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faq [2010/04/28 13:15]
reinier created
faq [2010/04/28 13:26] (current)
reinier
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 For ubuntu (or other linux variants) intialization of the ''SecureRandom'' may be done using data from ''/dev/random''. This may be slow if the random device is low on entropy. You can configure to use ''/dev/urandom'' (unblocking random) or a hardware random generator instead. For ubuntu (or other linux variants) intialization of the ''SecureRandom'' may be done using data from ''/dev/random''. This may be slow if the random device is low on entropy. You can configure to use ''/dev/urandom'' (unblocking random) or a hardware random generator instead.
  
-=== untuntu ===+Urandom is less secure because it reuses some of the entropy data from the actual random device. However, the difference in initialization times can be dramatic. For example, it may take up to 30 seconds to get enough data from ''/dev/random'', while it would take only a few milliseconds for urandom.
  
-In ubuntu, urandom use can be configured by installing ''rng-tools'' package, and configuring it to use ''/dev/urandom'' as randomness source.+=== JVM argument === 
 + 
 +For java, you can specify which EGD (entropy gather daemon) you want to use by supplying a JVM argument. 
 + 
 +<code> 
 +-Djava.security.egd=file:/dev/./urandom 
 +</code> 
 + 
 + 
 +=== system-wide random settings === 
 + 
 +In ubuntu, system-wide urandom settings can be configured by installing ''rng-tools'' package, and configuring it to use ''/dev/urandom'' as randomness source. You will need super user privileges to install these tools.
  
 <code> <code>
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 </code> </code>
  
-You will need super user privileges to install these tools, but the difference in performance can be dramatic. For example, it may take up to 30 seconds to get enough data from ''/dev/random'', while it would take only a few milliseconds for urandom.+
faq.txt · Last modified: 2010/04/28 13:26 by reinier
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