• Tag Archives security

  • Cryptographers Demonstrate Collision in Popular SHA-1 Algorithm

    Posted on by Azrael Comment

    On February 23rd, a joint team from the CWI Amsterdam and Google announced that they had generated the first ever collision in the SHA-1 cryptographic hashing algorithm. SHA-1 has long been considered theoretically insecure by cryptanalysts due to weaknesses in the algorithm design, but this marks the first time researchers were actually able to demonstrate a real-world example of the insecurity. In addition to being a powerful Proof of Concept (POC), the computing power that went into generating the proof was notable:

    We then leveraged Google’s technical expertise and cloud infrastructure to compute the collision which is one of the largest computations ever completed.

    Here are some numbers that give a sense of how large scale this computation was:

    • Nine quintillion (9,223,372,036,854,775,808) SHA1 computations in total
    • 6,500 years of CPU computation to complete the attack first phase
    • 110 years of GPU computation to complete the second phase

    The CWI Amsterdam and Google researchers launched shattered.io, a site explaining the attack and linking to two distinct pdf files: shattered-1.pdf and shattered-2.pdf with different contents but the same SHA-1 checksum.

    What is SHA-1, anyway?

    SHA-1 is part of a class of algorithms known as collision-resistant hashing functions, which create a short digest of some arbitrary data. That can be a piece of text, a database entry, or a file, just to name a few examples. For instance, the SHA-1 result or ‘checksum’ of the first sentence in this paragraph is 472825ab28b45d64cd234a22398bba755dd56485. Creating a digest of data is useful in many contexts. For example, making a cryptographic signature for a digest is more convenient and faster than signing the entire contents of a message, a fact that many cryptographic systems have taken advantage of. Lots of software uses this type of hashing function, and relies on the collision-resistance property to verify that the contents of the original message haven’t been corrupted or tampered with.

    Sunsetting SHA-1

    While a brute-force attack (simply trying all the possibilities until a collision is found) remains impractical, low-level analysis of the algorithm has revealed deep fractures in its design. Over time, as these theoretical attacks against the algorithm have gotten better, many have moved away from SHA-1 to guarantee security. In 2014, the CA Browser Forum (an organization which comprises the trust-roots for the web) passed a ballot which prevented new HTTPS certificates from being issued using SHA-1 after 2015. And earlier this year, the major browsers started to remove support for HTTPS sites which serve SHA-1 certificates. In general, companies and software projects were moving away from relying on SHA-1. Next-generation hashing algorithms such as SHA-256 and SHA-3 have been available for a long time, and provide far better guarantees against collisions.

    So what’s the big deal?

    Unfortunately, the migration away from SHA-1 has not been universal. Some programs, such as the version control system Git, have SHA-1 hard-baked into its code. This makes it difficult for projects which rely on Git to ditch the algorithm altogether. The encrypted e-mail system PGP also relies on it in certain places.

    While initially promising to deprecate SHA-1 in a similar time-frame as the other browsers, Internet Explorer has pushed that date back to mid-2017. This means that sites with certificates signed by the insecure function will still be trusted for IE users. And while the collision was demonstrated on two pdf files, there is nothing stopping others from crafting a malicious X.509 certificate with the same checksum as a valid certificate, and using that to impersonate a legitimate HTTPS site. History (and Moore’s law) shows us that this only becomes easier over time. The first full collision of the then-popular MD5 hashing algorithm was demonstrated in August 2004. Less than seven months later, an X.509 collision was shown.

    Last year, we pointed out that a SHA-1 collision in 2017 was entirely foreseeable, and will happen again in the future. To have robust protections against cryptographic vulnerabilities, software projects have to take these vulnerabilities seriously before they turn into demonstrated attacks, when they are still theoretical but within the realm of possibility. Otherwise, the time it takes to migrate away from these insecure algorithms will be well used by attackers, as well.



