60 lines
2.2 KiB
C#
60 lines
2.2 KiB
C#
using System.Security.Cryptography;
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namespace DysonNetwork.Drive.Storage;
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public static class FileEncryptor
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{
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public static void EncryptFile(string inputPath, string outputPath, string password)
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{
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var salt = RandomNumberGenerator.GetBytes(16);
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var key = DeriveKey(password, salt, 32);
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var nonce = RandomNumberGenerator.GetBytes(12); // For AES-GCM
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using var aes = new AesGcm(key, 16); // Specify 16-byte tag size explicitly
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var plaintext = File.ReadAllBytes(inputPath);
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var magic = "DYSON1"u8.ToArray();
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var contentWithMagic = new byte[magic.Length + plaintext.Length];
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Buffer.BlockCopy(magic, 0, contentWithMagic, 0, magic.Length);
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Buffer.BlockCopy(plaintext, 0, contentWithMagic, magic.Length, plaintext.Length);
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var ciphertext = new byte[contentWithMagic.Length];
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var tag = new byte[16];
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aes.Encrypt(nonce, contentWithMagic, ciphertext, tag);
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// Save as: [salt (16)][nonce (12)][tag (16)][ciphertext]
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using var fs = new FileStream(outputPath, FileMode.Create, FileAccess.Write);
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fs.Write(salt);
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fs.Write(nonce);
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fs.Write(tag);
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fs.Write(ciphertext);
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}
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public static void DecryptFile(string inputPath, string outputPath, string password)
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{
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var input = File.ReadAllBytes(inputPath);
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var salt = input[..16];
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var nonce = input[16..28];
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var tag = input[28..44];
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var ciphertext = input[44..];
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var key = DeriveKey(password, salt, 32);
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var decrypted = new byte[ciphertext.Length];
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using var aes = new AesGcm(key, 16); // Specify 16-byte tag size explicitly
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aes.Decrypt(nonce, ciphertext, tag, decrypted);
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var magic = "DYSON1"u8.ToArray();
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if (magic.Where((t, i) => decrypted[i] != t).Any())
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throw new CryptographicException("Incorrect password or corrupted file.");
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var plaintext = decrypted[magic.Length..];
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File.WriteAllBytes(outputPath, plaintext);
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}
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private static byte[] DeriveKey(string password, byte[] salt, int keyBytes)
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{
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using var pbkdf2 = new Rfc2898DeriveBytes(password, salt, 100_000, HashAlgorithmName.SHA256);
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return pbkdf2.GetBytes(keyBytes);
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}
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} |