+hazel-networking

1 files changed, 86 insertions, 0 deletions

diff --git a/Tools/Hazel-Networking/Hazel/Crypto/Sha256Stream.cs b/Tools/Hazel-Networking/Hazel/Crypto/Sha256Stream.cs
new file mode 100644
index 0000000..1903693
--- /dev/null
+++ b/Tools/Hazel-Networking/Hazel/Crypto/Sha256Stream.cs
@@ -0,0 +1,86 @@
+using System;
+using System.Security.Cryptography;
+
+namespace Hazel.Crypto
+{
+    /// <summary>
+    /// Streams data into a SHA256 digest
+    /// </summary>
+    public class Sha256Stream : IDisposable
+    {
+        /// <summary>
+        /// Size of the SHA256 digest in bytes
+        /// </summary>
+        public const int DigestSize = 32;
+
+        private SHA256 hash = SHA256.Create();
+        private bool isHashFinished = false;
+
+        struct EmptyArray
+        {
+            public static readonly byte[] Value = new byte[0];
+        }
+
+        /// <summary>
+        /// Create a new instance of a SHA256 stream
+        /// </summary>
+        public Sha256Stream()
+        {
+        }
+
+        /// <summary>
+        /// Release resources associated with the stream
+        /// </summary>
+        public void Dispose()
+        {
+            this.hash?.Dispose();
+            this.hash = null;
+
+            GC.SuppressFinalize(this);
+        }
+
+        /// <summary>
+        /// Reset the stream to its initial state
+        /// </summary>
+        public void Reset()
+        {
+            this.hash?.Dispose();
+            this.hash = SHA256.Create();
+            this.isHashFinished = false;
+        }
+
+        /// <summary>
+        /// Add data to the stream
+        /// </summary>
+        public void AddData(ByteSpan data)
+        {
+            while (data.Length > 0)
+            {
+                int offset = this.hash.TransformBlock(data.GetUnderlyingArray(), data.Offset, data.Length, null, 0);
+                data = data.Slice(offset);
+            }
+        }
+
+        /// <summary>
+        /// Calculate the final hash of the stream data
+        /// </summary>
+        /// <param name="output">
+        /// Target span to which the hash will be written
+        /// </param>
+        public void CopyOrCalculateFinalHash(ByteSpan output)
+        {
+            if (output.Length != DigestSize)
+            {
+                throw new ArgumentException($"Expected a span of {DigestSize} bytes. Got a span of {output.Length} bytes", nameof(output));
+            }
+
+            if (this.isHashFinished == false)
+            {
+                this.hash.TransformFinalBlock(EmptyArray.Value, 0, 0);
+                this.isHashFinished = true;
+            }
+
+            new ByteSpan(this.hash.Hash).CopyTo(output);
+        }
+    }
+}