Obtain SHA-256 string of a string

Question

I have some string and I want to hash it with the SHA-256 hash function using C#. I want something like this:

 string hashString = sha256_hash("samplestring");

Is there something built into the framework to do this?

Answer 1

The implementation could be like that

public static String sha256_hash(String value) {
  StringBuilder Sb = new StringBuilder();

  using (SHA256 hash = SHA256Managed.Create()) {
    Encoding enc = Encoding.UTF8;
    Byte[] result = hash.ComputeHash(enc.GetBytes(value));

    foreach (Byte b in result)
      Sb.Append(b.ToString("x2"));
  }

  return Sb.ToString();
}

Edit: Linq implementation is more concise, but, probably, less readable:

public static String sha256_hash(String value) {
  using (SHA256 hash = SHA256Managed.Create()) {
    return String.Concat(hash
      .ComputeHash(Encoding.UTF8.GetBytes(value))
      .Select(item => item.ToString("x2")));
  }
} 

Edit 2: .NET Core , .NET5, .NET6 ...

public static String sha256_hash(string value)
{
    StringBuilder Sb = new StringBuilder();

    using (var hash = SHA256.Create())            
    {
        Encoding enc = Encoding.UTF8;
        byte[] result = hash.ComputeHash(enc.GetBytes(value));

        foreach (byte b in result)
            Sb.Append(b.ToString("x2"));
    }

    return Sb.ToString();
}

Answer 2

From .NET 5 onwards, you can use the new Convert.ToHexString method to convert the hash byte array into a (hex) string without having to use a StringBuilder or .ToString("X0"), etc.:

public static string HashWithSHA256(string value)
{
  using var hash = SHA256.Create();
  var byteArray = hash.ComputeHash(Encoding.UTF8.GetBytes(value));
  return Convert.ToHexString(byteArray);
}

Answer 3

I was looking for an in-line solution, and was able to compile the below from Dmitry's answer:

public static String sha256_hash(string value)
{
    return (System.Security.Cryptography.SHA256.Create()
            .ComputeHash(Encoding.UTF8.GetBytes(value))
            .Select(item => item.ToString("x2")));
}

Answer 4

Simply:

string sha256(string s) => Convert.ToHexString(SHA256.HashData(Encoding.UTF8.GetBytes(s)));

Answer 5

I tried all of the above methods and none worked for me. This one is one I made that works flawlessly:

public static string Encrypt(string input)
{
    using (SHA256 sha256 = SHA256.Create())
    {
        // Convert the input string to a byte array
        byte[] inputBytes = Encoding.UTF8.GetBytes(input);

        // Compute the hash value of the input bytes
        byte[] hashBytes = sha256.ComputeHash(inputBytes);

        // Convert the hash bytes to a hexadecimal string
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < hashBytes.Length; i++)
        {
            sb.Append(hashBytes[i].ToString("x2"));
        }

        return sb.ToString();
    }
}

Make sure to be using System.Security.Cryptography at the beginning of your code

using System.Security.Cryptography