Java AES和使用我自己的密鑰

Question

我想用我自己的密鑰使用AES加密字符串。但是我在密鑰的位長上遇到了問題。你可以檢查我的代碼，看看我需要修復/更改。

public static void main(String[] args) throws Exception { 
    String username = "bob@google.org"; 
    String password = "Password1"; 
    String secretID = "BlahBlahBlah"; 
    String SALT2 = "deliciously salty"; 

    // Get the Key 
    byte[] key = (SALT2 + username + password).getBytes(); 
    System.out.println((SALT2 + username + password).getBytes().length); 

    // Need to pad key for AES 
    // TODO: Best way? 

    // Generate the secret key specs. 
    SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES"); 

    // Instantiate the cipher 
    Cipher cipher = Cipher.getInstance("AES"); 
    cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec); 

    byte[] encrypted = cipher.doFinal((secrectID).getBytes()); 
    System.out.println("encrypted string: " + asHex(encrypted)); 

    cipher.init(Cipher.DECRYPT_MODE, secretKeySpec); 
    byte[] original = cipher.doFinal(encrypted); 
    String originalString = new String(original); 
    System.out.println("Original string: " + originalString + "\nOriginal string (Hex): " + asHex(original)); 
} 

現在我得到一個異常 「無效的AES密鑰長度：86個字節」。我需要填寫我的鑰匙嗎？我應該怎麼做？

我還需要爲ECB或CBC設置任何東西嗎？

感謝

Answer 1

您應該使用SHA-1從您的密鑰生成散列並將結果修剪爲128位（16字節）。

另外不要從字符串生成字節數組通過getBytes（）它使用平臺默認的字符集。所以密碼「blaöä」在不同的平臺上產生不同的字節數組。

byte[] key = (SALT2 + username + password).getBytes("UTF-8"); 
MessageDigest sha = MessageDigest.getInstance("SHA-1"); 
key = sha.digest(key); 
key = Arrays.copyOf(key, 16); // use only first 128 bit 

SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES"); 

編輯： 如果需要256位，因爲你需要下載「Java加密擴展（JCE）無限強度權限策略文件」 Oracle download link密鑰大小，使用SHA-256散列和刪除陣列。 copyOf一行。 「ECB」是默認的密碼模式，「PKCS5Padding」是默認的填充。 你可以使用以下格式通過Cipher.getInstance字符串中使用不同的密碼模式和填充模式：「密碼/模式/填充」

對於使用CTS AES和PKCS5Padding的字符串：「AES/CTS/PKCS5Padding」

Answer 2

您應該使用的KeyGenerator生成密鑰，

AES密鑰長度爲128，192和256位，具體取決於您要使用的密碼。

在本教程here

下面一起來看看是基於密碼的加密代碼，這必須通過System.in正在進入你可以改變，如果你想，要使用存儲的密碼。

 PBEKeySpec pbeKeySpec; 
     PBEParameterSpec pbeParamSpec; 
     SecretKeyFactory keyFac; 

     // Salt 
     byte[] salt = { 
      (byte)0xc7, (byte)0x73, (byte)0x21, (byte)0x8c, 
      (byte)0x7e, (byte)0xc8, (byte)0xee, (byte)0x99 
     }; 

     // Iteration count 
     int count = 20; 

     // Create PBE parameter set 
     pbeParamSpec = new PBEParameterSpec(salt, count); 

     // Prompt user for encryption password. 
     // Collect user password as char array (using the 
     // "readPassword" method from above), and convert 
     // it into a SecretKey object, using a PBE key 
     // factory. 
     System.out.print("Enter encryption password: "); 
     System.out.flush(); 
     pbeKeySpec = new PBEKeySpec(readPassword(System.in)); 
     keyFac = SecretKeyFactory.getInstance("PBEWithMD5AndDES"); 
     SecretKey pbeKey = keyFac.generateSecret(pbeKeySpec); 

     // Create PBE Cipher 
     Cipher pbeCipher = Cipher.getInstance("PBEWithMD5AndDES"); 

     // Initialize PBE Cipher with key and parameters 
     pbeCipher.init(Cipher.ENCRYPT_MODE, pbeKey, pbeParamSpec); 

     // Our cleartext 
     byte[] cleartext = "This is another example".getBytes(); 

     // Encrypt the cleartext 
     byte[] ciphertext = pbeCipher.doFinal(cleartext); 

Answer 3

import java.security.Key; 
import javax.crypto.Cipher; 
import javax.crypto.spec.SecretKeySpec; 
import sun.misc.*; 
import java.io.BufferedReader; 
import java.io.FileReader; 

public class AESFile 
{ 
private static String algorithm = "AES"; 
private static byte[] keyValue=new byte[] {'0','2','3','4','5','6','7','8','9','1','2','3','4','5','6','7'};// your key 

