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authorRob Austein <sra@hactrn.net>2020-09-13 23:04:30 +0000
committerRob Austein <sra@hactrn.net>2020-09-13 23:04:30 +0000
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tree6fabf690f1ebf485a9fea9af5298e44ad2a59a3e /raw-wiki-dump/GitRepositories%2Fcore%2Frng%2Favalanche_entropy
parent9d927e49d9c10fc16c6dfa4a2a96cdb6216e4e2b (diff)
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+{{{
+#!htmlcomment
+
+This page is maintained automatically by a script. Don't modify this page by hand,
+your changes will just be overwritten the next time the script runs. Talk to your
+Friendly Neighborhood Repository Maintainer if you need to change something here.
+
+}}}
+
+{{{
+#!html
+<h1>avalanche_entropy</h1>
+
+<p>Entropy provider core for an external avalanche noise based entropy source.</p>
+
+<h2>Functional Description</h2>
+
+<p>This core samples noise provided on an input pin. The noise is expected
+to be 'digital' that is fairly rapidly move from voltage levels
+matching ones and zeros as handled by the digital process used to
+implement the core.</p>
+
+<p>The noise is sampled with double registers. Then phase detection is
+applied to find positive flanks. The core contains a free running clock
+(clocked at the provided core clock frequency). When a positive flank in
+the noise is detected, the LSB of the clock is sampled and added to a
+shift registers. When at least 32 bits has been collected, the result is
+presented as entropy available to any entropy consumer connected to the
+core.</p>
+
+<p>The core also includes a delta time counter. This counter is used for
+testing of the core and is available via the API.</p>
+
+<p>The fact that the core uses the flank of the to drive the entropy bit
+generation, but that the timing between the flanks means that if
+the noise source have a bias for zero or one state does not affect which
+entropy bits are generated.</p>
+
+<h2>Implementation Status</h2>
+
+<p>The core has been tested with several revisions of the Cryptech
+avalanche noise board. The core has been implemented in Altera
+Cyclone-IV and Cyclone-V devices as well as in Xilinx Spartan-6
+devices. The core clock frequency used has been 25 MHz, 33 MHz and 50
+MHz.</p>
+
+<p>The generated entropy has been extensively tested (using the ent tool as
+well as other custom tools) and found to be generating entropy with good
+quality.</p>
+}}}
+
+[[RepositoryIndex(format=table,glob=core/rng/avalanche_entropy)]]
+
+|| Clone `https://git.cryptech.is/core/rng/avalanche_entropy.git` ||