diff options
Diffstat (limited to 'lib/crypto/doc/src')
| -rw-r--r-- | lib/crypto/doc/src/crypto.xml | 114 | ||||
| -rw-r--r-- | lib/crypto/doc/src/engine_keys.xml | 2 |
2 files changed, 105 insertions, 11 deletions
diff --git a/lib/crypto/doc/src/crypto.xml b/lib/crypto/doc/src/crypto.xml index 651b647e1c..b8ec41bea8 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> @@ -1002,7 +1001,7 @@ _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> @@ -1028,7 +1027,8 @@ _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>. @@ -1039,12 +1039,6 @@ _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), @@ -1054,6 +1048,34 @@ _FloatValue = rand:uniform(). % [0.0; 1.0[</pre> </func> <func> + <name>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>rand_seed_alg_s(Alg) -> rand:state()</name> <fsummary>Strong random number generation plugin state</fsummary> <type> @@ -1090,9 +1112,15 @@ _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> @@ -1112,6 +1140,72 @@ _FloatValue = rand:uniform(). % [0.0; 1.0[</pre> </func> <func> + <name>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"/> <fsummary></fsummary> <desc> diff --git a/lib/crypto/doc/src/engine_keys.xml b/lib/crypto/doc/src/engine_keys.xml index feeb353d1e..b28606fb4e 100644 --- a/lib/crypto/doc/src/engine_keys.xml +++ b/lib/crypto/doc/src/engine_keys.xml @@ -40,7 +40,7 @@ </p> <p> An engine could among other tasks provide a storage for - private or public keys. Such a storage could be made safer than the normal file system. Thoose techniques are not + private or public keys. Such a storage could be made safer than the normal file system. Those techniques are not described in this User's Guide. Here we concentrate on how to use private or public keys stored in such an engine. </p> |