diff --git a/modules/openapi-generator/src/main/resources/csharp/HttpSigningConfiguration.mustache b/modules/openapi-generator/src/main/resources/csharp/HttpSigningConfiguration.mustache
index 04a0518a630a..913a483a9675 100644
--- a/modules/openapi-generator/src/main/resources/csharp/HttpSigningConfiguration.mustache
+++ b/modules/openapi-generator/src/main/resources/csharp/HttpSigningConfiguration.mustache
@@ -341,6 +341,10 @@ namespace {{packageName}}.Client
         /// <returns>ECDSA signature</returns>
         private string GetECDSASignature(byte[] dataToSign)
         {
+            {{#net60OrLater}}
+            if (!File.Exists(KeyFilePath))
+                throw new Exception("key file path does not exist.");
+
             var keyStr = KeyString;
             const string ecKeyHeader = "-----BEGIN EC PRIVATE KEY-----";
             const string ecKeyFooter = "-----END EC PRIVATE KEY-----";
@@ -348,7 +352,6 @@ namespace {{packageName}}.Client
             var keyBytes = System.Convert.FromBase64String(ecKeyBase64String);
             var ecdsa = ECDsa.Create();
 
-#if (NETCOREAPP3_0 || NETCOREAPP3_1 || NET5_0)
             var byteCount = 0;
             if (KeyPassPhrase != null)
             {
@@ -368,17 +371,17 @@ namespace {{packageName}}.Client
                 }
             }
             else
-            {
                 ecdsa.ImportPkcs8PrivateKey(keyBytes, out byteCount);
-            }
+
             var signedBytes = ecdsa.SignHash(dataToSign);
             var derBytes = ConvertToECDSAANS1Format(signedBytes);
             var signedString = System.Convert.ToBase64String(derBytes);
 
             return signedString;
-#else
+            {{/net60OrLater}}
+            {{^net60OrLater}}
             throw new Exception("ECDSA signing is supported only on NETCOREAPP3_0 and above");
-#endif
+            {{/net60OrLater}}
         }
 
         private byte[] ConvertToECDSAANS1Format(byte[] signedBytes)
diff --git a/samples/client/petstore/csharp/OpenAPIClient-ConditionalSerialization/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs b/samples/client/petstore/csharp/OpenAPIClient-ConditionalSerialization/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
index 2f04603b7f96..329284ff41d0 100644
--- a/samples/client/petstore/csharp/OpenAPIClient-ConditionalSerialization/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
+++ b/samples/client/petstore/csharp/OpenAPIClient-ConditionalSerialization/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
@@ -349,44 +349,7 @@ namespace Org.OpenAPITools.Client
         /// <returns>ECDSA signature</returns>
         private string GetECDSASignature(byte[] dataToSign)
         {
-            var keyStr = KeyString;
-            const string ecKeyHeader = "-----BEGIN EC PRIVATE KEY-----";
-            const string ecKeyFooter = "-----END EC PRIVATE KEY-----";
-            var ecKeyBase64String = keyStr.Replace(ecKeyHeader, "").Replace(ecKeyFooter, "").Trim();
-            var keyBytes = System.Convert.FromBase64String(ecKeyBase64String);
-            var ecdsa = ECDsa.Create();
-
-#if (NETCOREAPP3_0 || NETCOREAPP3_1 || NET5_0)
-            var byteCount = 0;
-            if (KeyPassPhrase != null)
-            {
-                IntPtr unmanagedString = IntPtr.Zero;
-                try
-                {
-                    // convert secure string to byte array
-                    unmanagedString = Marshal.SecureStringToGlobalAllocUnicode(KeyPassPhrase);
-                    ecdsa.ImportEncryptedPkcs8PrivateKey(Encoding.UTF8.GetBytes(Marshal.PtrToStringUni(unmanagedString)), keyBytes, out byteCount);
-                }
-                finally
-                {
-                    if (unmanagedString != IntPtr.Zero)
-                    {
-                        Marshal.ZeroFreeBSTR(unmanagedString);
-                    }
-                }
-            }
-            else
-            {
-                ecdsa.ImportPkcs8PrivateKey(keyBytes, out byteCount);
-            }
-            var signedBytes = ecdsa.SignHash(dataToSign);
-            var derBytes = ConvertToECDSAANS1Format(signedBytes);
-            var signedString = System.Convert.ToBase64String(derBytes);
-
-            return signedString;
-#else
             throw new Exception("ECDSA signing is supported only on NETCOREAPP3_0 and above");
-#endif
         }
 
