Category Archives: Cryptography

Quantum Cryptography Done Over Shared Data Line

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Researchers have sent quantum keys over a "lit" fiber-optic network, a step towards using quantum cryptography on the networks businesses and institutions use every day.

A group of U.K.-based research groups last week said the demonstration opens the door to more research that will make the technology more commercially viable. The researchers were from Toshiba Research Europe, BT, ADVA Optical Networking, and the U.K.'s National Physical Laboratory (NPL).

In quantum cryptography, the keys to unlock the contents of communications are represented with photons. It starts with a laser that sends a pair of photons over a fiber-optic network.The polarization of photonswhether theyre oscillating horizontally or vertically, for examplecan be detected by a receiver and read as bits, which are used to generate the same encryption key at both ends of the network connection. If an interloper attempts to intercept the keys to decrypt a message, the receiver will be able to detect a change, according to the laws of quantum mechanics. If that happens, the receiver can reject the keys and the message stays encrypted.

Until now, quantum key distribution (QKD) has been done over dark fiber, or unused optical fiber lines, which means that a separate fiber optic line is needed for transmitting other data. But dark fiber networks are not always available and are expensive. Being able to transmit quantum keys over a lit fiber network means that institutions and businesses will be able to run quantum cryptography over their existing networking infrastructure, the researchers said.

"Using techniques to filter out noise from the very weak quantum signals, we've shown that QKD can be operated on optical fibers installed in the ground and carrying conventional data signals," said Andrew Shields from Toshiba Research Europe in a statement.

The National Physics Laboratory developed a series of measurements for identifying individual particles of light from the stream of photons sent over a fiber-optic line. That will allow the system to detect attempts to intercept the transmission of keys, which should improve customer confidence in quantum cryptography, said Alastair Sinclair from the National Physics Laboratory in a statement.

The test was conducted over a live BT fiber link between its research campus in Suffolk and another BT site in Ipswich, U.K. In an interview with Nature, Toshiba's Shields said the quantum key distribution was done alongside data transmitted at 40 gigabits per second, the fastest multiplexing of regular data with quantum keys to date. But he notes that implementing QKD in the "real world" is more challenging than a laboratory environment because there are environmental fluctuations that can cause data loss in fiber lines.

Another technical challenge facing widespread use of QKD is the distance keys can be sent. Light pulses sent over a fiber optic line fade, which means that key distribution can only be done at a distance of about 100 kilometers. (See Long-Distance Quantum Cryptography.) But as governments and companies seek out the most secure ways to send data, quantum cryptography could become an appealing option.

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Quantum Cryptography Done Over Shared Data Line

ShmooCon 2014: History of Bletchley Park and How They Invented Cryptography and the Computer Age – Video

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ShmooCon 2014: History of Bletchley Park and How They Invented Cryptography and the Computer Age
For more information visit: http://bit.ly/shmooc14 To download the video visit: http://bit.ly/shmooc14_down Playlist Shmoocon 2014: http://bit.ly/shmooc14_pl Speaker: Benjamin Gatti In the...

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ShmooCon 2014: History of Bletchley Park and How They Invented Cryptography and the Computer Age - Video

ShmooCon 2014: SafeCurves: Choosing Safe Curves for Elliptic-Curve Cryptography – Video

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ShmooCon 2014: SafeCurves: Choosing Safe Curves for Elliptic-Curve Cryptography
For more information visit: http://bit.ly/shmooc14 To download the video visit: http://bit.ly/shmooc14_down Playlist Shmoocon 2014: http://bit.ly/shmooc14_pl Speakers: Daniel J. Bernstein...

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ShmooCon 2014: SafeCurves: Choosing Safe Curves for Elliptic-Curve Cryptography - Video

NIST removes cryptography algorithm from random number generator recommendations

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15 hours ago by Jennifer Huergo

Following a public comment period and review, the National Institute of Standards and Technology (NIST) has removed a cryptographic algorithm from its draft guidance on random number generators. Before implementing the change, NIST is requesting final public comments on the revised document, Recommendation for Random Number Generation Using Deterministic Random Bit Generators (NIST Special Publication 800-90A, Rev. 1).

The revised document retains three of the four previously available options for generating pseudorandom bits needed to create secure cryptographic keys for encrypting data. It omits an algorithm known as Dual_EC_DRBG, or Dual Elliptic Curve Deterministic Random Bit Generator. NIST recommends that current users of Dual_EC_DRBG transition to one of the three remaining approved algorithms as quickly as possible.

In September 2013, news reports prompted public concern about the trustworthiness of Dual_EC_DRBG. As a result, NIST immediately recommended against the use of the algorithm and reissued SP 800-90A for public comment.

