Ridavei.FileCrypto 1.0.0

Ridavei.FileCrypto

What is FileCrypto?

Ridavei.FileCrypto is a cross-platform .NET library that orchestrates file encryption/decryption by selecting a user-provided ICrypto implementation based on ContentType.

This package does not implement cryptography algorithms.
You provide your own ICrypto implementations (AES, custom, etc.). FileCrypto only loads the input and routes it to the right implementation.

Installation

dotnet add package Ridavei.FileCrypto

How it works

1. You implement ICrypto for a given MIME media type (ContentType).
2. You register it in FileCryptoBuilder (SetCryptoMethod).
3. You create a crypto runner for:
   • file paths (CreateFilePathCrypto()), or
   • streams (CreateStreamCrypto()), or
   • custom loaders (CreateGenericCrypto(...)).
4. You call Encrypt(...) / Decrypt(...).

Important behavior

• Crypto methods are stored by normalized media type (e.g. "text/plain"), case-insensitive.
• Registering a method for an already-registered media type overwrites the previous one.

API contract (important)

Who owns streams?

• The stream returned by ICrypto.Encrypt(...) / ICrypto.Decrypt(...) is owned by the caller (you) and should be disposed by the caller.
• Your ICrypto implementation must return a new, independent Stream instance (it must not return the same stream instance it received).
• Your ICrypto implementation should not dispose the input stream.

Input stream lifetime (important)

• When using CreateFilePathCrypto() (file path input), the library opens the file stream internally and may dispose it after the crypto operation finishes.
• When using CreateStreamCrypto() (stream input), the input stream is owned by the caller and should be disposed by the caller.

Stream position / seeking

• ICrypto receives the input stream exactly as provided by the loader (including its current Position).
• If your algorithm requires reading from the beginning, ensure the stream is seekable and set Position = 0 in your ICrypto implementation.

Wrong password / validation

Handling a wrong password (exceptions, validation, authentication tags, etc.) is entirely the responsibility of the user-provided ICrypto implementation.

Examples

Creating a class to decrypt/encrypt files for a specific ContentType.

using System.IO;
using System.Net.Mime;

using Ridavei.FileCrypto.Interfaces;

namespace TestProgram
{
    internal sealed class TextPlainCrypto : ICrypto
    {
        public static readonly ICrypto Instance = new TextPlainCrypto();
        public static readonly ContentType TxtContentType = new (MediaTypeNames.Text.Plain);
        
        public Stream Encrypt(Stream inputData, string password)
        {
            // Implement your encryption here.
            // Must return a NEW Stream instance (independent from inputData).
            throw new NotImplementedException();
        }

        public Stream Decrypt(Stream inputData, string password)
        {
            // Implement your decryption here.
            // Must return a NEW Stream instance (independent from inputData).
            throw new NotImplementedException();
        }
    }
}

File decryption/encryption using the class created above

using System.IO;
using System.Net.Mime;

using Ridavei.FileCrypto;

namespace TestProgram
{
    class Program
    {
        private static readonly FileCryptoBuilder _builder = FileCryptoBuilder
            .CreateBuilder()
            .SetCryptoMethod(TextPlainCrypto.TxtContentType, TextPlainCrypto.Instance);
        
        public static void Main (string[] args)
        {
            ContentType contentType = TextPlainCrypto.TxtContentType;
            string filePath = "example.txt";
            string password = "<PASSWORD>";
            
            var crypto = _builder.CreateFilePathCrypto();
            using (Stream decryptedFile = crypto.Decrypt(filePath, contentType, password))
            {
                //Save/use decryptedFile.
            }
            // Similarly:
            // using (var encryptedFile = crypto.Encrypt(filePath, contentType, password)) { }
        }
    }
}

Creating extensions

using Ridavei.FileCrypto;

namespace TestProgram
{
    public static class EncryptExt
    {
        public static FileCryptoBuilder UseTextPlainCrypto(this FileCryptoBuilder builder)
        {
            return builder.SetCryptoMethod(TextPlainCrypto.TxtContentType, TextPlainCrypto.Instance);
        }
    }
}