diff --git a/SMBLibrary.Tests/NTLM/NTLMSigningTests.cs b/SMBLibrary.Tests/NTLM/NTLMSigningTests.cs
index 1ab6d03..eaf37dd 100644
--- a/SMBLibrary.Tests/NTLM/NTLMSigningTests.cs
+++ b/SMBLibrary.Tests/NTLM/NTLMSigningTests.cs
@@ -4,8 +4,6 @@
  * the GNU Lesser Public License as published by the Free Software Foundation,
  * either version 3 of the License, or (at your option) any later version.
  */
-using System;
-using System.Collections.Generic;
 using System.Security.Cryptography;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using SMBLibrary.Authentication.NTLM;
@@ -183,6 +181,34 @@ namespace SMBLibrary.Tests
             Assert.IsTrue(isMicValid);
         }
 
+        [TestMethod]
+        public void Test_ComputeClientSignKey()
+        {
+            // Arrange
+            byte[] exportedSessionKey = new byte[] { 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55 };
+            byte[] expected = new byte[] { 0x47, 0x88, 0xdc, 0x86, 0x1b, 0x47, 0x82, 0xf3, 0x5d, 0x43, 0xfd, 0x98, 0xfe, 0x1a, 0x2d, 0x39 };
+
+            // Act
+            byte[] signKey = NTLMCryptography.ComputeClientSignKey(exportedSessionKey);
+
+            // Assert
+            Assert.IsTrue(ByteUtils.AreByteArraysEqual(expected, signKey));
+        }
+
+        [TestMethod]
+        public void Test_ComputeClientSealKey()
+        {
+            // Arrange
+            byte[] exportedSessionKey = new byte[] { 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55, 0x55 };
+            byte[] expected = new byte[] { 0x59, 0xf6, 0x00, 0x97, 0x3c, 0xc4, 0x96, 0x0a, 0x25, 0x48, 0x0a, 0x7c, 0x19, 0x6e, 0x4c, 0x58 };
+
+            // Act
+            byte[] sealKey = NTLMCryptography.ComputeClientSealKey(exportedSessionKey);
+
+            // Assert
+            Assert.IsTrue(ByteUtils.AreByteArraysEqual(expected, sealKey));
+        }
+
         private static byte[] GetExportedSessionKey(byte[] sessionBaseKey, AuthenticateMessage message, byte[] serverChallenge, byte[] lmowf)
         {
             byte[] keyExchangeKey;
diff --git a/SMBLibrary/Authentication/NTLM/Helpers/NTLMCryptography.cs b/SMBLibrary/Authentication/NTLM/Helpers/NTLMCryptography.cs
index ec7c8c8..d0da43f 100644
--- a/SMBLibrary/Authentication/NTLM/Helpers/NTLMCryptography.cs
+++ b/SMBLibrary/Authentication/NTLM/Helpers/NTLMCryptography.cs
@@ -273,5 +273,61 @@ namespace SMBLibrary.Authentication.NTLM
 
             return ByteUtils.AreByteArraysEqual(mic, expectedMic);
         }
+
+        public static byte[] ComputeClientSignKey(byte[] exportedSessionKey)
+        {
+            return ComputeSignKey(exportedSessionKey, true);
+        }
+
+        public static byte[] ComputeServerSignKey(byte[] exportedSessionKey)
+        {
+            return ComputeSignKey(exportedSessionKey, false);
+        }
+
+        private static byte[] ComputeSignKey(byte[] exportedSessionKey, bool isClient)
+        {
+            // https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-nlmp/524cdccb-563e-4793-92b0-7bc321fce096
+            string str;
+            if (isClient)
+            {
+                str = "session key to client-to-server signing key magic constant";
+            }
+            else
+            {
+                str = "session key to server-to-client signing key magic constant";
+            }
+            byte[] encodedString = Encoding.GetEncoding(28591).GetBytes(str);
+            byte[] nullTerminatedEncodedString = ByteUtils.Concatenate(encodedString, new byte[1]);
+            byte[] concatendated = ByteUtils.Concatenate(exportedSessionKey, nullTerminatedEncodedString);
+            return MD5.Create().ComputeHash(concatendated);
+        }
+
+        public static byte[] ComputeClientSealKey(byte[] exportedSessionKey)
+        {
+            return ComputeSealKey(exportedSessionKey, true);
+        }
+
+        public static byte[] ComputeServerSealKey(byte[] exportedSessionKey)
+        {
+            return ComputeSealKey(exportedSessionKey, false);
+        }
+
+        private static byte[] ComputeSealKey(byte[] exportedSessionKey, bool isClient)
+        {
+            // https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-nlmp/524cdccb-563e-4793-92b0-7bc321fce096
+            string str;
+            if (isClient)
+            {
+                str = "session key to client-to-server sealing key magic constant";
+            }
+            else
+            {
+                str = "session key to server-to-client sealing key magic constant";
+            }
+            byte[] encodedString = Encoding.GetEncoding(28591).GetBytes(str);
+            byte[] nullTerminatedEncodedString = ByteUtils.Concatenate(encodedString, new byte[1]);
+            byte[] concatendated = ByteUtils.Concatenate(exportedSessionKey, nullTerminatedEncodedString);
+            return MD5.Create().ComputeHash(concatendated);
+        }
     }
 }