refactor: deprecate secp256k1 native, transition to noscrypt library

1 files changed, 101 insertions, 0 deletions

diff --git a/lib/NVault.Crypto.Noscrypt/src/UnmanagedRandomSource.cs b/lib/NVault.Crypto.Noscrypt/src/UnmanagedRandomSource.cs
new file mode 100644
index 0000000..2986e33
--- /dev/null
+++ b/lib/NVault.Crypto.Noscrypt/src/UnmanagedRandomSource.cs
@@ -0,0 +1,101 @@
+// Copyright (C) 2024 Vaughn Nugent
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+using System;
+using System.Runtime.InteropServices;
+
+using VNLib.Utils;
+using VNLib.Utils.Native;
+using VNLib.Utils.Extensions;
+
+namespace NVault.Crypto.Noscrypt
+{
+
+    /// <summary>
+    /// A wrapper class for an unmanaged random source that conforms to the <see cref="IRandomSource"/> interface
+    /// </summary>
+    public class UnmanagedRandomSource : VnDisposeable, IRandomSource
+    {
+        public const string METHOD_NAME = "getRandomBytes";
+
+        unsafe delegate void UnmanagedRandomSourceDelegate(byte* buffer, int size);
+
+
+        private readonly bool OwnsHandle;
+        private readonly SafeLibraryHandle _library;
+        private readonly UnmanagedRandomSourceDelegate _getRandomBytes;
+
+        /// <summary>
+        /// Loads the unmanaged random source from the given library 
+        /// and attempts to get the random bytes method <see cref="METHOD_NAME"/>
+        /// </summary>
+        /// <param name="path"></param>
+        /// <param name="search"></param>
+        /// <returns>The wrapped library that conforms to the <see cref="IRandomSource"/></returns>
+        public static UnmanagedRandomSource LoadLibrary(string path, DllImportSearchPath search)
+        {
+            //Try to load the library
+            SafeLibraryHandle lib = SafeLibraryHandle.LoadLibrary(path, search);
+            try
+            {
+                return new UnmanagedRandomSource(lib, true);
+            }
+            catch
+            {
+                //release lib
+                lib.Dispose();
+                throw;
+            }
+        }
+
+        /// <summary>
+        /// Creates the unmanaged random source from the given library
+        /// </summary>
+        /// <param name="lib">The library handle to wrap</param>
+        /// <exception cref="ObjectDisposedException"></exception>
+        /// <exception cref="EntryPointNotFoundException"></exception>
+        public UnmanagedRandomSource(SafeLibraryHandle lib, bool ownsHandle)
+        {
+            lib.ThrowIfClosed();
+
+            _library = lib;
+
+            //get the method delegate
+            _getRandomBytes = lib.DangerousGetFunction<UnmanagedRandomSourceDelegate>(METHOD_NAME);
+
+            OwnsHandle = ownsHandle;
+        }
+
+        public unsafe void GetRandomBytes(Span<byte> buffer)
+        {
+            _library.ThrowIfClosed();
+
+            //Fix buffer and call unmanaged method
+            fixed (byte* ptr = &MemoryMarshal.GetReference(buffer))
+            {
+                _getRandomBytes(ptr, buffer.Length);
+            }
+        }
+
+        ///<inheritdoc/>
+        protected override void Free()
+        {
+            if (OwnsHandle)
+            {
+                _library.Dispose();
+            }
+        }
+    }
+}
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