From d58602adef3412b354fd521bbd4bda24a0b1a789 Mon Sep 17 00:00:00 2001
From: Lukas Larsson <lukas@erlang-solutions.com>
Date: Thu, 13 Feb 2014 18:14:10 +0100
Subject: crypto: Add rand_seed function

This function is needed on OSs that do not automatically
initialize the PRNG seed.
---
 lib/crypto/c_src/crypto.c     | 15 ++++++++++++++-
 lib/crypto/doc/src/crypto.xml | 15 +++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/lib/crypto/c_src/crypto.c b/lib/crypto/c_src/crypto.c
index 925ad0c091..bf8107d10b 100644
--- a/lib/crypto/c_src/crypto.c
+++ b/lib/crypto/c_src/crypto.c
@@ -254,6 +254,8 @@ static ERL_NIF_TERM ecdsa_sign_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM
 static ERL_NIF_TERM ecdsa_verify_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]);
 static ERL_NIF_TERM ecdh_compute_key_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]);
 
+static ERL_NIF_TERM rand_seed_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[]);
+
 
 /* helpers */
 static void init_algorithms_types(ErlNifEnv*);
@@ -381,7 +383,9 @@ static ErlNifFunc nif_funcs[] = {
     {"ec_key_generate", 1, ec_key_generate},
     {"ecdsa_sign_nif", 4, ecdsa_sign_nif},
     {"ecdsa_verify_nif", 5, ecdsa_verify_nif},
-    {"ecdh_compute_key_nif", 3, ecdh_compute_key_nif}
+    {"ecdh_compute_key_nif", 3, ecdh_compute_key_nif},
+
+    {"rand_seed_nif", 1, rand_seed_nif}
 };
 
 ERL_NIF_INIT(crypto,nif_funcs,load,NULL,upgrade,unload)
@@ -3374,6 +3378,15 @@ out_err:
 #endif
 }
 
+static ERL_NIF_TERM rand_seed_nif(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
+{
+    ErlNifBinary seed_bin;
+    if (!enif_inspect_binary(env, argv[0], &seed_bin))
+        return enif_make_badarg(env);
+    RAND_seed(seed_bin.data,seed_bin.size);
+    return atom_ok;
+}
+
 
 /* HMAC */
 
diff --git a/lib/crypto/doc/src/crypto.xml b/lib/crypto/doc/src/crypto.xml
index 40f829e704..952808d9db 100644
--- a/lib/crypto/doc/src/crypto.xml
+++ b/lib/crypto/doc/src/crypto.xml
@@ -552,6 +552,21 @@
       </desc>
     </func>
 
+    <func>
+      <name>rand_seed(Seed) -> ok</name>
+      <fsummary>Set the seed for random bytes generation</fsummary>
+      <type>
+        <v>Seed = binary()</v>
+      </type>
+      <desc>
+        <p>Set the seed for PRNG to the given binary. This calls the
+	RAND_seed function from openssl. Only use this if the system
+	you are running on does not have enough "randomness" built in.
+	Normally this is when <seealso marker="#strong_rand_bytes/1">
+	stong_rand_bytes/1</seealso> returns <c>low_entropy</c></p>
+      </desc>
+    </func>
+
      <func>
       <name>rand_uniform(Lo, Hi) -> N</name>
       <fsummary>Generate a random number</fsummary>
-- 
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