GzipCompression.cs

using System.IO.Compression;
using System.Security.Cryptography;
using System.Text;

namespace Intersect.Compression;

/// <summary>
/// Contains several wrapper methods used to generalize code in areas of the engine related to compressing and decompressing files and data.
/// </summary>
public static partial class GzipCompression
{

    // Our cryptographic provider, and the key to be used to encrypt. Note, it NEEDS to be 16 characters or more!
    private static AesCryptoServiceProvider cryptoProvider;
    private static string cryptoKey = "T3ZncHUsIGdueHIgdmcgYmUgeXJuaXIgdmcu";

    /// <summary>
    /// Initialize our Cryptographic Provider and make it usable.
    /// </summary>
    private static void CreateProvider()
    {
        cryptoProvider = new AesCryptoServiceProvider();

        // Take a few bytes out of this delicious morsel and grow stronk.
        var keyBytes = ASCIIEncoding.ASCII.GetBytes(cryptoKey);
        cryptoProvider.Key = [.. keyBytes.Take(16)];
        cryptoProvider.IV = [.. ((IEnumerable<byte>)keyBytes).Reverse().Take(16)];
    }

    /// <summary>
    /// Read a decompressed unencrypted string from a specified file.
    /// </summary>
    /// <param name="fileName">The file to decompress.</param>
    /// <returns>Returns the decompressed file's content as a string.</returns>
    public static string ReadDecompressedString(string fileName)
    {
        using (var reader = new StreamReader(CreateDecompressedFileStream(fileName)))
        {
            return reader.ReadToEnd();
        }
    }

    /// <summary>
    /// Read a decompressed unencrypted stream from a specified file.
    /// </summary>
    /// <param name="fileName">The file to decompress.</param>
    /// <returns>Returns a decompressed <see cref="CryptoStream"/> of the file's content.</returns>
    public static CryptoStream CreateDecompressedFileStream(string fileName)
    {
        if (cryptoProvider == null)
        {
            CreateProvider();
        }

        return new CryptoStream(new GZipStream(File.OpenRead(fileName), CompressionMode.Decompress, false), cryptoProvider.CreateDecryptor(), CryptoStreamMode.Read);
    }

    /// <summary>
    /// Read decompressed unencrypted data from an existing <see cref="Stream"/>.
    /// </summary>
    /// <param name="stream">The <see cref="Stream"/> to write data from.</param>
    /// <returns>Returns a decompressed <see cref="CryptoStream"/> of the stream's content.</returns>
    public static CryptoStream CreateDecompressedFileStream(Stream stream)
    {
        if (cryptoProvider == null)
        {
            CreateProvider();
        }

        return new CryptoStream(new GZipStream(stream, CompressionMode.Decompress, false), cryptoProvider.CreateDecryptor(), CryptoStreamMode.Read);
    }

    /// <summary>
    /// Writes the given string to a compressed encrypted file.
    /// </summary>
    /// <param name="fileName">The file to write the string to.</param>
    /// <param name="data">The string to compress and write to the file.</param>
    public static void WriteCompressedString(string fileName, string data)
    {
        using (var stream = CreateCompressedFileStream(fileName))
        {
            var bytes = Encoding.UTF8.GetBytes(data);
            stream.Write(bytes, 0, bytes.Length);
        }
    }

    /// <summary>
    /// Creates a compressed encrypted FileStream to write data to.
    /// </summary>
    /// <param name="fileName">The file to write the data to.</param>
    /// <returns>Returns a <see cref="CryptoStream"/> to write data to, saving compressed data to a file.</returns>
    public static CryptoStream CreateCompressedFileStream(string fileName)
    {
        if (cryptoProvider == null)
        {
            CreateProvider();
        }

        return new CryptoStream(new GZipStream(new FileStream(fileName, FileMode.Create), CompressionMode.Compress, false), cryptoProvider.CreateEncryptor(), CryptoStreamMode.Write);
    }

}