add missing secret key verification

4 files changed, 38 insertions, 4 deletions

diff --git a/back-end/libs/NVault.Crypto.Secp256k1/src/ContextExtensions.cs b/back-end/libs/NVault.Crypto.Secp256k1/src/ContextExtensions.cs
index b0e8695..a89fce8 100644
--- a/back-end/libs/NVault.Crypto.Secp256k1/src/ContextExtensions.cs
+++ b/back-end/libs/NVault.Crypto.Secp256k1/src/ContextExtensions.cs
@@ -15,6 +15,7 @@
 
 using System;
 using System.Security.Cryptography;
+using System.Runtime.InteropServices;
 
 using VNLib.Hashing;
 using VNLib.Utils;
@@ -89,7 +90,8 @@ namespace NVault.Crypto.Secp256k1
 
             try
             {
-                fixed (byte* sigPtr = signature, digestPtr = digest)
+                fixed (byte* sigPtr = &MemoryMarshal.GetReference(signature), 
+                            digestPtr = &MemoryMarshal.GetReference(digest))
                 {
                     //Sign the message hash and write the output to the signature buffer
                     if (context.Lib._signHash(context.Context, sigPtr, digestPtr, &keyPair, random) != 1)
@@ -153,7 +155,7 @@ namespace NVault.Crypto.Secp256k1
                     return ERRNO.E_FAIL;
                 }
 
-                fixed (byte* pubBuffer = pubKeyBuffer)
+                fixed (byte* pubBuffer = &MemoryMarshal.GetReference(pubKeyBuffer))
                 {
                     //Serialize the public key to the buffer as an X-only public key without leading status byte
                     if (context.Lib._serializeXonly(context.Context, pubBuffer, &xOnlyPubKey) != 1)
@@ -171,5 +173,28 @@ namespace NVault.Crypto.Secp256k1
             //PubKey length is constant
             return XOnlyPublicKeySize;
         }
+
+        /// <summary>
+        /// Verifies that a given secret key is valid using the current context
+        /// </summary>
+        /// <param name="context"></param>
+        /// <param name="secretKey">The secret key to verify</param>
+        /// <returns>A boolean value that indicates if the secret key is valid or not</returns>
+        /// <exception cref="CryptographicException"></exception>
+        public static bool VerifySecretKey(this in Secp256k1Context context, ReadOnlySpan<byte> secretKey)
+        {
+            if (secretKey.Length != SecretKeySize)
+            {
+                throw new CryptographicException($"Your secret key must be exactly {SecretKeySize} bytes long");
+            }
+
+            context.Lib.SafeLibHandle.ThrowIfClosed();
+
+            //Get sec key ref and verify
+            fixed(byte* ptr = &MemoryMarshal.GetReference(secretKey))
+            {
+                return context.Lib._secKeyVerify.Invoke(context.Context, ptr) == 1;
+            }
+        }
     }
 }
\ No newline at end of file
diff --git a/back-end/libs/NVault.Crypto.Secp256k1/src/LibSecp256k1.cs b/back-end/libs/NVault.Crypto.Secp256k1/src/LibSecp256k1.cs
index 2eea450..80d6eb8 100644
--- a/back-end/libs/NVault.Crypto.Secp256k1/src/LibSecp256k1.cs
+++ b/back-end/libs/NVault.Crypto.Secp256k1/src/LibSecp256k1.cs
@@ -72,6 +72,9 @@ namespace NVault.Crypto.Secp256k1
         [SafeMethodName("secp256k1_schnorrsig_sign32")]
         internal delegate int SignHash(IntPtr ctx, byte* sig64, byte* msg32, KeyPair* keypair, byte* aux_rand32);
 
+        [SafeMethodName("secp256k1_ec_seckey_verify")]
+        internal delegate int SecKeyVerify(IntPtr ctx, in byte* seckey);
+
         /// <summary>
         /// Loads the Secp256k1 library from the specified path and creates a wrapper class (loads methods from the library)
         /// </summary>
@@ -118,6 +121,7 @@ namespace NVault.Crypto.Secp256k1
         internal readonly KeypairXOnlyPub _createXonly;
         internal readonly XOnlyPubkeySerialize _serializeXonly;
         internal readonly SignHash _signHash;
+        internal readonly SecKeyVerify _secKeyVerify;
         private readonly IRandomSource _randomSource;
 
         /// <summary>
@@ -143,6 +147,7 @@ namespace NVault.Crypto.Secp256k1
             _createXonly = handle.DangerousGetMethod<KeypairXOnlyPub>();
             _serializeXonly = handle.DangerousGetMethod<XOnlyPubkeySerialize>();
             _signHash = handle.DangerousGetMethod<SignHash>();
+            _secKeyVerify = handle.DangerousGetMethod<SecKeyVerify>();
             
             //Store random source
             _randomSource = randomSource;
@@ -161,6 +166,9 @@ namespace NVault.Crypto.Secp256k1
 
         /// <summary>
         /// Generates a new secret key and writes it to the specified buffer. The buffer size must be exactly <see cref="SecretKeySize"/> bytes long
+        /// <para>
+        /// NOTE: You should verify this validity of the key against the library with a new <see cref="Secp256k1Context"/>
+        /// </para>
         /// </summary>
         /// <param name="buffer">The secret key buffer</param>
         /// <exception cref="ArgumentException"></exception>
diff --git a/back-end/libs/NVault.Crypto.Secp256k1/src/Secp256k1Context.cs b/back-end/libs/NVault.Crypto.Secp256k1/src/Secp256k1Context.cs
index 8aac0b8..67f1d9f 100644
--- a/back-end/libs/NVault.Crypto.Secp256k1/src/Secp256k1Context.cs
+++ b/back-end/libs/NVault.Crypto.Secp256k1/src/Secp256k1Context.cs
@@ -14,6 +14,7 @@
 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 using System;
+using System.Runtime.InteropServices;
 
 using VNLib.Utils.Extensions;
 using VNLib.Utils.Memory;
@@ -57,7 +58,7 @@ namespace NVault.Crypto.Secp256k1
         {
             Lib.SafeLibHandle.ThrowIfClosed();
 
-            fixed (byte* sk = secretKey)
+            fixed (byte* sk = &MemoryMarshal.GetReference(secretKey))
             {
                 //Create the keypair from the secret key
                 return Lib._createKeyPair(Context, keyPair, sk) == 1;
diff --git a/back-end/libs/NVault.Crypto.Secp256k1/src/UnmanagedRandomSource.cs b/back-end/libs/NVault.Crypto.Secp256k1/src/UnmanagedRandomSource.cs
index d4d9a06..d6ff5aa 100644
--- a/back-end/libs/NVault.Crypto.Secp256k1/src/UnmanagedRandomSource.cs
+++ b/back-end/libs/NVault.Crypto.Secp256k1/src/UnmanagedRandomSource.cs
@@ -83,7 +83,7 @@ namespace NVault.Crypto.Secp256k1
             _library.ThrowIfClosed();
 
             //Fix buffer and call unmanaged method
-            fixed(byte* ptr = buffer)
+            fixed(byte* ptr = &MemoryMarshal.GetReference(buffer))
             {
                 _getRandomBytes(ptr, buffer.Length);
             }