diff options
Diffstat (limited to 'lib/crypto')
| -rw-r--r-- | lib/crypto/doc/src/crypto.xml | 125 | ||||
| -rw-r--r-- | lib/crypto/doc/src/crypto_app.xml | 18 | ||||
| -rw-r--r-- | lib/crypto/src/crypto.app.src | 2 | ||||
| -rw-r--r-- | lib/crypto/src/crypto.erl | 47 |
4 files changed, 185 insertions, 7 deletions
diff --git a/lib/crypto/doc/src/crypto.xml b/lib/crypto/doc/src/crypto.xml index 36295c84cd..72351f1fe5 100644 --- a/lib/crypto/doc/src/crypto.xml +++ b/lib/crypto/doc/src/crypto.xml @@ -774,9 +774,16 @@ <seealso marker="stdlib:rand">random number generation</seealso>, in order to generate cryptographically strong random numbers (based on OpenSSL's <c>BN_rand_range</c>), - and saves it on process dictionary before returning it as well. + and saves it in the process dictionary before returning it as well. See also - <seealso marker="stdlib:rand#seed-1">rand:seed/1</seealso>. + <seealso marker="stdlib:rand#seed-1">rand:seed/1</seealso> and + <seealso marker="#rand_seed_s-0">rand_seed_s/0</seealso>. + </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> <p><em>Example</em></p> <pre> @@ -798,6 +805,120 @@ _FloatValue = rand:uniform(). % [0.0; 1.0[</pre> See also <seealso marker="stdlib:rand#seed_s-1">rand:seed_s/1</seealso>. </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 + to get a reproducable random sequence as from + the other + <seealso marker="stdlib:rand">rand</seealso> + functions, + since reproducability does not match cryptographically safe. + </p> + <p> + The only supported usage is to generate one distinct + random sequence from this start state. + </p> + </note> + </desc> + </func> + + <func> + <name>rand_seed_alg(Alg) -> rand:state()</name> + <fsummary>Strong random number generation plugin state</fsummary> + <type> + <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>, + in order to generate cryptographically strong random numbers. + 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>. + </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> + <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), +_IntegerValue = rand:uniform(42), % [1; 42] +_FloatValue = rand:uniform(). % [0.0; 1.0[</pre> + </desc> + </func> + + <func> + <name>rand_seed_alg_s(Alg) -> rand:state()</name> + <fsummary>Strong random number generation plugin state</fsummary> + <type> + <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>, + in order to generate cryptographically strongly random numbers. + See also + <seealso marker="stdlib:rand#seed_s-1">rand:seed_s/1</seealso>. + </p> + <p> + If <c>Alg</c> is <c>crypto</c> this function behaves exactly like + <seealso marker="#rand_seed_s-0">rand_seed_s/0</seealso>. + </p> + <p> + If <c>Alg</c> is <c>crypto_cache</c> this function + fetches random data with OpenSSL's <c>RAND_bytes</c> + and caches it for speed using an internal word size + of 56 bits that makes calculations fast on 64 bit machines. + </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> + <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 + to get a reproducable random sequence as from + the other + <seealso marker="stdlib:rand">rand</seealso> + functions, + since reproducability does not match cryptographically safe. + </p> + <p> + In fact since random data is cached some numbers may + get reproduced if you try, but this is unpredictable. + </p> + <p> + The only supported usage is to generate one distinct + random sequence from this start state. + </p> + </note> </desc> </func> 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> diff --git a/lib/crypto/src/crypto.app.src b/lib/crypto/src/crypto.app.src index 1d3f35e465..492aa10e51 100644 --- a/lib/crypto/src/crypto.app.src +++ b/lib/crypto/src/crypto.app.src @@ -24,7 +24,7 @@ crypto_ec_curves]}, {registered, []}, {applications, [kernel, stdlib]}, - {env, [{fips_mode, false}]}, + {env, [{fips_mode, false}, {rand_cache_size, 896}]}, {runtime_dependencies, ["erts-9.0","stdlib-3.4","kernel-5.3"]}]}. diff --git a/lib/crypto/src/crypto.erl b/lib/crypto/src/crypto.erl index 7510babdde..3e18756cf9 100644 --- a/lib/crypto/src/crypto.erl +++ b/lib/crypto/src/crypto.erl @@ -30,11 +30,12 @@ -export([hmac/3, hmac/4, hmac_init/2, hmac_update/2, hmac_final/1, hmac_final_n/2]). -export([cmac/3, cmac/4]). -export([exor/2, strong_rand_bytes/1, mod_pow/3]). --export([rand_seed/0]). --export([rand_seed_s/0]). +-export([rand_seed/0, rand_seed_alg/1]). +-export([rand_seed_s/0, rand_seed_alg_s/1]). -export([rand_plugin_next/1]). -export([rand_plugin_uniform/1]). -export([rand_plugin_uniform/2]). +-export([rand_cache_plugin_next/1]). -export([rand_uniform/2]). -export([block_encrypt/3, block_decrypt/3, block_encrypt/4, block_decrypt/4]). -export([next_iv/2, next_iv/3]). @@ -314,9 +315,17 @@ stream_decrypt(State, Data0) -> %% %% RAND - pseudo random numbers using RN_ and BN_ functions in crypto lib %% +-type rand_cache_seed() :: + nonempty_improper_list(non_neg_integer(), binary()). -spec strong_rand_bytes(non_neg_integer()) -> binary(). -spec rand_seed() -> rand:state(). -spec rand_seed_s() -> rand:state(). +-spec rand_seed_alg(Alg :: atom()) -> + {rand:alg_handler(), + atom() | rand_cache_seed()}. +-spec rand_seed_alg_s(Alg :: atom()) -> + {rand:alg_handler(), + atom() | rand_cache_seed()}. -spec rand_uniform(crypto_integer(), crypto_integer()) -> crypto_integer(). @@ -332,12 +341,36 @@ rand_seed() -> rand:seed(rand_seed_s()). rand_seed_s() -> + rand_seed_alg_s(?MODULE). + +rand_seed_alg(Alg) -> + rand:seed(rand_seed_alg_s(Alg)). + +-define(CRYPTO_CACHE_BITS, 56). +rand_seed_alg_s(?MODULE) -> {#{ type => ?MODULE, bits => 64, next => fun ?MODULE:rand_plugin_next/1, uniform => fun ?MODULE:rand_plugin_uniform/1, uniform_n => fun ?MODULE:rand_plugin_uniform/2}, - no_seed}. + no_seed}; +rand_seed_alg_s(crypto_cache) -> + CacheBits = ?CRYPTO_CACHE_BITS, + EnvCacheSize = + application:get_env( + crypto, rand_cache_size, CacheBits * 16), % Cache 16 * 8 words + Bytes = (CacheBits + 7) div 8, + CacheSize = + case ((EnvCacheSize + (Bytes - 1)) div Bytes) * Bytes of + Sz when is_integer(Sz), Bytes =< Sz -> + Sz; + _ -> + Bytes + end, + {#{ type => crypto_cache, + bits => CacheBits, + next => fun ?MODULE:rand_cache_plugin_next/1}, + {CacheBits, CacheSize, <<>>}}. rand_plugin_next(Seed) -> {bytes_to_integer(strong_rand_range(1 bsl 64)), Seed}. @@ -348,6 +381,12 @@ rand_plugin_uniform(State) -> rand_plugin_uniform(Max, State) -> {bytes_to_integer(strong_rand_range(Max)) + 1, State}. +rand_cache_plugin_next({CacheBits, CacheSize, <<>>}) -> + rand_cache_plugin_next( + {CacheBits, CacheSize, strong_rand_bytes(CacheSize)}); +rand_cache_plugin_next({CacheBits, CacheSize, Cache}) -> + <<I:CacheBits, NewCache/binary>> = Cache, + {I, {CacheBits, CacheSize, NewCache}}. strong_rand_range(Range) when is_integer(Range), Range > 0 -> BinRange = int_to_bin(Range), @@ -395,7 +434,7 @@ rand_uniform_nif(_From,_To) -> ?nif_stub. -spec rand_seed(binary()) -> ok. -rand_seed(Seed) -> +rand_seed(Seed) when is_binary(Seed) -> rand_seed_nif(Seed). rand_seed_nif(_Seed) -> ?nif_stub. |