将文件转换为加密文件并在服务器上解密（使用公钥加密）

Question

我试图使用RSA加密/解密文件。但我看不到文件中的数据。

这里是代码：

 // To encrypt a file 

    private static void encrypt(InputStream input, OutputStream output, PublicKey key) 
     throws IOException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException  { 
    final Cipher encrypt = Cipher.getInstance(ALGORITHM); 
    // encrypt the plain text using the public key 
     encrypt.init(Cipher.ENCRYPT_MODE, key); 
     // encrypt.doFinal(); 
    output = new CipherOutputStream(output,encrypt); 
    writeBytes(input, output, encrypt); 
      output.close(); 
} 


    // To decrypt the file 

private static void decrypt(InputStream input, OutputStream output, PrivateKey key) 
     throws IOException,NoSuchAlgorithmException,InvalidKeyException,NoSuchPaddingException,BadPaddingException,IllegalBlockSizeException { 
     final Cipher decrypt = Cipher.getInstance(ALGORITHM); 

    // decrypt the text using the private key 
    decrypt.init(Cipher.DECRYPT_MODE, key); 
    input = new CipherInputStream(input, decrypt); 
    writeBytes(input, output, decrypt); 
      input.close(); 
} 

// To write on the file from the inputstream 

private static void writeBytes(InputStream input, OutputStream output, Cipher cipher) 
     throws IOException, IllegalBlockSizeException,BadPaddingException { 
    byte[] writeBuffer = new byte[512]; 
    int readBytes = 0; 

    while ((readBytes = input.read(writeBuffer)) >= 0) { 
       System.out.println(readBytes); 




       // String text = input.read(writeBuffer); 
       // cipher.doFinal(); 
       try{ 
        System.out.println("Here"); 
     output.write(writeBuffer, 0, readBytes); 
       } 
       catch(Exception e){ 
       e.printStackTrace(); 
       } 
    } 

    output.close(); 
    input.close(); 
} 

主要功能：

// Check if the pair of keys are present else generate those. 
    if (!areKeysPresent()) { 
    // Method generates a pair of keys using the RSA algorithm and stores it 
    // in their respective files 
    generateKey(); 
    } 

    final String originalText = "Text to be encrypted "; 
    ObjectInputStream inputStream = null; 

    String clearFile = "/UploadFile/Log.txt";  
    String encryptedFile = "/UploadFile/LogE.txt";  
    String decryptedFile = "/UploadFile/LogD.txt"; 

    // Encrypt the string using the public key 
    inputStream = new ObjectInputStream(new FileInputStream(PUBLIC_KEY_FILE)); 
    final PublicKey publicKey = (PublicKey) inputStream.readObject(); 
// final byte[] cipherText = encrypt(originalText, publicKey); 

    encrypt(new FileInputStream(clearFile), new FileOutputStream(encryptedFile), publicKey); 
    System.out.println("Successfully Encrypted"); 

    } 
    // Decrypt the cipher text using the private key. 
    inputStream = new ObjectInputStream(new FileInputStream(PRIVATE_KEY_FILE)); 
    final PrivateKey privateKey = (PrivateKey) inputStream.readObject(); 
// final String plainText = decrypt(cipherText, privateKey); 

    decrypt(new FileInputStream(encryptedFile), new FileOutputStream(decryptedFile), privateKey); 
    System.out.println("Successfully Decrypted"); 


GenerateKey Function : 

public static void generateKey() { 
try { 
    final KeyPairGenerator keyGen = KeyPairGenerator.getInstance(ALGORITHM); 
    keyGen.initialize(1024); 
    final KeyPair key = keyGen.generateKeyPair(); 

    File privateKeyFile = new File(PRIVATE_KEY_FILE); 
    File publicKeyFile = new File(PUBLIC_KEY_FILE); 

    // Create files to store public and private key 
    if (privateKeyFile.getParentFile() != null) { 
    privateKeyFile.getParentFile().mkdirs(); 
    } 
    privateKeyFile.createNewFile(); 

    if (publicKeyFile.getParentFile() != null) { 
    publicKeyFile.getParentFile().mkdirs(); 
    } 
    publicKeyFile.createNewFile(); 

    // Saving the Public key in a file 
    ObjectOutputStream publicKeyOS = new ObjectOutputStream(
     new FileOutputStream(publicKeyFile)); 
    publicKeyOS.writeObject(key.getPublic()); 
    publicKeyOS.close(); 

    // Saving the Private key in a file 
    ObjectOutputStream privateKeyOS = new ObjectOutputStream(
     new FileOutputStream(privateKeyFile)); 
    privateKeyOS.writeObject(key.getPrivate()); 
    privateKeyOS.close(); 
} catch (Exception e) { 
    e.printStackTrace(); 
} 

    } 

我没有收到在加密和解密的文件中的任何数据。

clearFile是原始数据文件，encryptedFile是加密数据，decryptedFile是解密数据。

请帮助，我在这里失踪。

Answer 1

您不使用RSA进行数据加密。您使用它来加密对称密钥，并使用对称密钥来加密数据。公钥算法用于密钥传输或密钥协议，而不是数据。

您应该为您的应用程序使用CMS（S/MIME）或PGP库。

Answer 2

我不知道您尝试加密的文件的大小是多少，但在RSA中，您无法加密过多的数据。它是N参数中的一部分，因此确保您的数据应该短于密钥。也许这是问题所在。

通常，您使用公钥加密来加密对称密钥（例如AES），然后使用加密的对称密钥有效地加密数据。这称为混合加密。

我建议您先尝试使用AES进行加密，然后尝试仅加密AES密钥。