Merge pull request #975 from fadushin/doc-crypto-strong_rand_bytes

Document `crypto:strong_rand_bytes/1`

These changes are made under both the "Apache 2.0" and the "GNU Lesser General
Public License 2.1 or later" license terms (dual license).

SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later

doc/src/programmers-guide.md

@@ -641,10 +641,10 @@ Use `atomvm:random/0` to generate a random unsigned 32-bit integer in the range
     %% erlang
     RandomInteger = atomvm:random().
 
-Use `atomvm:random_bytes/1` to return a randomly populated binary of a specified size:
+Use `crypto:strong_rand_bytes/1` to return a randomly populated binary of a specified size:
 
     %% erlang
-    RandomBinary = erlang:random_bytes(32).
+    RandomBinary = crypto:strong_rand_bytes(32).
 
 Use `base64:encode/1` and `base64:decode/1` to encode to and decode from Base64 format.  The input value to these functions may be a binary or string.  The output value from these functions is an Erlang binary.
 

libs/estdlib/src/crypto.erl

@@ -22,7 +22,8 @@
 -export([
     hash/2,
     crypto_one_time/4,
-    crypto_one_time/5
+    crypto_one_time/5,
+    strong_rand_bytes/1
 ]).
 
 -type hash_algorithm() :: md5 | sha | sha224 | sha256 | sha384 | sha512.
@@ -100,3 +101,14 @@ crypto_one_time(_Cipher, _Key, _Data, _FlagOrOptions) ->
 ) -> binary().
 crypto_one_time(_Cipher, _Key, _IV, _Data, _FlagOrOptions) ->
     erlang:nif_error(undefined).
+
+%%-----------------------------------------------------------------------------
+%% @param   N desired length of cryptographically secure random data
+%% @returns Returns Cryptographically secure random data of length `N'
+%% @doc     Generate N cryptographically secure random octets
+%%          and return the result in a binary.
+%% @end
+%%-----------------------------------------------------------------------------
+-spec strong_rand_bytes(N :: non_neg_integer()) -> binary().
+strong_rand_bytes(_N) ->
+    erlang:nif_error(undefined).