Implement PlatformEntropySource for macOS, Microsoft Windows, NetBSD, OpenBSD, Solaris

dub.json

@@ -28,5 +28,6 @@
 			"lflags": ["arch/tanya.a"],
 			"versions": ["TanyaNative"]
 		}
-	]
+	],
+	"libs-windows": ["advapi32"]
 }

source/tanya/math/random.d

@@ -94,6 +94,27 @@ abstract class EntropySource
     Nullable!ubyte poll(out ubyte[maxGather] output) @nogc;
 }
 
+version (CRuntime_Bionic)
+{
+    version = SecureARC4Random;
+}
+else version (OSX)
+{
+    version = SecureARC4Random;
+}
+else version (OpenBSD)
+{
+    version = SecureARC4Random;
+}
+else version (NetBSD)
+{
+    version = SecureARC4Random;
+}
+else version (Solaris)
+{
+    version = SecureARC4Random;
+}
+
 version (linux)
 {
     extern (C) long syscall(long number, ...) nothrow @system @nogc;
@@ -160,6 +181,173 @@ version (linux)
         }
     }
 }
+else version (SecureARC4Random)
+{
+    private extern (C) void arc4random_buf(scope void* buf, size_t nbytes) nothrow @nogc @system;
+
+    /**
+     * Uses arc4random_buf.
+     */
+    class PlatformEntropySource : EntropySource
+    {
+        /**
+         * Returns: Minimum bytes required from the entropy source.
+         */
+        override @property ubyte threshold() const pure nothrow @safe @nogc
+        {
+            return 32;
+        }
+
+        /**
+         * Returns: Whether this entropy source is strong.
+         */
+        override @property bool strong() const pure nothrow @safe @nogc
+        {
+            return true;
+        }
+
+        /**
+         * Poll the entropy source.
+         *
+         * Params:
+         *  output = Buffer to save the generate random sequence (the method will
+         *           to fill the buffer).
+         *
+         * Returns: Number of bytes that were copied to the $(D_PARAM output)
+         *          or $(D_PSYMBOL Nullable!ubyte.init) on error.
+         */
+        override Nullable!ubyte poll(out ubyte[maxGather] output) nothrow @nogc @safe
+        {
+            (() @trusted => arc4random_buf(output.ptr, output.length))();
+            return Nullable!ubyte(cast(ubyte) (output.length));
+        }
+    }
+
+    @nogc @system unittest
+    {
+        auto entropy = defaultAllocator.make!Entropy();
+        ubyte[blockSize] output;
+        output = entropy.random;
+
+        defaultAllocator.dispose(entropy);
+    }
+}
+else version (Windows)
+{
+    import core.sys.windows.basetsd : ULONG_PTR;
+    import core.sys.windows.windef : BOOL, DWORD, PBYTE;
+    import core.sys.windows.winnt : LPCSTR, LPCWSTR;
+    import core.sys.windows.wincrypt;
+    private extern(Windows) @nogc nothrow
+    {
+        BOOL CryptGenRandom(HCRYPTPROV, DWORD, PBYTE);
+        BOOL CryptAcquireContextA(HCRYPTPROV*, LPCSTR, LPCSTR, DWORD, DWORD);
+        BOOL CryptAcquireContextW(HCRYPTPROV*, LPCWSTR, LPCWSTR, DWORD, DWORD);
+        BOOL CryptReleaseContext(HCRYPTPROV, ULONG_PTR);
+    }
+
+    private bool initCryptGenRandom(scope ref HCRYPTPROV hProvider) @nogc nothrow @trusted
+    {
+        import core.sys.windows.winbase : GetLastError;
+        import core.sys.windows.winerror : NTE_BAD_KEYSET;
+
+        // https://msdn.microsoft.com/en-us/library/windows/desktop/aa379886(v=vs.85).aspx
+        // For performance reasons, we recommend that you set the pszContainer
+        // parameter to NULL and the dwFlags parameter to CRYPT_VERIFYCONTEXT
+        // in all situations where you do not require a persisted key.
+        // CRYPT_SILENT is intended for use with applications for which the UI cannot be displayed by the CSP.
+        if (!CryptAcquireContextW(&hProvider, null, null, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT | CRYPT_SILENT))
+        {
+            if (GetLastError() == NTE_BAD_KEYSET)
+            {
+                // Attempt to create default container
+                if (!CryptAcquireContextA(&hProvider, null, null, PROV_RSA_FULL, CRYPT_NEWKEYSET | CRYPT_SILENT))
+                    return false;
+            }
+            else
+            {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    class PlatformEntropySource : EntropySource
+    {
+        private HCRYPTPROV hProvider;
+
+        /**
+         * Uses CryptGenRandom.
+         */
+        this() @nogc
+        {
+            if (!initCryptGenRandom(hProvider))
+            {
+                throw defaultAllocator.make!EntropyException("CryptAcquireContextW failed.");
+            }
+            assert(hProvider > 0, "hProvider not properly initialized.");
+        }
+
+        ~this() @nogc nothrow @safe
+        {
+            if (hProvider > 0)
+            {
+                (() @trusted => CryptReleaseContext(hProvider, 0))();
+            }
+        }
+
+        /**
+         * Returns: Minimum bytes required from the entropy source.
+         */
+        override @property ubyte threshold() const pure nothrow @safe @nogc
+        {
+            return 32;
+        }
+
+        /**
+         * Returns: Whether this entropy source is strong.
+         */
+        override @property bool strong() const pure nothrow @safe @nogc
+        {
+            return true;
+        }
+
+        /**
+         * Poll the entropy source.
+         *
+         * Params:
+         *  output = Buffer to save the generate random sequence (the method will
+         *           to fill the buffer).
+         *
+         * Returns: Number of bytes that were copied to the $(D_PARAM output)
+         *          or $(D_PSYMBOL Nullable!ubyte.init) on error.
+         */
+        override Nullable!ubyte poll(out ubyte[maxGather] output) @nogc nothrow @safe
+        in
+        {
+            assert(hProvider > 0, "hProvider not properly initialized.");
+        }
+        do
+        {
+            Nullable!ubyte ret;
+            if ((() @trusted => CryptGenRandom(hProvider, output.length, cast(PBYTE) output.ptr))())
+            {
+                ret = cast(ubyte) (output.length);
+            }
+            return ret;
+        }
+    }
+
+    @nogc @system unittest
+    {
+        auto entropy = defaultAllocator.make!Entropy();
+        ubyte[blockSize] output;
+        output = entropy.random;
+
+        defaultAllocator.dispose(entropy);
+    }
+}
 
 /**
  * Pseudorandom number generator.
@@ -180,8 +368,6 @@ class Entropy
 
     private ubyte sourceCount_;
 
-    private shared Allocator allocator;
-
     /// Entropy accumulator.
     protected SHA!(maxGather * 8, 512) accumulator;
 
@@ -202,7 +388,7 @@ class Entropy
     {
         allocator.resize(sources, maxSources);
 
-        version (linux)
+        static if (is(PlatformEntropySource))
         {
             this ~= allocator.make!PlatformEntropySource;
         }
@@ -289,7 +475,7 @@ class Entropy
 
         if (!haveStrong)
         {
-            throw allocator.make!EntropyException("No strong entropy source defined.");
+            throw defaultAllocator.make!EntropyException("No strong entropy source defined.");
         }
 
         output = accumulator.finish();