         private byte[] ConvertToECDSAANS1Format(byte[] signedBytes)
diff --git a/samples/client/petstore/csharp/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs b/samples/client/petstore/csharp/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
index 2f04603b7f96..329284ff41d0 100644
--- a/samples/client/petstore/csharp/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
+++ b/samples/client/petstore/csharp/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
@@ -349,44 +349,7 @@ namespace Org.OpenAPITools.Client
         /// <returns>ECDSA signature</returns>
         private string GetECDSASignature(byte[] dataToSign)
         {
-            var keyStr = KeyString;
-            const string ecKeyHeader = "-----BEGIN EC PRIVATE KEY-----";
-            const string ecKeyFooter = "-----END EC PRIVATE KEY-----";
-            var ecKeyBase64String = keyStr.Replace(ecKeyHeader, "").Replace(ecKeyFooter, "").Trim();
-            var keyBytes = System.Convert.FromBase64String(ecKeyBase64String);
-            var ecdsa = ECDsa.Create();
-
-#if (NETCOREAPP3_0 || NETCOREAPP3_1 || NET5_0)
-            var byteCount = 0;
-            if (KeyPassPhrase != null)
-            {
-                IntPtr unmanagedString = IntPtr.Zero;
-                try
-                {
-                    // convert secure string to byte array
-                    unmanagedString = Marshal.SecureStringToGlobalAllocUnicode(KeyPassPhrase);
-                    ecdsa.ImportEncryptedPkcs8PrivateKey(Encoding.UTF8.GetBytes(Marshal.PtrToStringUni(unmanagedString)), keyBytes, out byteCount);
-                }
-                finally
-                {
-                    if (unmanagedString != IntPtr.Zero)
-                    {
-                        Marshal.ZeroFreeBSTR(unmanagedString);
-                    }
-                }
-            }
-            else
-            {
-                ecdsa.ImportPkcs8PrivateKey(keyBytes, out byteCount);
-            }
-            var signedBytes = ecdsa.SignHash(dataToSign);
-            var derBytes = ConvertToECDSAANS1Format(signedBytes);
-            var signedString = System.Convert.ToBase64String(derBytes);
-
-            return signedString;
-#else
             throw new Exception("ECDSA signing is supported only on NETCOREAPP3_0 and above");
-#endif
         }
 
         private byte[] ConvertToECDSAANS1Format(byte[] signedBytes)
diff --git a/samples/client/petstore/csharp/OpenAPIClient-net47/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs b/samples/client/petstore/csharp/OpenAPIClient-net47/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
index 2f04603b7f96..329284ff41d0 100644
--- a/samples/client/petstore/csharp/OpenAPIClient-net47/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
+++ b/samples/client/petstore/csharp/OpenAPIClient-net47/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
@@ -349,44 +349,7 @@ namespace Org.OpenAPITools.Client
         /// <returns>ECDSA signature</returns>
         private string GetECDSASignature(byte[] dataToSign)
         {
-            var keyStr = KeyString;
-            const string ecKeyHeader = "-----BEGIN EC PRIVATE KEY-----";
-            const string ecKeyFooter = "-----END EC PRIVATE KEY-----";
-            var ecKeyBase64String = keyStr.Replace(ecKeyHeader, "").Replace(ecKeyFooter, "").Trim();
-            var keyBytes = System.Convert.FromBase64String(ecKeyBase64String);
-            var ecdsa = ECDsa.Create();
-
-#if (NETCOREAPP3_0 || NETCOREAPP3_1 || NET5_0)
-            var byteCount = 0;
-            if (KeyPassPhrase != null)
-            {
-                IntPtr unmanagedString = IntPtr.Zero;
-                try
-                {
-                    // convert secure string to byte array
-                    unmanagedString = Marshal.SecureStringToGlobalAllocUnicode(KeyPassPhrase);
-                    ecdsa.ImportEncryptedPkcs8PrivateKey(Encoding.UTF8.GetBytes(Marshal.PtrToStringUni(unmanagedString)), keyBytes, out byteCount);
-                }
-                finally
-                {
-                    if (unmanagedString != IntPtr.Zero)
-                    {
-                        Marshal.ZeroFreeBSTR(unmanagedString);
-                    }
-                }
-            }
-            else
-            {
-                ecdsa.ImportPkcs8PrivateKey(keyBytes, out byteCount);
-            }
-            var signedBytes = ecdsa.SignHash(dataToSign);
-            var derBytes = ConvertToECDSAANS1Format(signedBytes);
-            var signedString = System.Convert.ToBase64String(derBytes);
-
-            return signedString;
-#else
             throw new Exception("ECDSA signing is supported only on NETCOREAPP3_0 and above");
-#endif
         }
 
