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Critical PGP Vulnerability

EFF is reporting that a critical vulnerability has been discovered in PGP and S/MIME. No details have been published yet, but one of the researchers wrote:

We’ll publish critical vulnerabilities in PGP/GPG and S/MIME email encryption on 2018-05-15 07:00 UTC. They might reveal the plaintext of encrypted emails, including encrypted emails sent in the past. There are currently no reliable fixes for the vulnerability. If you use PGP/GPG or S/MIME for very sensitive communication, you should disable it in your email client for now.

This sounds like a protocol vulnerability, but we’ll learn more tomorrow.

News articles.

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LC4: Another Pen-and-Paper Cipher

Interesting symmetric cipher: LC4:

Abstract: ElsieFour (LC4) is a low-tech cipher that can be computed by hand; but unlike many historical ciphers, LC4 is designed to be hard to break. LC4 is intended for encrypted communication between humans only, and therefore it encrypts and decrypts plaintexts and ciphertexts consisting only of the English letters A through Z plus a few other characters. LC4 uses a nonce in addition to the secret key, and requires that different messages use unique nonces. LC4 performs authenticated encryption, and optional header data can be included in the authentication. This paper defines the LC4 encryption and decryption algorithms, analyzes LC4’s security, and describes a simple appliance for computing LC4 by hand.

Almost two decades ago I designed Solitaire, a pen-and-paper cipher that uses a deck of playing cards to store the cipher’s state. This algorithm uses specialized tiles. This gives the cipher designer more options, but it can be incriminating in a way that regular playing cards are not.

Still, I like seeing more designs like this.

Hacker News thread.

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Two NSA Algorithms Rejected by the ISO

The ISO has rejected two symmetric encryption algorithms: SIMON and SPECK. These algorithms were both designed by the NSA and made public in 2013. They are optimized for small and low-cost processors like IoT devices.

The risk of using NSA-designed ciphers, of course, is that they include NSA-designed backdoors. Personally, I doubt that they’re backdoored. And I always like seeing NSA-designed cryptography (particularly its key schedules). It’s like examining alien technology.

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Attack on Old ANSI Random Number Generator

Almost 20 years ago, I wrote a paper that pointed to a potential flaw in the ANSI X9.17 RNG standard. Now, new research has found that the flaw exists in some implementations of the RNG standard.

Here’s the research paper, the website — complete with cute logo — for the attack, and Matthew Green’s excellent blog post on the research.

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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.

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NSA Brute-Force Keysearch Machine

The Intercept published a story about a dedicated NSA brute-force keysearch machine being built with the help of New York University and IBM. It’s based on a document that was accidentally shared on the Internet by NYU.

The article is frustratingly short on details:

The WindsorGreen documents are mostly inscrutable to anyone without a Ph.D. in a related field, but they make clear that the computer is the successor to WindsorBlue, a next generation of specialized IBM hardware that would excel at cracking encryption, whose known customers are the U.S. government and its partners.

Experts who reviewed the IBM documents said WindsorGreen possesses substantially greater computing power than WindsorBlue, making it particularly adept at compromising encryption and passwords. In an overview of WindsorGreen, the computer is described as a “redesign” centered around an improved version of its processor, known as an “application specific integrated circuit,” or ASIC, a type of chip built to do one task, like mining bitcoin, extremely well, as opposed to being relatively good at accomplishing the wide range of tasks that, say, a typical MacBook would handle. One of the upgrades was to switch the processor to smaller transistors, allowing more circuitry to be crammed into the same area, a change quantified by measuring the reduction in nanometers (nm) between certain chip features.

Unfortunately, the Intercept decided not to publish most of the document, so all of those people with “a Ph.D. in a related field” can’t read and understand WindsorGreen’s capabilities. What sorts of key lengths can the machine brute force? Is it optimized for symmetric or asymmetric cryptanalysis? Random brute force or dictionary attacks? We have no idea.

Whatever the details, this is exactly the sort of thing the NSA should be spending their money. Breaking the cryptography used by other nations is squarely in the NSA’s mission.

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Kalyna Block Cipher

Kalyna is a block cipher that became a Ukrainian national standard in 2015. It supports block and key sizes of 128, 256, and 512 bits. Its structure looks like AES but optimized for 64-bit CPUs, and it has a complicated key schedule. Rounds range from 10-18, depending on block and key sizes.

There is some mention of cryptanalysis on reduced-round versions in the Wikipedia entry. And here are the other submissions to the standard.

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Twofish Power Analysis Attack

New paper: “A Simple Power Analysis Attack on the Twofish Key Schedule.” This shouldn’t be a surprise; these attacks are devastating if you don’t take steps to mitigate them.

The general issue is if an attacker has physical control of the computer performing the encryption, it is very hard to secure the encryption inside the computer. I wrote a paper about this back in 1999.

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