    Source: Cryptographers Demonstrate Collision in Popular SHA-1 Algorithm | Electronic Frontier Foundation


    📂This entry was posted in Computer Arcana News and Politics 📎and tagged

  • Digital Security Tips for Protesters

    Posted on by Azrael Comment

    After the election, individuals took to the streets across the country to express their outrage and disappointment at the result of the U.S. presidential election. Many protesters may not be aware of the unfortunate fact that exercising their First Amendment rights may open themselves up to certain risks. Those engaging in peaceful protest may be subject to search or arrest, have their movements and associations mapped, or otherwise become targets of surveillance and repression. It is important that in a democracy citizens exercise their right to peaceably assemble, and demonstrators should be aware of a few precautions they can take to keep themselves and their data safe. Here we present 10 security tips for protesting in the digital age.

    1. Enable full-disk encryption on your device

    Full-disk encryption ensures that the files across your entire device are encrypted. This is a form of encryption that protects data at rest, as compared to in-transit encryption, which protects data that is transferred over the Internet. Full-disk encryption protects everything from your local database of text messages to the passwords you have stored in your browser. This is useful in case your device is confiscated by police, but also protects you in situations where the device is lost or stolen. Protest situations are often unpredictable, so losing your phone is distinct possibility.

    Recent versions of Android and iOS require full-disk encryption capabilities to be built into devices. These should be protected by a strong password, 8-12 random characters that are nonetheless easy to remember and type in when you unlock your device. If devices are not protected by a strong password, the encryption may be easier to break using a brute force attack.Recent editions of the iPhone have employed specialized hardware to protect against this type of attack, but a complex password is still advisable.

    1. Remove fingerprint unlock

    In the past, iOS and Android used the same password to both boot your phone and to unlock it. Recently, both iOS and Android introduced a mechanism to allow you to unlock your device with your fingerprint. This is a convenient way to ensure that you enjoy the benefits of full-disk encryption without sacrificing convenience. However, in protest situations we suggest you turn this functionality off. A police officer can physically force you to unlock your device with your fingerprint. And as a legal matter, while the state of the law is in flux, there is currently less protection against compelled fingerprint unlocking than compelled password disclosure. You can always add your fingerprint back to the device after you’ve left the protest.

    In iOS, you can disable this by going into Settings -> Touch ID & Passcode and removing each of the fingerprints in this menu.

    In Android, disabling this feature may depend on your device manufacturer. For Nexus devices, go into Settings -> Security -> Nexus Imprint and delete the fingerprints from this menu.

    1. Take photos and videos without unlocking your device

    Catching that perfect shot is something you want to be ready for, and powerful images can help bolster the cause. If you’ve chosen a strong password, entering it into the device takes precious time, and you risk the moment passing before you’re able to take the shot. Luckily, newer versions of iOS and Android allow you to take photos and videos without unlocking your device, giving you the time to capture the moment.

    With Android Nexus devices, double-press the power button.

    At the iOS lock screen, you can swipe to the right.

    1. Install Signal

    Signal is an app available on both iOS and Android that offers strong encryption to protect both text messages and voice calls. This type of protection is called end-to-end encryption, which secures your communications in transit (as discussed in tip #1). Other apps, such as WhatsApp, have implemented underlying cryptography. But we believe Signal is the better option because it implements best practices for secure messaging.

    In addition to encrypting one-to-one communication, Signal enables encrypted group chats. The app also recently added the functionality of having messages disappear ranging anywhere from 10 seconds to a week after they are first read. In contrast to some other services like SnapChat, these ephemeral messages will never be stored on any server, and are removed from your device after disappearing.

    Recently, a grand jury in the Eastern District of Virginia issued a subpoena to Open Whisper Systems, the maintainers of Signal. Because of the architecture of Signal, which limits the user metadata stored on the company’s servers, the only data they were able to provide was “the date and time a user registered with Signal and the last date of a user’s connectivity to the Signal service.”