         private byte[] ConvertToECDSAANS1Format(byte[] signedBytes)
diff --git a/samples/client/petstore/csharp/OpenAPIClient-net48/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs b/samples/client/petstore/csharp/OpenAPIClient-net48/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
index 2f04603b7f96..329284ff41d0 100644
--- a/samples/client/petstore/csharp/OpenAPIClient-net48/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
+++ b/samples/client/petstore/csharp/OpenAPIClient-net48/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
@@ -349,44 +349,7 @@ namespace Org.OpenAPITools.Client
         /// <returns>ECDSA signature</returns>
         private string GetECDSASignature(byte[] dataToSign)
         {
-            var keyStr = KeyString;
-            const string ecKeyHeader = "-----BEGIN EC PRIVATE KEY-----";
-            const string ecKeyFooter = "-----END EC PRIVATE KEY-----";
-            var ecKeyBase64String = keyStr.Replace(ecKeyHeader, "").Replace(ecKeyFooter, "").Trim();
-            var keyBytes = System.Convert.FromBase64String(ecKeyBase64String);
-            var ecdsa = ECDsa.Create();
-
-#if (NETCOREAPP3_0 || NETCOREAPP3_1 || NET5_0)
-            var byteCount = 0;
-            if (KeyPassPhrase != null)
-            {
-                IntPtr unmanagedString = IntPtr.Zero;
-                try
-                {
-                    // convert secure string to byte array
-                    unmanagedString = Marshal.SecureStringToGlobalAllocUnicode(KeyPassPhrase);
-                    ecdsa.ImportEncryptedPkcs8PrivateKey(Encoding.UTF8.GetBytes(Marshal.PtrToStringUni(unmanagedString)), keyBytes, out byteCount);
-                }
-                finally
-                {
-                    if (unmanagedString != IntPtr.Zero)
-                    {
-                        Marshal.ZeroFreeBSTR(unmanagedString);
-                    }
-                }
-            }
-            else
-            {
-                ecdsa.ImportPkcs8PrivateKey(keyBytes, out byteCount);
-            }
-            var signedBytes = ecdsa.SignHash(dataToSign);
-            var derBytes = ConvertToECDSAANS1Format(signedBytes);
-            var signedString = System.Convert.ToBase64String(derBytes);
-
-            return signedString;
-#else
             throw new Exception("ECDSA signing is supported only on NETCOREAPP3_0 and above");
-#endif
         }
 
         private byte[] ConvertToECDSAANS1Format(byte[] signedBytes)
diff --git a/samples/client/petstore/csharp/OpenAPIClient-net5.0/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs b/samples/client/petstore/csharp/OpenAPIClient-net5.0/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
index e42e333d3751..f8c8de85abad 100644
--- a/samples/client/petstore/csharp/OpenAPIClient-net5.0/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
+++ b/samples/client/petstore/csharp/OpenAPIClient-net5.0/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
@@ -349,6 +349,9 @@ namespace Org.OpenAPITools.Client
         /// <returns>ECDSA signature</returns>
         private string GetECDSASignature(byte[] dataToSign)
         {
+            if (!File.Exists(KeyFilePath))
+                throw new Exception("key file path does not exist.");
+
             var keyStr = KeyString;
             const string ecKeyHeader = "-----BEGIN EC PRIVATE KEY-----";
             const string ecKeyFooter = "-----END EC PRIVATE KEY-----";
@@ -356,7 +359,6 @@ namespace Org.OpenAPITools.Client
             var keyBytes = System.Convert.FromBase64String(ecKeyBase64String);
             var ecdsa = ECDsa.Create();
 
