‘SHA256Managed’ is obsolete: ‘Derived cryptographic types are obsolete

The code that triggers this warning looks like this:

using System.Text;
using System.Security.Cryptography;

public static string ToSHA512(string s)
{
  SHA512Managed sha512 = new SHA512Managed();
  StringBuilder hash = new StringBuilder();
  byte[] hashArray = sha512.ComputeHash(Encoding.UTF8.GetBytes(s));
  foreach (byte b in hashArray)
  {
    hash.Append(b.ToString("x"));
  }
  return hash.ToString();
}

This warning appears because the classes SHA256Managed, SHA512Managed, SHA1Managed, and SHA384Managed have been deprecated. These are now replaced with SHA256, SHA512, SHA1, and SHA384, respectively.

To resolve the warning, you should replace the SHA512Managed class with its updated version.

using System.Text;
using System.Security.Cryptography;

public static string ToSHA512(string s)
{
  using (SHA512 sha512 = SHA512.Create())
  {
    StringBuilder hash = new StringBuilder();
    byte[] hashArray = sha512.ComputeHash(Encoding.UTF8.GetBytes(s));
    foreach (byte b in hashArray)
    {
      hash.Append(b.ToString("x"));
    }
    return hash.ToString();
  }
}

Both versions (the deprecated and the updated one) will return the same result.

// Deprecated version, do not use in .NET Core 6 and newer
private static string SHA1_Old(string s)
{
    SHA1Managed sha1 = new SHA1Managed();
    StringBuilder hash = new StringBuilder();
    byte[] hashArray = sha1.ComputeHash(Encoding.UTF8.GetBytes(s));
    foreach (byte b in hashArray)
    {
        hash.Append(b.ToString("x"));
    }
    return hash.ToString();
}

// New version for .NET Core 6 and newer
private static string SHA1_New(string s)
{
    using (SHA1 sha1 = SHA1.Create())
    {
        StringBuilder hash = new StringBuilder();
        byte[] hashArray = sha1.ComputeHash(Encoding.UTF8.GetBytes(s));
        foreach (byte b in hashArray)
        {
            hash.Append(b.ToString("x"));
        }
        return hash.ToString();
    }
}