    1. Read our Surveillance Self Defense (SSD) guide for street-level protests

    Know your rights when attending protests with our SSD module on the topic: https://ssd.eff.org/en/module/attending-protests-united-states

    1. Use a prepaid, disposable phone

    If you’re really concerned with the data stored on your device, don’t bring it at all and pick up a prepaid mobile phone. These lower-end devices can be purchased along with a SIM card at most large retail stores, and current federal regulation does not require you to show your ID (but your state may). Let your friends know your temporary number, and use this to coordinate activities. Remember that the location of mobile devices can be determined by the cell towers they connect to, so if you don’t want your identity known, turn off your prepaid device before going home or anywhere that might lead to your identity. Using GPS should be safe, since GPS is a receiver and does not transmit any information, but your device may store your coordinates. For this reason, we suggest you turn off location services. When you’re done with the phone, it can be safely recycled or discarded from a location that is not linked to you. Keep in mind that if you carry both your regular device and a prepaid one with you, the location of these devices can be correlated as a way to compromise your anonymity.

    1. Back up your data

    Take precautions to limit the possible costs that can be incurred by the loss of a device. Backing up your data regularly and storing that backup in a safe place can save you a headache later on.

    1. Consider biking or walking to the protest

    Automated License Plate Reader Systems (ALPRs) automatically record the license plates of cars driving through an area, along with the exact time, date, and location they were encountered. This technology is often used by law enforcement, or employed by private companies such as Vigilant and MVTrac who then share license plate data with law enforcement and other entities. Amassed in huge databases, this data is retained for an unknown period of time. These companies have lobbied and litigated vigorously against statutes that would ban the private collection of license plate data or otherwise regulate ALPRs. Effectively, your location can be tracked over time by your driving habits, with very few legal limits in place as to how this data can be collected and accessed.

    Consider using alternative means of transportation if you would prefer that your movements and associations remain private.

    Read more in our Street Level Surveillance guide on ALPRs.

    1. Enable airplane mode

    Airplane mode ensures that your device will not be transmitting for the duration of your time at the protest, and prevents your location from being tracked. Clearly, this also means that you won’t be able to message or call your friends, so plan accordingly. You may want to select a nearby meet up spot where you and your friends can rendezvous if you get separated. You may also want to turn off location services (as discussed in tip #6).

    1. Organizers: consider alternatives to Facebook and Twitter

    Facebook and Twitter provide a large user base for you to promote your cause, but these popular social media platforms also carry risks. Viewing an event page, commenting on the event, and stating your intention to attend are all actions viewable by law enforcement if the pages and posts are public, and sometimes even if the pages aren’t (subject to a court order). For actions that require a more cautious approach, consider forming a group chat via Signal as described above.

    Source: Digital Security Tips for Protesters | Electronic Frontier Foundation


    📂This entry was posted in Computer Arcana 📎and tagged

  • Obama Should Reject Anti-Encryption Legislation and Protect Digital Security

    Posted on by Azrael Comment

    Dozens of nonprofit organizations, companies, and academics sent a joint letter today urging President Obama to take a strong stance against backdoors and oppose legislation that would undermine security.

    The coalition effort—which included EFF, Access Now, Fight for the Future, and others— was organized after The Hill published a draft of anti-security legislation written by Senators Richard Burr (R-NC) and Dianne Feinstein (D-CA). The draft bill would create a new obligationon device manufacturers, software developers, ISPs, online services and others to decrypt encrypted data or offer “such technical assistance as is necessary” if ordered to do so by any court in the country.

    From the joint letter:

    It is beyond dispute that this bill would threaten the safety of billions of internet users, including journalists, activists, and ordinary people exercising their right to free expression, as well as critical infrastructure systems and government databases. However, it would likely to do very little to assist in investigations of crime or terrorism, since those who engage in illegal activities will have access to other means to protect their own devices and communications.

    Today’s letter comes 167 days after the pro-encryption petition at SaveCrypto.org surpassed 100,000 signatures, achieving the threshold for receiving an official response from the president. To date, there has still been no substantive response from the administration. The White House has “aimed” to respond to petitions with 100,000 signatures within 60 days.

    Read the full letter to President Obama. Speak out against the Burr-Feinstein proposal.

    Source: Obama Should Reject Anti-Encryption Legislation and Protect Digital Security | Electronic Frontier Foundation

    📂This entry was posted in News and Politics 📎and tagged