SecureStringHash

Hash any SecureString securely with any HashAlgorithm and any Encoding.

Prevents copies of the string from remaining in memory (unlike when converting to a managed string) and zeros out all memory used to store intermediate values.

Usage

Use the extension method...

// Use any HashAlgorithm
using (HashAlgorithm hashAlgorithm = new SHA256CryptoServiceProvider())
{
    // Uses UTF-8 encoding by default
    byte[] hash = secureString.Hash(hashAlgorithm); // <-- The extension method being used
    
    // Alternatively you can specify the encoding
    byte[] hashUtf16 = secureString.Hash(hashAlgorithm, Encoding.Unicode);
}

The SecureString encoding is first converted from UTF-16 (the encoding .NET uses for all characters) to the encoding specified, or UTF-8 if no encoding is chosen, before being hashed.

... or just copy the short code

It's all in SecureStringHashExtensions.cs. Use it how you wish.