QuizSystem/Quizzer-8/Quizzer/Extensions/Extensions.cs

using Newtonsoft.Json.Linq;
using System.IO.Compression;
using System.Security.Cryptography;
using System.Text;

namespace Quizzer.Extensions
{
    public static class Extensions
    {
        /// <summary>
        /// Compresses a string and returns a deflate compressed, Base64 encoded string.
        /// </summary>
        /// <param name="uncompressedString">String to compress</param>
        public static string Compress(this string uncompressedString)
        {
            byte[] compressedBytes;

            using (var uncompressedStream = new MemoryStream(Encoding.UTF8.GetBytes(uncompressedString)))
            {
                using (var compressedStream = new MemoryStream())
                {
                    // setting the leaveOpen parameter to true to ensure that compressedStream will not be closed when compressorStream is disposed
                    // this allows compressorStream to close and flush its buffers to compressedStream and guarantees that compressedStream.ToArray() can be called afterward
                    // although MSDN documentation states that ToArray() can be called on a closed MemoryStream, I don't want to rely on that very odd behavior should it ever change
                    using (var compressorStream = new DeflateStream(compressedStream, CompressionLevel.Fastest, true))
                    {
                        uncompressedStream.CopyTo(compressorStream);
                    }

                    // call compressedStream.ToArray() after the enclosing DeflateStream has closed and flushed its buffer to compressedStream
                    compressedBytes = compressedStream.ToArray();
                }
            }

            return Convert.ToBase64String(compressedBytes);
        }

        /// <summary>
        /// Decompresses a deflate compressed, Base64 encoded string and returns an uncompressed string.
        /// </summary>
        /// <param name="compressedString">String to decompress.</param>
        public static string Decompress(this string compressedString)
        {
            byte[] decompressedBytes;

            var compressedStream = new MemoryStream(Convert.FromBase64String(compressedString));

            using (var decompressorStream = new DeflateStream(compressedStream, CompressionMode.Decompress))
            {
                using (var decompressedStream = new MemoryStream())
                {
                    decompressorStream.CopyTo(decompressedStream);

                    decompressedBytes = decompressedStream.ToArray();
                }
            }

            return Encoding.UTF8.GetString(decompressedBytes);
        }
        /// <summary>
        /// Hashes the string using SHA256
        /// </summary>
        /// <param name="plaintext">
        /// What needs to be hashed
        /// </param>
        /// <returns>
        /// The hash
        /// </returns>
        public static string HashSHA256(this string plaintext)
        {
            StringBuilder Sb = new StringBuilder();

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

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

            return Sb.ToString();
        }
        /// <summary>
        /// Hashes the string using MD5
        /// </summary>
        /// <param name="plaintext">
        /// What needs to be hashed
        /// </param>
        /// <returns>
        /// The hash
        /// </returns>
        public static string HashMD5(this string plaintext)
        {
            StringBuilder Sb = new StringBuilder();

            using (var hash = MD5.Create())
            {
                Encoding enc = Encoding.UTF8;
                byte[] result = hash.ComputeHash(enc.GetBytes(plaintext));

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

            return Sb.ToString();
        }
    }
}