Question

我使用以下代码加密和解密敏感数据。

这是阻止所有攻击的加密/解密的最佳方式吗？

string passwordKey = "EncryptionTestKey"
string encryptedstring = StringCipher.Encrypt("text to encrypt", passwordKey);  
string decryptedstring = StringCipher.Decrypt(encryptedstring, passwordKey);

类：

public static class StringCipher {
 // This constant is used to determine the keysize of the encryption algorithm in bits.
 // We divide this by 8 within the code below to get the equivalent number of bytes.
 private
 const int Keysize = 256;

 // This constant determines the number of iterations for the password bytes generation function.
 private
 const int DerivationIterations = 1000;

 public static string Encrypt(string plainText, string passPhrase) {
  // Salt and IV is randomly generated each time, but is preprended to encrypted cipher text
  // so that the same Salt and IV values can be used when decrypting.  
  var saltStringBytes = Generate256BitsOfRandomEntropy();
  var ivStringBytes = Generate256BitsOfRandomEntropy();
  var plainTextBytes = Encoding.UTF8.GetBytes(plainText);
  using(var password = new Rfc2898DeriveBytes(passPhrase, saltStringBytes, DerivationIterations)) {
   var keyBytes = password.GetBytes(Keysize / 8);
   using(var symmetricKey = new RijndaelManaged()) {
    symmetricKey.BlockSize = 256;
    symmetricKey.Mode = CipherMode.CBC;
    symmetricKey.Padding = PaddingMode.PKCS7;
    using(var encryptor = symmetricKey.CreateEncryptor(keyBytes, ivStringBytes)) {
     using(var memoryStream = new MemoryStream()) {
      using(var cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write)) {
       cryptoStream.Write(plainTextBytes, 0, plainTextBytes.Length);
       cryptoStream.FlushFinalBlock();
       // Create the final bytes as a concatenation of the random salt bytes, the random iv bytes and the cipher bytes.
       var cipherTextBytes = saltStringBytes;
       cipherTextBytes = cipherTextBytes.Concat(ivStringBytes).ToArray();
       cipherTextBytes = cipherTextBytes.Concat(memoryStream.ToArray()).ToArray();
       memoryStream.Close();
       cryptoStream.Close();
       return Convert.ToBase64String(cipherTextBytes);
      }
     }
    }
   }
  }
 }

 public static string Decrypt(string cipherText, string passPhrase) {
  // Get the complete stream of bytes that represent:
  // [32 bytes of Salt] + [32 bytes of IV] + [n bytes of CipherText]
  var cipherTextBytesWithSaltAndIv = Convert.FromBase64String(cipherText);
  // Get the saltbytes by extracting the first 32 bytes from the supplied cipherText bytes.
  var saltStringBytes = cipherTextBytesWithSaltAndIv.Take(Keysize / 8).ToArray();
  // Get the IV bytes by extracting the next 32 bytes from the supplied cipherText bytes.
  var ivStringBytes = cipherTextBytesWithSaltAndIv.Skip(Keysize / 8).Take(Keysize / 8).ToArray();
  // Get the actual cipher text bytes by removing the first 64 bytes from the cipherText string.
  var cipherTextBytes = cipherTextBytesWithSaltAndIv.Skip((Keysize / 8) * 2).Take(cipherTextBytesWithSaltAndIv.Length - ((Keysize / 8) * 2)).ToArray();

  using(var password = new Rfc2898DeriveBytes(passPhrase, saltStringBytes, DerivationIterations)) {
   var keyBytes = password.GetBytes(Keysize / 8);
   using(var symmetricKey = new RijndaelManaged()) {
    symmetricKey.BlockSize = 256;
    symmetricKey.Mode = CipherMode.CBC;
    symmetricKey.Padding = PaddingMode.PKCS7;
    using(var decryptor = symmetricKey.CreateDecryptor(keyBytes, ivStringBytes)) {
     using(var memoryStream = new MemoryStream(cipherTextBytes)) {
      using(var cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read)) {
       var plainTextBytes = new byte[cipherTextBytes.Length];
       var decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
       memoryStream.Close();
       cryptoStream.Close();
       return Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount);
      }
     }
    }
   }
  }
 }

 private static byte[] Generate256BitsOfRandomEntropy() {
  var randomBytes = new byte[32]; // 32 Bytes will give us 256 bits.
  using(var rngCsp = new RNGCryptoServiceProvider()) {
   // Fill the array with cryptographically secure random bytes.
   rngCsp.GetBytes(randomBytes);
  }
  return randomBytes;
 }
}

加密和解密敏感数据

0 个答案: