1 files changed, 185 insertions, 0 deletions
diff --git a/wrappers/dotnet/VNLib.Utils.Cryptography.Noscrypt/src/NCKeyUtil.cs b/wrappers/dotnet/VNLib.Utils.Cryptography.Noscrypt/src/NCKeyUtil.cs
new file mode 100644
index 0000000..50e1c9a
--- /dev/null
+++ b/wrappers/dotnet/VNLib.Utils.Cryptography.Noscrypt/src/NCKeyUtil.cs
@@ -0,0 +1,185 @@
+// 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 System.Runtime.CompilerServices;
+
+using VNLib.Utils.Extensions;
+using VNLib.Utils.Cryptography.Noscrypt.@internal;
+using static VNLib.Utils.Cryptography.Noscrypt.NoscryptLibrary;
+
+using NCResult = System.Int64;
+
+namespace VNLib.Utils.Cryptography.Noscrypt
+{
+    /// <summary>
+    /// Contains utility methods for working with nostr keys
+    /// </summary>
+    public static unsafe class NCKeyUtil
+    {
+        /// <summary>
+        /// Gets a span of bytes from the current secret key 
+        /// structure
+        /// </summary>
+        /// <param name="key"></param>
+        /// <returns>The secret key data span</returns>
+        public unsafe static Span<byte> AsSpan(this ref NCSecretKey key)
+        {
+            //Safe to cast secret key to bytes, then we can make a span to its memory
+            ref byte asBytes = ref Unsafe.As<NCSecretKey, byte>(ref key);
+            return MemoryMarshal.CreateSpan(ref asBytes, sizeof(NCSecretKey));
+        }
+
+        /// <summary>
+        /// Gets a span of bytes from the current public key
+        /// structure
+        /// </summary>
+        /// <param name="key"></param>
+        /// <returns>The public key data as a data span</returns>
+        public unsafe static Span<byte> AsSpan(this ref NCPublicKey key)
+        {
+            //Safe to cast secret key to bytes, then we can make a span to its memory
+            ref byte asBytes = ref Unsafe.As<NCPublicKey, byte>(ref key);
+            return MemoryMarshal.CreateSpan(ref asBytes, sizeof(NCPublicKey));
+        }
+
+        /// <summary>
+        /// Casts a span of bytes to a secret key reference. Note that
+        /// the new structure reference will point to the same memory
+        /// as the span.
+        /// </summary>
+        /// <param name="span">The secret key data</param>
+        /// <returns>A mutable secret key reference</returns>
+        /// <exception cref="ArgumentOutOfRangeException"></exception>
+        public unsafe static ref NCSecretKey AsSecretKey(Span<byte> span)
+        {
+            ArgumentOutOfRangeException.ThrowIfLessThan(span.Length, sizeof(NCSecretKey), nameof(span));
+
+            ref byte asBytes = ref MemoryMarshal.GetReference(span);
+            return ref Unsafe.As<byte, NCSecretKey>(ref asBytes);
+        }
+
+        /// <summary>
+        /// Casts a span of bytes to a public key reference. Note that
+        /// the new structure reference will point to the same memory
+        /// as the span.
+        /// </summary>
+        /// <param name="span">The public key data span</param>
+        /// <returns>A mutable reference to the public key structure</returns>
+        /// <exception cref="ArgumentOutOfRangeException"></exception>
+        public unsafe static ref NCPublicKey AsPublicKey(Span<byte> span)
+        {
+            ArgumentOutOfRangeException.ThrowIfLessThan(span.Length, sizeof(NCPublicKey), nameof(span));
+
+            ref byte asBytes = ref MemoryMarshal.GetReference(span);
+            return ref Unsafe.As<byte, NCPublicKey>(ref asBytes);
+        }
+
+        /// <summary>
+        /// Casts a read-only span of bytes to a secret key reference. Note that
+        /// the new structure reference will point to the same memory as the span.
+        /// </summary>
+        /// <param name="span">The secret key data span</param>
+        /// <returns>A readonly refernce to the secret key structure</returns>
+        /// <exception cref="ArgumentOutOfRangeException"></exception>
+        public unsafe static ref readonly NCSecretKey AsSecretKey(ReadOnlySpan<byte> span)
+        {
+            ArgumentOutOfRangeException.ThrowIfLessThan(span.Length, sizeof(NCSecretKey), nameof(span));
+
+            ref byte asBytes = ref MemoryMarshal.GetReference(span);
+            return ref Unsafe.As<byte, NCSecretKey>(ref asBytes);
+        }
+
+        /// <summary>
+        /// Casts a read-only span of bytes to a public key reference. Note that
+        /// the new structure reference will point to the same memory as the span.
+        /// </summary>
+        /// <param name="span">The public key data span</param>
+        /// <returns>A readonly reference to the public key structure</returns>
+        /// <exception cref="ArgumentOutOfRangeException"></exception>
+        public unsafe static ref readonly NCPublicKey AsPublicKey(ReadOnlySpan<byte> span)
+        {
+            ArgumentOutOfRangeException.ThrowIfLessThan(span.Length, sizeof(NCPublicKey), nameof(span));
+
+            ref byte asBytes = ref MemoryMarshal.GetReference(span);
+            return ref Unsafe.As<byte, NCPublicKey>(ref asBytes);
+        }
+
+        /// <summary>
+        /// Gets a nostr public key from a secret key.
+        /// </summary>
+        /// <param name="secretKey">A reference to the secret key to get the public key from</param>
+        /// <param name="publicKey">A reference to the public key structure to write the recovered key to</param>
+        /// <exception cref="ArgumentException"></exception>
+        /// <exception cref="ArgumentNullException"></exception>
+        public static void GetPublicKey(
+            NCContext context,
+            ref readonly NCSecretKey secretKey,
+            ref NCPublicKey publicKey
+        )
+        {
+            Check(context);
+
+            fixed (NCSecretKey* pSecKey = &secretKey)
+            fixed (NCPublicKey* pPubKey = &publicKey)
+            {
+                NCResult result = GetTable(context).NCGetPublicKey(
+                    context.DangerousGetHandle(),
+                    pSecKey,
+                    pPubKey
+                );
+
+                NCUtil.CheckResult<FunctionTable.NCGetPublicKeyDelegate>(result, raiseOnFailure: true);
+            }
+        }
+
+        /// <summary>
+        /// Validates a secret key is in a valid format. 
+        /// </summary>
+        /// <param name="secretKey">A readonly reference to key structure to validate</param>
+        /// <returns>True if the key is consiered valid against the secp256k1 curve</returns>
+        /// <exception cref="ArgumentException"></exception>
+        /// <exception cref="ArgumentNullException"></exception>
+        public static bool ValidateSecretKey(
+            NCContext context,
+            ref readonly NCSecretKey secretKey
+        )
+        {
+            Check(context);
+
+            fixed (NCSecretKey* pSecKey = &secretKey)
+            {
+                NCResult result = GetTable(context).NCValidateSecretKey(
+                    context.DangerousGetHandle(),
+                    pSecKey
+                );
+
+                NCUtil.CheckResult<FunctionTable.NCValidateSecretKeyDelegate>(result, raiseOnFailure: false);
+
+                return result == NC_SUCCESS;
+            }
+        }
+
+        private static void Check(NCContext? context)
+        {
+            ArgumentNullException.ThrowIfNull(context);
+            context.ThrowIfClosed();
+        }
+
+        private static ref readonly FunctionTable GetTable(NCContext ctx)
+            => ref ctx.Library.Functions;
+    }
+}