ... or "WeChat's convenience advantages outweigh its known security" (i.e. security isn't a sine qua non for them) ... Best, Eric -- Unsubscribe, change to digest, or change password at: https://mailman.stanford.edu/mailman/listinfo/liberationtech ----- End forwarded message ----- -- Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org ______________________________________________________________ ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE

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