using System;

using System.Security.Cryptography;

using System.Text;

using System.Linq;

​

public static class Program

{

    public static void Main()

    {

        string r = "d1a007ea97ee1fe227e4a40b088807115a3ac6012f929f1d85211c8d5ce474896e62ac6cdb04f2db17aa13d63dda65da0955703eb4f778241b782dc821ad6a66eae0e6ae737e0a789b88e87e578fc749af0aee3732e808812fe8b4c86243d21855a3680807ce029fe0438ff3cc38df378b46beaa21246eadd7f6ee6c0eb8d54e";

        string dec = Decrypt(r);

        Console.WriteLine($"Decrypted: \"{dec}\"");

    }

​

    public static byte[] HexStringToByteArray(string s)

    {

        byte[] buffer = new byte[s.Length / 2];

        for (int i = 0; i < s.Length; i += 2)

        {

            buffer[i / 2] = (byte)Convert.ToByte(s.Substring(i, 2), 16);

        }

​

        return buffer;

    }

​

    public static string ByteArrayToHexString(byte[] data)

    {

        StringBuilder sb = new StringBuilder(data.Length * 3);

        foreach (byte b in data)

        {

            sb.Append(Convert.ToString(b, 16).PadLeft(2, '0'));

        }

​

        return sb.ToString();

    }

​

    public static string Decrypt(string cipher)

    {

        string password = "a1503725ba805cc3ff6aa340923ad971cf17e33ef65753332ac8ae0e96a26e21";

        byte[] key = HexStringToByteArray(password);

        // Initialize AES implementation

        var aesObj = new AesGcm(key);

        // Decode

        byte[] encryptedData = HexStringToByteArray(cipher);

        // Extract parameter sizes

        int nonceSize = 12;

        int tagSize = 16;

        int cipherSize = encryptedData.Length - nonceSize - tagSize;

        // Extract parameters

        var nonce = encryptedData.Take(nonceSize).ToArray();

        var cipherBytes = encryptedData.Skip(nonceSize).Take(cipherSize).ToArray();

        var tag = encryptedData.Skip(nonceSize+cipherSize).Take(tagSize).ToArray();

        // Decrypt

        byte[] plainBytes = new byte[cipherSize];

        Console.WriteLine(ByteArrayToHexString(nonce));

        Console.WriteLine(ByteArrayToHexString(cipherBytes));

        Console.WriteLine(ByteArrayToHexString(tag));

        aesObj.Decrypt(nonce, cipherBytes, tag, plainBytes);

        // Convert plain bytes back into string

        return Encoding.UTF8.GetString(plainBytes);

    }

}