SHA256 in SQL Server using CRL

1. Create C# HashProc class, compile to HashProc.dll

using System;

public class HashProc
{
 [Microsoft.SqlServer.Server.SqlFunction(IsDeterministic = true, DataAccess = Microsoft.SqlServer.Server.DataAccessKind.None)]
 public static void SHA256(string inputStr, out string outputStr)
 {
  using (System.Security.Cryptography.SHA256Managed SHA256Crypto = new System.Security.Cryptography.SHA256Managed())
  {
   byte[] input = System.Text.Encoding.UTF8.GetBytes(inputStr);
   input = SHA256Crypto.ComputeHash(input);
   System.Text.StringBuilder output = new System.Text.StringBuilder();
   foreach (byte b in input)
   {
    output.Append(b.ToString("x2", System.Globalization.CultureInfo.InvariantCulture).ToUpperInvariant());
   }

   outputStr = output.ToString();
  }
 }
}

2. Enable CLR in SQL server

sp_configure 'show advanced options', 1;
GO
RECONFIGURE;
GO
sp_configure 'clr enabled', 1;
GO
RECONFIGURE;
GO

3. Register HashProc.dll into SQL server as a assembly

CREATE ASSEMBLY hashproc from 'C:\path\to\HashProc.dll' WITH PERMISSION_SET = SAFE;
GO

4. Create stored procedure to call the assembly hashproc

CREATE PROCEDURE sp_hash
@inputStr nvarchar(250),
@outputStr nvarchar(250) OUT
AS
EXTERNAL NAME hashproc.HashProc.SHA256;
GO

5. Call the stored procedure

DECLARE @outputStr nvarchar(250)
EXEC [dbo].[sp_hash]
  @inputStr = N'Test',
  @outputStr = @outputStr OUTPUT
SELECT @outputStr as N'@outputStr'
GO

Note: Confirm your SQL server CLR version supported using

select * from sys.dm_clr_properties;

That's all. You can change the HashProc class to using some more cryptography as SHA384 or SHA512 etc.