Oblivious DNS

Interesting idea: …we present Oblivious DNS (ODNS), which is a new design of the DNS ecosystem that allows current DNS servers to remain unchanged and increases privacy for data in motion and at rest. In the ODNS system, both the client is modified with a local resolver, and there is a new authoritative name server for .odns. To prevent an…

Interesting idea:

…we present Oblivious DNS (ODNS), which is a new design of the DNS ecosystem that allows current DNS servers to remain unchanged and increases privacy for data in motion and at rest. In the ODNS system, both the client is modified with a local resolver, and there is a new authoritative name server for .odns. To prevent an eavesdropper from learning information, the DNS query must be encrypted; the client generates a request for www.foo.com, generates a session key k, encrypts the requested domain, and appends the TLD domain .odns, resulting in {www.foo.com}k.odns. The client forwards this, with the session key encrypted under the .odns authoritative server’s public key ({k}PK) in the “Additional Information” record of the DNS query to the recursive resolver, which then forwards it to the authoritative name server for .odns. The authoritative server decrypts the session key with his private key, and then subsequently decrypts the requested domain with the session key. The authoritative server then forwards the DNS request to the appropriate name server, acting as a recursive resolver. While the name servers see incoming DNS requests, they do not know which clients they are coming from; additionally, an eavesdropper cannot connect a client with her corresponding DNS queries.

News article.

Subverting Backdoored Encryption

This is a really interesting research result. This paper proves that two parties can create a secure communications channel using a communications system with a backdoor. It’s a theoretical result, so it doesn’t talk about how easy that channel is to create. And the assumptions on the adversary are pretty reasonable: that each party can create his own randomness, and…

This is a really interesting research result. This paper proves that two parties can create a secure communications channel using a communications system with a backdoor. It's a theoretical result, so it doesn't talk about how easy that channel is to create. And the assumptions on the adversary are pretty reasonable: that each party can create his own randomness, and that the government isn't literally eavesdropping on every single part of the network at all times.

This result reminds me a lot of the work about subliminal channels from the 1980s and 1990s, and the notions of how to build an anonymous communications system on top of an identified system. Basically, it's always possible to overlay a system around and outside any closed system.

"How to Subvert Backdoored Encryption: Security Against Adversaries that Decrypt All Ciphertexts," by Thibaut Horel and Sunoo Park and Silas Richelson and Vinod Vaikuntanathan.

Abstract: In this work, we examine the feasibility of secure and undetectable point-to-point communication in a world where governments can read all the encrypted communications of their citizens. We consider a world where the only permitted method of communication is via a government-mandated encryption scheme, instantiated with government-mandated keys. Parties cannot simply encrypt ciphertexts of some other encryption scheme, because citizens caught trying to communicate outside the government's knowledge (e.g., by encrypting strings which do not appear to be natural language plaintexts) will be arrested. The one guarantee we suppose is that the government mandates an encryption scheme which is semantically secure against outsiders: a perhaps reasonable supposition when a government might consider it advantageous to secure its people's communication against foreign entities. But then, what good is semantic security against an adversary that holds all the keys and has the power to decrypt?

We show that even in the pessimistic scenario described, citizens can communicate securely and undetectably. In our terminology, this translates to a positive statement: all semantically secure encryption schemes support subliminal communication. Informally, this means that there is a two-party protocol between Alice and Bob where the parties exchange ciphertexts of what appears to be a normal conversation even to someone who knows the secret keys and thus can read the corresponding plaintexts. And yet, at the end of the protocol, Alice will have transmitted her secret message to Bob. Our security definition requires that the adversary not be able to tell whether Alice and Bob are just having a normal conversation using the mandated encryption scheme, or they are using the mandated encryption scheme for subliminal communication.

Our topics may be thought to fall broadly within the realm of steganography: the science of hiding secret communication within innocent-looking messages, or cover objects. However, we deal with the non-standard setting of an adversarially chosen distribution of cover objects (i.e., a stronger-than-usual adversary), and we take advantage of the fact that our cover objects are ciphertexts of a semantically secure encryption scheme to bypass impossibility results which we show for broader classes of steganographic schemes. We give several constructions of subliminal communication schemes under the assumption that key exchange protocols with pseudorandom messages exist (such as Diffie-Hellman, which in fact has truly random messages). Each construction leverages the assumed semantic security of the adversarially chosen encryption scheme, in order to achieve subliminal communication.

from https://www.schneier.com/blog/

FBI Renews Push for Access to Encrypted Smartphones

The FBI and Justice Department are renewing their call for a legal mandate to gain access to smartphones during criminal investigations.

