Entries Tagged "cryptography"

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Susan Landau's New Book: Listening In

Susan Landau has written a terrific book on cybersecurity threats and why we need strong crypto. Listening In: Cybersecurity in an Insecure Age. It’s based in part on her 2016 Congressional testimony in the Apple/FBI case; it examines how the Digital Revolution has transformed society, and how law enforcement needs to—and can—adjust to the new realities. The book is accessible to techies and non-techies alike, and is strongly recommended.

And if you’ve already read it, give it a review on Amazon. Reviews sell books, and this one needs more of them.

Posted on January 10, 2018 at 1:42 PM • View Comments

"Crypto" Is Being Redefined as Cryptocurrencies

I agree with Lorenzo Franceschi-Bicchierai, “Cryptocurrencies aren’t ‘crypto’“:

Lately on the internet, people in the world of Bitcoin and other digital currencies are starting to use the word “crypto” as a catch-all term for the lightly regulated and burgeoning world of digital currencies in general, or for the word “cryptocurrency”—which probably shouldn’t even be called “currency,” by the way.

[…]

To be clear, I’m not the only one who is mad about this. Bitcoin and other technologies indeed do use cryptography: all cryptocurrency transactions are secured by a “public key” known to all and a “private key” known only to one party­—this is the basis for a swath of cryptographic approaches (known as public key, or asymmetric cryptography) like PGP. But cryptographers say that’s not really their defining trait.

“Most cryptocurrency barely has anything to do with serious cryptography,” Matthew Green, a renowned computer scientist who studies cryptography, told me via email. “Aside from the trivial use of digital signatures and hash functions, it’s a stupid name.”

It is a stupid name.

Posted on December 4, 2017 at 9:14 AM • View Comments

Security Flaw in Infineon Smart Cards and TPMs

A security flaw in Infineon smart cards and TPMs allows an attacker to recover private keys from the public keys. Basically, the key generation algorithm sometimes creates public keys that are vulnerable to Coppersmith’s attack:

While all keys generated with the library are much weaker than they should be, it’s not currently practical to factorize all of them. For example, 3072-bit and 4096-bit keys aren’t practically factorable. But oddly enough, the theoretically stronger, longer 4096-bit key is much weaker than the 3072-bit key and may fall within the reach of a practical (although costly) factorization if the researchers’ method improves.

To spare time and cost, attackers can first test a public key to see if it’s vulnerable to the attack. The test is inexpensive, requires less than 1 millisecond, and its creators believe it produces practically zero false positives and zero false negatives. The fingerprinting allows attackers to expend effort only on keys that are practically factorizable.

This is the flaw in the Estonian national ID card we learned about last month.

The paper isn’t online yet. I’ll post it when it is.

Ouch. This is a bad vulnerability, and it’s in systems—like the Estonian national ID card—that are critical.

EDITED TO ADD (11/14): More information from the researchers.

Posted on October 17, 2017 at 9:24 AM • View Comments

ISO Rejects NSA Encryption Algorithms

The ISO has decided not to approve two NSA-designed block encryption algorithms: Speck and Simon. It’s because the NSA is not trusted to put security ahead of surveillance:

A number of them voiced their distrust in emails to one another, seen by Reuters, and in written comments that are part of the process. The suspicions stem largely from internal NSA documents disclosed by Snowden that showed the agency had previously plotted to manipulate standards and promote technology it could penetrate. Budget documents, for example, sought funding to “insert vulnerabilities into commercial encryption systems.”

More than a dozen of the experts involved in the approval process for Simon and Speck feared that if the NSA was able to crack the encryption techniques, it would gain a “back door” into coded transmissions, according to the interviews and emails and other documents seen by Reuters.

“I don’t trust the designers,” Israeli delegate Orr Dunkelman, a computer science professor at the University of Haifa, told Reuters, citing Snowden’s papers. “There are quite a lot of people in NSA who think their job is to subvert standards. My job is to secure standards.”

I don’t trust the NSA, either.

Posted on September 21, 2017 at 5:50 AM • View Comments

Proof that HMAC-DRBG has No Back Doors

New research: “Verified Correctness and Security of mbedTLS HMAC-DRBG,” by Katherine Q. Ye, Matthew Green, Naphat Sanguansin, Lennart Beringer, Adam Petcher, and Andrew W. Appel.

Abstract: We have formalized the functional specification of HMAC-DRBG (NIST 800-90A), and we have proved its cryptographic security—that its output is pseudorandom—using a hybrid game-based proof. We have also proved that the mbedTLS implementation (C program) correctly implements this functional specification. That proof composes with an existing C compiler correctness proof to guarantee, end-to-end, that the machine language program gives strong pseudorandomness. All proofs (hybrid games, C program verification, compiler, and their composition) are machine-checked in the Coq proof assistant. Our proofs are modular: the hybrid game proof holds on any implementation of HMAC-DRBG that satisfies our functional specification. Therefore, our functional specification can serve as a high-assurance reference.

Posted on August 30, 2017 at 6:37 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.