Some commenters expressed concerns that the algorithm contains a weakness that would allow attackers to figure out the secret cryptographic keys and defeat the protections provided by those keys. Based on its own evaluation, and in response to the lack of public confidence in the algorithm, NIST removed Dual_EC_DRBG from the Rev. 1 document.

The revised SP 800-90A is available at csrc.nist.gov/news_events/index.html#apr21 along with instructions for submitting comments. The public comment period closes on May 23, 2014. NIST will take those comments into consideration in making any revisions to SP 800-90A.

NIST recommends that vendors currently using Dual_EC_DRBG who want to remain in compliance with federal guidance, and who have not yet made the previously recommended changes to their cryptographic modules, should select an alternative algorithm and not wait for further revision of the Rev. 1 document.

NIST advises federal agencies and other buyers of cryptographic products to ask vendors if their cryptographic modules rely on Dual_EC_DRBG, and if so, to ask their vendors to reconfigure those products to use alternative algorithms.

A list of cryptographic modules that include Dual_EC_DRBG can be found at http://csrc.nist.gov/groups/STM/cavp/documents/drbg/drbgval.html. Most of these modules implement more than one random number generator. In some cases, the Dual_EC_DRBG algorithm may be listed as included in a product, but another approved algorithm may be used by default. If a product uses Dual_EC_DRBG as the default random number generator, it may be possible to reconfigure the product to use a different default algorithm.

Draft versions of related guidance, 800-90 B: Recommendation for the Entropy Sources Used for Random Bit Generation and 800-90 C: Recommendation for Random Bit Generator (RBG) Constructions, were also released for comment in September 2013 and are still under development.

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How Heartbleed transformed HTTPS security into the stuff of absurdist theater

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If you want to protect yourself against the 500,000 or so HTTPS certificates that may have been compromised by the catastrophic Heartbleed bug, don't count on the revocation mechanism built-in to your browser. It doesn't do what its creators designed it to do, and switching it on makes you no more secure than leaving it off, one of the Internet's most respected cryptography engineers said over the weekend.

Four people have been able to see server keys and certificates in a test.

Certificate revocation is the process of a browser or other application performing an online lookup to confirm that a TLS certificate hasn't been revoked. The futility of certificate revocation was most recently discussed in a blog post published Saturday by Adam Langley, an engineer who was writing on his own behalf but who also handles important cryptography and security issues at Google. In the post, Langley recites a litany of technical considerations that have long prevented real-time online certificate revocations from thwarting attackers armed with compromised certificates, even when the digital credentials have been recalled. Some of the considerations include:

"That's why I claim that revocation checking is uselessbecause it doesn't stop attacks," Langley wrote. "Turning it on does nothing but slow things down. You can tell when something is security theater because you need some absurdly specific situation in order for it to be useful."

Langley's blog post helps explain why Google Chrome by default doesn't have online revocation enabled. In the aftermath of Heartbleed, many people have counseled turning it on. That's because the OpenSSL bug allows attackers to pluck passwords, authentication cookies, and even private encryption keys out of the computer memory of vulnerable servers. In many cases, there is no way to know if the two-year-old flaw has been exploited. As a result, security experts have counseled people administering vulnerable websites to assume the key bound to their old TLS certificate is compromised. That has meant getting a new certificate and revoking the old one.

Online certificate checking is the mechanism many have assumed would prevent end users from trusting revoked credentials. Certificate revocation by sites remains a good idea, but in light of this weekend's post, end users shouldn't assume OCSP will do much to flag old compromised keys that may be presented by attackers.

An IETF proposal hopes to mend cracks in the Internet's foundation of trust.

The Heartbleed debacle is by no means the first event to underscore the inadequacy of current TLS revocation. A variety of researchers have proposed alternatives. One such fix, devised by cryptography experts Moxie Marlinspike and Trevor Perrin, is known as TACK. Another one was created by a developer from Red Hat and is dubbed Mutually Endorsing CA Infrastructure. Langley, meanwhile, held out something called OCSP Must Staple.

Those proposals and several others like them have largely languished in inertia. If there's a silver lining to Heartbleed, it may be that it provides the catalyst that the huge number of the world's engineers will need to finally fix one of the Internet's biggest security holes.

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How Heartbleed transformed HTTPS security into the stuff of absurdist theater

Bitcoin SF Devs Seminar: Let’s go deep into cryptography principles with Pavel – Video

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Bitcoin SF Devs Seminar: Let #39;s go deep into cryptography principles with Pavel
SF Bitcoin Dev Pavel Kravchenko squeezes a few years of cryptography instruction into one tiny 55 minute presentation. WARNING: Dense content! Watch with cof...

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Bitcoin SF Devs Seminar: Let's go deep into cryptography principles with Pavel - Video