    // Performs Encryption 
    public static String encrypt(String plainText) throws Exception 
    { 
      Key key = generateKey(); 
      Cipher chiper = Cipher.getInstance(algorithm); 
      chiper.init(Cipher.ENCRYPT_MODE, key); 
      byte[] encVal = chiper.doFinal(plainText.getBytes()); 
      String encryptedValue = new BASE64Encoder().encode(encVal); 
      return encryptedValue; 
    } 

    // Performs decryption 
    public static String decrypt(String encryptedText) throws Exception 
    { 
      // generate key 
      Key key = generateKey(); 
      Cipher chiper = Cipher.getInstance(algorithm); 
      chiper.init(Cipher.DECRYPT_MODE, key); 
      byte[] decordedValue = new BASE64Decoder().decodeBuffer(encryptedText); 
      byte[] decValue = chiper.doFinal(decordedValue); 
      String decryptedValue = new String(decValue); 
      return decryptedValue; 
    } 

//generateKey() is used to generate a secret key for AES algorithm 
    private static Key generateKey() throws Exception 
    { 
      Key key = new SecretKeySpec(keyValue, algorithm); 
      return key; 
    } 

    // performs encryption & decryption 
    public static void main(String[] args) throws Exception 
    { 
     FileReader file = new FileReader("C://myprograms//plaintext.txt"); 
     BufferedReader reader = new BufferedReader(file); 
     String text = ""; 
     String line = reader.readLine(); 
    while(line!= null) 
     { 
      text += line; 
    line = reader.readLine(); 
     } 
     reader.close(); 
    System.out.println(text); 

      String plainText = text; 
      String encryptedText = AESFile.encrypt(plainText); 
      String decryptedText = AESFile.decrypt(encryptedText); 

      System.out.println("Plain Text : " + plainText); 
      System.out.println("Encrypted Text : " + encryptedText); 
      System.out.println("Decrypted Text : " + decryptedText); 
    } 
} 

Answer 4

這將工作。

public class CryptoUtils { 

    private final String TRANSFORMATION = "AES"; 
    private final String encodekey = "1234543444555666"; 
    public String encrypt(String inputFile) 
      throws CryptoException { 
     return doEncrypt(encodekey, inputFile); 
    } 


    public String decrypt(String input) 
      throws CryptoException { 
    // return doCrypto(Cipher.DECRYPT_MODE, key, inputFile); 
    return doDecrypt(encodekey,input); 
    } 

    private String doEncrypt(String encodekey, String inputStr) throws CryptoException { 
     try { 

      Cipher cipher = Cipher.getInstance(TRANSFORMATION); 

      byte[] key = encodekey.getBytes("UTF-8"); 
      MessageDigest sha = MessageDigest.getInstance("SHA-1"); 
      key = sha.digest(key); 
      key = Arrays.copyOf(key, 16); // use only first 128 bit 

      SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES"); 

      cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec); 

      byte[] inputBytes = inputStr.getBytes();  
      byte[] outputBytes = cipher.doFinal(inputBytes); 

      return Base64Utils.encodeToString(outputBytes); 

     } catch (NoSuchPaddingException | NoSuchAlgorithmException 
       | InvalidKeyException | BadPaddingException 
       | IllegalBlockSizeException | IOException ex) { 
      throw new CryptoException("Error encrypting/decrypting file", ex); 
     } 
    } 


    public String doDecrypt(String encodekey,String encrptedStr) { 
      try {  

       Cipher dcipher = Cipher.getInstance(TRANSFORMATION); 
       dcipher = Cipher.getInstance("AES"); 
       byte[] key = encodekey.getBytes("UTF-8"); 
       MessageDigest sha = MessageDigest.getInstance("SHA-1"); 
       key = sha.digest(key); 
       key = Arrays.copyOf(key, 16); // use only first 128 bit 

       SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES"); 

       dcipher.init(Cipher.DECRYPT_MODE, secretKeySpec); 
      // decode with base64 to get bytes 

       byte[] dec = Base64Utils.decode(encrptedStr.getBytes()); 
       byte[] utf8 = dcipher.doFinal(dec); 

       // create new string based on the specified charset 
       return new String(utf8, "UTF8"); 

      } catch (Exception e) { 

      e.printStackTrace(); 

      } 
     return null; 
     } 
} 

Answer 5

byte[] seed = (SALT2 + username + password).getBytes(); 
    SecureRandom random = new SecureRandom(seed); 
    KeyGenerator generator; 
    generator = KeyGenerator.getInstance("AES"); 
    generator.init(random); 
    generator.init(256); 
    Key keyObj = generator.generateKey();