MIT News: Encryption Is Less Secure Than We Thought

The problem, Médard explains, is that information-theoretic analyses of secure systems have generally used the wrong notion of entropy. They relied on so-called Shannon entropy, named after the founder of information theory, Claude Shannon, who taught at MIT from 1956 to 1978.

Shannon entropy is based on the average probability that a given string of bits will occur in a particular type of digital file. In a general-purpose communications system, that’s the right type of entropy to use, because the characteristics of the data traffic will quickly converge to the statistical averages. Although Shannon’s seminal 1948 paper dealt with cryptography, it was primarily concerned with communication, and it used the same measure of entropy in both discussions.

But in cryptography, the real concern isn’t with the average case but with the worst case. A codebreaker needs only one reliable correlation between the encrypted and unencrypted versions of a file in order to begin to deduce further correlations. In the years since Shannon’s paper, information theorists have developed other notions of entropy, some of which give greater weight to improbable outcomes. Those, it turns out, offer a more accurate picture of the problem of codebreaking.

When Médard, Duffy and their students used these alternate measures of entropy, they found that slight deviations from perfect uniformity in source files, which seemed trivial in the light of Shannon entropy, suddenly loomed much larger. The upshot is that a computer turned loose to simply guess correlations between the encrypted and unencrypted versions of a file would make headway much faster than previously expected.

“It’s still exponentially hard, but it’s exponentially easier than we thought,” Duffy says. One implication is that an attacker who simply relied on the frequencies with which letters occur in English words could probably guess a user-selected password much more quickly than was previously thought. “Attackers often use graphics processors to distribute the problem,” Duffy says. “You’d be surprised at how quickly you can guess stuff.”

More: Encryption Is Less Secure Than We Thought - MIT News Office

Jump to top

Create a PageThis is the LGF Pages posting bookmarklet. To use it, drag this button to your browser's bookmark bar, and title it 'LGF Pages' (or whatever you like). Then browse to a site you want to post, select some text on the page to use for a quote, click the bookmarklet, and the Pages posting window will appear with the title, text, and any embedded video or audio files already filled in, ready to go.
Or... you can just click this button to open the Pages posting window right away.
Last updated: 2016-01-01 10:29 am PST
LGF User's Guide RSS Feeds Tweet

Help support Little Green Footballs!

Subscribe now for ad-free access!Register and sign in to a free LGF account before subscribing, and your ad-free access will be automatically enabled.

Recent PagesClick to refresh
Timothy Caughman’s Murder Was a Lynching in Trump’s America. Just another day in Trumpmerica. The first thread that binds this killing to past lynchings is Jackson’s motivation. The self-proclaimed white supremacist told police that he hated black men in particular for their relationships with white women, a harkening ...
Tarkloon
4 hours, 8 minutes ago
Views: 90 • Comments: 0 • Rating: 0
Tweets: 0 • Share to Facebook
Shares: 0
Comments: 0
: 0
OneRepublic - A.I. (Audio) Ft. Peter GabrielGet OneRepublic’s new album ‘Oh My My,’ featuring ‘Kids,' 'Wherever I Go' and 'Let’s Hurt Tonight:’ smarturl.itListen to the Best of OneRepublic on Spotify: smarturl.it Music video by OneRepublic performing A.I.. (C) 2016 Mosley Music/Interscope Records vevo.ly
Tarkloon
4 hours, 27 minutes ago
Views: 73 • Comments: 0 • Rating: 0
Tweets: 0 • Share to Facebook
Shares: 0
Comments: 0
: 0
While Gorsuch Was Testifying, the Supreme Court Unanimously Said He Was Wrong About 40 minutes after Supreme Court nominee Neil Gorsuch began his second day of testimony before the Senate Judiciary Committee, all eight of the justices he hopes to join said a major disability decision Gorsuch wrote in 2008 was ...
Birth Control Works
1 day, 16 hours ago
Views: 202 • Comments: 0 • Rating: 2
Tweets: 0 • Share to Facebook
Shares: 0
Comments: 0
: 0
Black & Missing in America - a Short Film Published on May 7, 2015 From OSCAR® and 16-time EMMY award-winning producer Arnold Shapiro and Director/Producer Marlene McCurtis - a short film that highlights the work of the Black and Missing Foundation, and their quest to provide a voice ...
Birth Control Works
1 day, 16 hours ago
Views: 178 • Comments: 0 • Rating: 0
Tweets: 0 • Share to Facebook
Shares: 0
Comments: 0
: 0
500 Missing — Why You Should Pay Attention to DC’s Missing Girls if You Attended the Women’s March Though months have passed since the Women's March united women around the nation in January, its mission to stand up for the rights of those who are most vulnerable cannot afford to slip into the background. And this applies ...
Birth Control Works
1 day, 16 hours ago
Views: 220 • Comments: 0 • Rating: 0
Tweets: 1 • Share to Facebook
Shares: 0
Comments: 0
: 0
Rewire -‘Issues in Law & Medicine’: A One-Stop Journal for Anti-Vaccine, Anti-Abortion PseudoscienceUnsurprisingly creationists aren't the only ones who produce fake academic journals. It turns out that anti abortion, and anti vaccination ideologues do the same thing, only in the case of "Issues in Law & Medicine," the people behind it, arguably ...
CriticalDragon1177
1 day, 16 hours ago
Views: 268 • Comments: 0 • Rating: 0
Tweets: 0 • Share to Facebook
Shares: 0
Comments: 0
: 0
Trump Did to Merkel What Men Do to Women All the Time Tuesday 21 March 2017 06.00 EDT Last modified on Wednesday 22 March 2017 11.22 EDT A few years ago, my husband and I ran into a mutual acquaintance at a restaurant. This young man – a person who would ...
Birth Control Works
1 day, 17 hours ago
Views: 321 • Comments: 0 • Rating: 0
Tweets: 2 • Share to Facebook
Shares: 1
Comments: 0
: 1
RNC Paid Intel Firm for Clinton Dirt As the general election was taking shape last summer, the Republican National Committee initiated a series of payments to a low-profile firm started by retired CIA officers that worked closely with an ex-Russian spy. The payments attracted attention in ...
Birth Control Works
2 days ago
Views: 491 • Comments: 0 • Rating: 2
Tweets: 0 • Share to Facebook
Shares: 0
Comments: 0
: 0
Whatever You Do, Don’t Say Yes When This Chatbot Asks, ‘Can You Hear Me?’ Another in my irregular series on privacy in our era, and how to defend yourself in digital venues. For your cell phone-Get TruCaller or some other good robo call screener/blocker. If you have an Ooma phone, set your virtual ...
Unshaken Defiance
2 days, 1 hour ago
Views: 753 • Comments: 2 • Rating: 2
Tweets: 117 • Share to Facebook
Shares: 3
Comments: 0
: 3
NOT ONE WOMAN: What’s Missing From This Photo of Politicians Deciding the Future of Women’s Health? President Donald Trump met with the arch-conservative House Freedom Caucus at the White House Thursday to try to hammer out a deal on Obamacare repeal. A major question in the final negotiations? Whether or not maternity care and mammograms ...
Birth Control Works
2 days, 6 hours ago
Views: 387 • Comments: 0 • Rating: 0
Tweets: 0 • Share to Facebook
Shares: 0
Comments: 0
: 0