-#if (NETCOREAPP3_0 || NETCOREAPP3_1 || NET5_0)
             var byteCount = 0;
             if (KeyPassPhrase != null)
             {
@@ -376,17 +378,13 @@ namespace Org.OpenAPITools.Client
                 }
             }
             else
-            {
                 ecdsa.ImportPkcs8PrivateKey(keyBytes, out byteCount);
-            }
+
             var signedBytes = ecdsa.SignHash(dataToSign);
             var derBytes = ConvertToECDSAANS1Format(signedBytes);
             var signedString = System.Convert.ToBase64String(derBytes);
 
             return signedString;
-#else
-            throw new Exception("ECDSA signing is supported only on NETCOREAPP3_0 and above");
-#endif
         }
 
         private byte[] ConvertToECDSAANS1Format(byte[] signedBytes)
diff --git a/samples/client/petstore/csharp/OpenAPIClient-unityWebRequest/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs b/samples/client/petstore/csharp/OpenAPIClient-unityWebRequest/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
index 2f04603b7f96..329284ff41d0 100644
--- a/samples/client/petstore/csharp/OpenAPIClient-unityWebRequest/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
+++ b/samples/client/petstore/csharp/OpenAPIClient-unityWebRequest/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
@@ -349,44 +349,7 @@ namespace Org.OpenAPITools.Client
         /// <returns>ECDSA signature</returns>
         private string GetECDSASignature(byte[] dataToSign)
         {
-            var keyStr = KeyString;
-            const string ecKeyHeader = "-----BEGIN EC PRIVATE KEY-----";
-            const string ecKeyFooter = "-----END EC PRIVATE KEY-----";
-            var ecKeyBase64String = keyStr.Replace(ecKeyHeader, "").Replace(ecKeyFooter, "").Trim();
-            var keyBytes = System.Convert.FromBase64String(ecKeyBase64String);
-            var ecdsa = ECDsa.Create();
-
-#if (NETCOREAPP3_0 || NETCOREAPP3_1 || NET5_0)
-            var byteCount = 0;
-            if (KeyPassPhrase != null)
-            {
-                IntPtr unmanagedString = IntPtr.Zero;
-                try
-                {
-                    // convert secure string to byte array
-                    unmanagedString = Marshal.SecureStringToGlobalAllocUnicode(KeyPassPhrase);
-                    ecdsa.ImportEncryptedPkcs8PrivateKey(Encoding.UTF8.GetBytes(Marshal.PtrToStringUni(unmanagedString)), keyBytes, out byteCount);
-                }
-                finally
-                {
-                    if (unmanagedString != IntPtr.Zero)
-                    {
-                        Marshal.ZeroFreeBSTR(unmanagedString);
-                    }
-                }
-            }
-            else
-            {
-                ecdsa.ImportPkcs8PrivateKey(keyBytes, out byteCount);
-            }
-            var signedBytes = ecdsa.SignHash(dataToSign);
-            var derBytes = ConvertToECDSAANS1Format(signedBytes);
-            var signedString = System.Convert.ToBase64String(derBytes);
-
-            return signedString;
-#else
             throw new Exception("ECDSA signing is supported only on NETCOREAPP3_0 and above");
-#endif
         }
 