The FBI and Justice Department officials are renewing a push for a legal mandate that tech companies build tools into smartphones and other devices that would allow access to encrypted data in criminal investigations, reports the New York Times. The federal officials have been quietly meeting with security researchers who have been working on approaches to provide such “extraordinary access” to encrypted devices. Based on that research, Justice Department officials are convinced that mechanisms allowing access to the data can be engineered without intolerably weakening the devices’ security against hacking. The officials have also revived talks inside the executive branch over whether to ask Congress to enact legislation mandating the access mechanisms. The Trump White House circulated a memo last month among security and economic agencies outlining ways to think about solving the problem, officials said.

The F.B.I. has been agitating for versions of such a mandate since 2010, complaining that the spreading use of encryption is eroding investigators’ ability to carry out wiretap orders and search warrants — a problem it calls “going dark.” The issue repeatedly flared without resolution under the Obama administration, peaking in 2016, when the government tried to force Apple to help it break into the iPhone of one of the attackers in the terrorist assault in San Bernardino, Calif. Rod J. Rosenstein, the deputy attorney general, and FBI Christopher A. Wray have begun talking publicly about the “going dark” problem, though their renewed push is certain to be met with resistance.

from https://thecrimereport.org

Two New Papers on the Encryption Debate

Seems like everyone is writing about encryption and backdoors this season. "Policy Approaches to the Encryption Debate," R Street Policy Study #133, by Charles Duan, Arthur Rizer, Zach Graves and Mike Godwin. "Encryption Policy in Democratic Regimes," East West Institute. I recently blogged about the new National Academies report on the same topic. Here’s a review of the National Academies…

Seems like everyone is writing about encryption and backdoors this season.

I recently blogged about the new National Academies report on the same topic.

Here's a review of the National Academies report, and another of the East West Institute's report.

EDITED TO ADD (3/8): Commentary on the National Academies study by the EFF.

from https://www.schneier.com/blog/

Apple to Store Encryption Keys in China

Apple is bowing to pressure from the Chinese government and storing encryption keys in China. While I would prefer it if it would take a stand against China, I really can’t blame it for putting its business model ahead of its desires for customer privacy. Two more articles….

Apple is bowing to pressure from the Chinese government and storing encryption keys in China. While I would prefer it if it would take a stand against China, I really can't blame it for putting its business model ahead of its desires for customer privacy.

Two more articles.

from https://www.schneier.com/blog/

New National Academies Report on Crypto Policy

The National Academies has just published "Decrypting the Encryption Debate: A Framework for Decision Makers." It looks really good, although I have not read it yet. Not much news or analysis yet. Please post any links you find in the comments, and I will summarize them here….

The National Academies has just published "Decrypting the Encryption Debate: A Framework for Decision Makers." It looks really good, although I have not read it yet.

Not much news or analysis yet. Please post any links you find in the comments, and I will summarize them here.

from https://www.schneier.com/blog/

WhatsApp Vulnerability

A new vulnerability in WhatsApp has been discovered: …the researchers unearthed far more significant gaps in WhatsApp’s security: They say that anyone who controls WhatsApp’s servers could effortlessly insert new people into an otherwise private group, even without the permission of the administrator who ostensibly controls access to that conversation. Matthew Green has a good description: If all you want…

A new vulnerability in WhatsApp has been discovered:

...the researchers unearthed far more significant gaps in WhatsApp's security: They say that anyone who controls WhatsApp's servers could effortlessly insert new people into an otherwise private group, even without the permission of the administrator who ostensibly controls access to that conversation.

Matthew Green has a good description:

If all you want is the TL;DR, here's the headline finding: due to flaws in both Signal and WhatsApp (which I single out because I use them), it's theoretically possible for strangers to add themselves to an encrypted group chat. However, the caveat is that these attacks are extremely difficult to pull off in practice, so nobody needs to panic. But both issues are very avoidable, and tend to undermine the logic of having an end-to-end encryption protocol in the first place.

Here's the research paper.

from https://www.schneier.com/blog/

Fighting Ransomware

No More Ransom is a central repository of keys and applications for ransomware, so people can recover their data without paying. It’s not complete, of course, but is pretty good against older strains of ransomware. The site is a joint effort by Europol, the Dutch police, Kaspersky, and McAfee….

No More Ransom is a central repository of keys and applications for ransomware, so people can recover their data without paying. It's not complete, of course, but is pretty good against older strains of ransomware. The site is a joint effort by Europol, the Dutch police, Kaspersky, and McAfee.

from https://www.schneier.com/blog/