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-rw-r--r--lib/crypto/doc/src/crypto.xml114
1 files changed, 104 insertions, 10 deletions
diff --git a/lib/crypto/doc/src/crypto.xml b/lib/crypto/doc/src/crypto.xml
index 5c1909fc7f..3306fe3d16 100644
--- a/lib/crypto/doc/src/crypto.xml
+++ b/lib/crypto/doc/src/crypto.xml
@@ -1,4 +1,3 @@
-<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE erlref SYSTEM "erlref.dtd">
<erlref>
@@ -1011,7 +1010,7 @@ _FloatValue = rand:uniform(). % [0.0; 1.0[</pre>
</p>
<note>
<p>
- The state returned from this function can not be used
+ The state returned from this function cannot be used
to get a reproducable random sequence as from
the other
<seealso marker="stdlib:rand">rand</seealso>
@@ -1037,7 +1036,8 @@ _FloatValue = rand:uniform(). % [0.0; 1.0[</pre>
<p>
Creates state object for
<seealso marker="stdlib:rand">random number generation</seealso>,
- in order to generate cryptographically strong random numbers.
+ in order to generate cryptographically strong random numbers,
+ and saves it in the process dictionary before returning it as well.
See also
<seealso marker="stdlib:rand#seed-1">rand:seed/1</seealso> and
<seealso marker="#rand_seed_alg_s-1">rand_seed_alg_s/1</seealso>.
@@ -1048,12 +1048,6 @@ _FloatValue = rand:uniform(). % [0.0; 1.0[</pre>
may raise exception <c>error: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),
@@ -1063,6 +1057,34 @@ _FloatValue = rand:uniform(). % [0.0; 1.0[</pre>
</func>
<func>
+ <name since="OTP-22.0">rand_seed_alg(Alg, Seed) -> rand:state()</name>
+ <fsummary>Strong random number generation plugin state</fsummary>
+ <type>
+ <v>Alg = crypto_aes</v>
+ </type>
+ <desc>
+ <marker id="rand_seed_alg-2" />
+ <p>
+ Creates a state object for
+ <seealso marker="stdlib:rand">random number generation</seealso>,
+ in order to generate cryptographically unpredictable random numbers,
+ and saves it in the process dictionary before returning it as well.
+ See also
+ <seealso marker="#rand_seed_alg_s-2">rand_seed_alg_s/2</seealso>.
+ </p>
+ <p><em>Example</em></p>
+ <pre>
+_ = crypto:rand_seed_alg(crypto_aes, "my seed"),
+IntegerValue = rand:uniform(42), % [1; 42]
+FloatValue = rand:uniform(), % [0.0; 1.0[
+_ = crypto:rand_seed_alg(crypto_aes, "my seed"),
+IntegerValue = rand:uniform(42), % Same values
+FloatValue = rand:uniform(). % again
+ </pre>
+ </desc>
+ </func>
+
+ <func>
<name since="OTP 21.0">rand_seed_alg_s(Alg) -> rand:state()</name>
<fsummary>Strong random number generation plugin state</fsummary>
<type>
@@ -1099,9 +1121,15 @@ _FloatValue = rand:uniform(). % [0.0; 1.0[</pre>
crypto app's
</seealso> configuration parameter <c>rand_cache_size</c>.
</p>
+ <p>
+ When using the state object from this function the
+ <seealso marker="stdlib:rand">rand</seealso> functions using it
+ may throw exception <c>low_entropy</c> in case the random generator
+ failed due to lack of secure "randomness".
+ </p>
<note>
<p>
- The state returned from this function can not be used
+ The state returned from this function cannot be used
to get a reproducable random sequence as from
the other
<seealso marker="stdlib:rand">rand</seealso>
@@ -1121,6 +1149,72 @@ _FloatValue = rand:uniform(). % [0.0; 1.0[</pre>
</func>
<func>
+ <name since="OTP 22.0">rand_seed_alg_s(Alg, Seed) -> rand:state()</name>
+ <fsummary>Strong random number generation plugin state</fsummary>
+ <type>
+ <v>Alg = crypto_aes</v>
+ </type>
+ <desc>
+ <marker id="rand_seed_alg_s-2" />
+ <p>
+ Creates a state object for
+ <seealso marker="stdlib:rand">random number generation</seealso>,
+ in order to generate cryptographically unpredictable random numbers.
+ See also
+ <seealso marker="#rand_seed_alg-1">rand_seed_alg/1</seealso>.
+ </p>
+ <p>
+ To get a long period the Xoroshiro928 generator from the
+ <seealso marker="stdlib:rand">rand</seealso>
+ module is used as a counter (with period 2^928 - 1)
+ and the generator states are scrambled through AES
+ to create 58-bit pseudo random values.
+ </p>
+ <p>
+ The result should be statistically completely unpredictable
+ random values, since the scrambling is cryptographically strong
+ and the period is ridiculously long. But the generated numbers
+ are not to be regarded as cryptographically strong since
+ there is no re-keying schedule.
+ </p>
+ <list type="bulleted">
+ <item>
+ <p>
+ If you need cryptographically strong random numbers use
+ <seealso marker="#rand_seed_alg_s-1">rand_seed_alg_s/1</seealso>
+ with <c>Alg =:= crypto</c> or <c>Alg =:= crypto_cache</c>.
+ </p>
+ </item>
+ <item>
+ <p>
+ If you need to be able to repeat the sequence use this function.
+ </p>
+ </item>
+ <item>
+ <p>
+ If you do not need the statistical quality of this function,
+ there are faster algorithms in the
+ <seealso marker="stdlib:rand">rand</seealso>
+ module.
+ </p>
+ </item>
+ </list>
+ <p>
+ Thanks to the used generator the state object supports the
+ <seealso marker="stdlib:rand#jump-0"><c>rand:jump/0,1</c></seealso>
+ function with distance 2^512.
+ </p>
+ <p>
+ Numbers are generated in batches and cached for speed reasons.
+ 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>
+ </desc>
+ </func>
+
+ <func>
<name name="stream_init" arity="2" since="OTP R16B01"/>
<fsummary></fsummary>
<desc>