From 7710c0d681a4b5f17253945dde0726de0e27cdcf Mon Sep 17 00:00:00 2001
From: Raimo Niskanen <raimo@erlang.org>
Date: Thu, 28 Sep 2017 14:48:44 +0200
Subject: Make cache size configurable

---
 lib/crypto/doc/src/crypto.xml     | 14 ++++++++++++++
 lib/crypto/doc/src/crypto_app.xml | 18 ++++++++++++++++++
 2 files changed, 32 insertions(+)

(limited to 'lib/crypto/doc')

diff --git a/lib/crypto/doc/src/crypto.xml b/lib/crypto/doc/src/crypto.xml
index 5afab632cd..c32e3430ab 100644
--- a/lib/crypto/doc/src/crypto.xml
+++ b/lib/crypto/doc/src/crypto.xml
@@ -800,6 +800,7 @@ _FloatValue = rand:uniform().     % [0.0; 1.0[</pre>
         <v>Alg = crypto | crypto_cache</v>
       </type>
       <desc>
+	<marker id="rand_seed_alg-1" />
 	<p>
           Creates state object for
 	  <seealso marker="stdlib:rand">random number generation</seealso>,
@@ -814,6 +815,12 @@ _FloatValue = rand:uniform().     % [0.0; 1.0[</pre>
 	  may throw exception <c>low_entropy</c> in case the random generator
 	  failed due to lack of secure "randomness".
 	</p>
+	<p>
+	  The cache size can be changed from its default value using the
+	  <seealso marker="crypto_app">
+	    crypto app's
+	  </seealso> configuration parameter <c>rand_cache_size</c>.
+	</p>
         <p><em>Example</em></p>
         <pre>
 _ = crypto:rand_seed_alg(crypto_cache),
@@ -829,6 +836,7 @@ _FloatValue = rand:uniform().     % [0.0; 1.0[</pre>
         <v>Alg = crypto | crypto_cache</v>
       </type>
       <desc>
+	<marker id="rand_seed_alg_s-1" />
 	<p>
           Creates state object for
 	  <seealso marker="stdlib:rand">random number generation</seealso>,
@@ -852,6 +860,12 @@ _FloatValue = rand:uniform().     % [0.0; 1.0[</pre>
 	  may throw exception <c>low_entropy</c> in case the random generator
 	  failed due to lack of secure "randomness".
 	</p>
+	<p>
+	  The cache size can be changed from its default value using the
+	  <seealso marker="crypto_app">
+	    crypto app's
+	  </seealso> configuration parameter <c>rand_cache_size</c>.
+	</p>
 	<note>
 	  <p>
 	    The state returned from this function can not be used
diff --git a/lib/crypto/doc/src/crypto_app.xml b/lib/crypto/doc/src/crypto_app.xml
index ba22557480..8296b1bc77 100644
--- a/lib/crypto/doc/src/crypto_app.xml
+++ b/lib/crypto/doc/src/crypto_app.xml
@@ -68,6 +68,24 @@
         thus the crypto module will fail to load. This mechanism
         prevents the accidental use of non-validated algorithms.</p>
       </item>
+      <tag><c>rand_cache_size = integer()</c></tag>
+      <item>
+        <p>
+	  Sets the cache size in bytes to use by
+	  <seealso marker="crypto#rand_seed_alg-1">
+	    <c>crypto:rand_seed_alg(crypto_cache)</c>
+	  </seealso> and
+	  <seealso marker="crypto#rand_seed_alg_s-1">
+	    <c>crypto:rand_seed_alg_s(crypto_cache)</c>
+	  </seealso>.
+	  This parameter is read when a seed function is called,
+	  and then kept in generators state object.  It has a rather
+	  small default value that causes reads of strong random bytes
+	  about once per hundred calls for a random value.
+	  The set value is rounded up to an integral number of words
+	  of the size these seed functions use.
+	</p>
+      </item>
     </taglist>
   </section>
 
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