         private byte[] ConvertToECDSAANS1Format(byte[] signedBytes)
diff --git a/samples/client/petstore/csharp/OpenAPIClient/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs b/samples/client/petstore/csharp/OpenAPIClient/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
index 2f04603b7f96..329284ff41d0 100644
--- a/samples/client/petstore/csharp/OpenAPIClient/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
+++ b/samples/client/petstore/csharp/OpenAPIClient/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
@@ -349,44 +349,7 @@ namespace Org.OpenAPITools.Client
         /// <returns>ECDSA signature</returns>
         private string GetECDSASignature(byte[] dataToSign)
         {
-            var keyStr = KeyString;
-            const string ecKeyHeader = "-----BEGIN EC PRIVATE KEY-----";
-            const string ecKeyFooter = "-----END EC PRIVATE KEY-----";
-            var ecKeyBase64String = keyStr.Replace(ecKeyHeader, "").Replace(ecKeyFooter, "").Trim();
-            var keyBytes = System.Convert.FromBase64String(ecKeyBase64String);
-            var ecdsa = ECDsa.Create();
-
-#if (NETCOREAPP3_0 || NETCOREAPP3_1 || NET5_0)
-            var byteCount = 0;
-            if (KeyPassPhrase != null)
-            {
-                IntPtr unmanagedString = IntPtr.Zero;
-                try
-                {
-                    // convert secure string to byte array
-                    unmanagedString = Marshal.SecureStringToGlobalAllocUnicode(KeyPassPhrase);
-                    ecdsa.ImportEncryptedPkcs8PrivateKey(Encoding.UTF8.GetBytes(Marshal.PtrToStringUni(unmanagedString)), keyBytes, out byteCount);
-                }
-                finally
-                {
-                    if (unmanagedString != IntPtr.Zero)
-                    {
-                        Marshal.ZeroFreeBSTR(unmanagedString);
-                    }
-                }
-            }
-            else
-            {
-                ecdsa.ImportPkcs8PrivateKey(keyBytes, out byteCount);
-            }
-            var signedBytes = ecdsa.SignHash(dataToSign);
-            var derBytes = ConvertToECDSAANS1Format(signedBytes);
-            var signedString = System.Convert.ToBase64String(derBytes);
-
-            return signedString;
-#else
             throw new Exception("ECDSA signing is supported only on NETCOREAPP3_0 and above");
-#endif
         }
 
         private byte[] ConvertToECDSAANS1Format(byte[] signedBytes)
diff --git a/samples/client/petstore/csharp/OpenAPIClientCore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs b/samples/client/petstore/csharp/OpenAPIClientCore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
index e42e333d3751..f8c8de85abad 100644
--- a/samples/client/petstore/csharp/OpenAPIClientCore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
+++ b/samples/client/petstore/csharp/OpenAPIClientCore/src/Org.OpenAPITools/Client/HttpSigningConfiguration.cs
@@ -349,6 +349,9 @@ namespace Org.OpenAPITools.Client
         /// <returns>ECDSA signature</returns>
         private string GetECDSASignature(byte[] dataToSign)
         {
+            if (!File.Exists(KeyFilePath))
+                throw new Exception("key file path does not exist.");
+
             var keyStr = KeyString;
             const string ecKeyHeader = "-----BEGIN EC PRIVATE KEY-----";
             const string ecKeyFooter = "-----END EC PRIVATE KEY-----";
@@ -356,7 +359,6 @@ namespace Org.OpenAPITools.Client
             var keyBytes = System.Convert.FromBase64String(ecKeyBase64String);
             var ecdsa = ECDsa.Create();
 
-#if (NETCOREAPP3_0 || NETCOREAPP3_1 || NET5_0)
             var byteCount = 0;
             if (KeyPassPhrase != null)
             {
@@ -376,17 +378,13 @@ namespace Org.OpenAPITools.Client
                 }
             }
             else
-            {
                 ecdsa.ImportPkcs8PrivateKey(keyBytes, out byteCount);
-            }
+
             var signedBytes = ecdsa.SignHash(dataToSign);
             var derBytes = ConvertToECDSAANS1Format(signedBytes);
             var signedString = System.Convert.ToBase64String(derBytes);
 
             return signedString;
-#else
-            throw new Exception("ECDSA signing is supported only on NETCOREAPP3_0 and above");
-#endif
         }
 
         private byte[] ConvertToECDSAANS1Format(byte[] signedBytes)