SHA256 doesn't yield same result between C# and SQL Server when using Spanish words

Question

I am using SHA256 to get a hashed hexadecimal string. It works fine when using regular characters, however when a string to be hashed includes accents/diacritics, then I get a different result in C# and T-SQL. I would prefer to make the change on the SQL Server end.

• Example word that does match: bird
• Example word that does not match: MUÑOZ

C#

using (SHA256 sha2 = SHA256.Create())  
{
    var hash = sha2.ComputeHash(Encoding.UTF8.GetBytes(fullAddress));
    string hexString = string.Empty;

    for (int i = 0; i < hash.Length; i++)
    {
        hexString += hash[i].ToString("X2"); //Convert the byte to Hexadecimal representation, Notice that we use "X2" instead of "X"
    }

    sha2.Dispose();
    return hexString;
}

SQL

declare @fullAddress nvarchar(500)
set @fullAddress = 'MUÑOZ'
select CONVERT([varchar](256), HASHBYTES('SHA2_256', @fullAddress), 2) 

Answer 1

.NET, Windows and SQL Server use UTF16, not UTF8. The two snippets are hashing different bytes. When the same encoding is used, the hash strings are identical.

This :

using (var sha2 = System.Security.Cryptography.SHA256.Create())  
{
    var hash = sha2.ComputeHash(Encoding.Unicode.GetBytes("MUÑOZ"));
    {
        string hexString = string.Empty;

        for (int i = 0; i < hash.Length; i++)
        {
            hexString += hash[i].ToString("X2");
        }
        Console.WriteLine(hexString);        
    }    
}

Produces :

276DB000BF524070F106A2C413942159AB5EF2F5CA5A5B91AB2F3B6FA48EE1ED

Which is the same as SQL Server's hash string