50 lines
1.9 KiB
HTML
50 lines
1.9 KiB
HTML
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<!DOCTYPE html>
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<html>
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<head>
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<meta charset="UTF-8">
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<style type="text/css">
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code { color: green; }
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pre { margin-left: 3em; }
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</style>
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<!-- INSERT LATCH JS -->
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</head>
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<body style="margin: 0 auto; width: 40em; text-align: left;">
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<!-- INSERT LATCH HTML -->
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<h1>Generating Random Bits for RAPPOR</h1>
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<p>To ensure privacy, an application using RAPPOR must generate random bits in an
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unpredictable manner. In other words, an adversary that can predict the
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sequence of random bits used can determine the true values being reported.</p>
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<p>Generating random numbers is highly platform-specific -- even
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language-specific. So, libraries implementing RAPPOR should be parameterized
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by an interface to generate random bits. (This can be thought of as
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"dependency injection".)</p>
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<!-- TODO: details on the interfaces, once we have them in more than one
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language -->
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<p>For now, we have collected some useful links.</p>
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<h2>Linux</h2>
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<ul>
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<li><p><a href="http://www.2uo.de/myths-about-urandom/">Myths about /dev/urandom</a> -- Nice
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article explaining implementation aspects of <code>/dev/urandom</code> and <code>/dev/random</code>
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on Linux. (Summary: just use <code>/dev/urandom</code>, with caveats explained)</p></li>
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<li><p><a href="http://lwn.net/Articles/606141/">LWN on getrandom</a>
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(<a href="http://lwn.net/Articles/605828/">patch</a>) -- A very recent addition to the
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Linux kernel. As of this writing (11/2014), it's safe to say that very few
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applications use it. The relevant change, involving an issue mentioned in
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the first link, involves the situation at system boot, when there is little
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entropy available.</p></li>
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</ul>
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<!-- TODO: other platforms. Chrome uses /dev/urandom on Linux. What about
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other platforms? -->
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<!-- TODO: when we have a C/C++ client, explain provide sample implementation
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using simple C functions -->
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</body>
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</html>
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