我生成一個隨機IV,這個IV附加(以普通字節表示)到加密味精的前面,如下所示;Java(Android)解密附帶IV的味精
public String encrypt(String plainText, byte[] encryptionKey) throws Exception {
SecretKeySpec key = new SecretKeySpec(encryptionKey, "AES");
cipher.init(Cipher.ENCRYPT_MODE, key, iV);
byte[] data = new byte[iV.getIV().length + plainText.getBytes("UTF-8").length];
// Merge together plain IV and encrypted cipher text
System.arraycopy(iV.getIV(), 0, data, 0, iV.getIV().length);
System.arraycopy(cipher.doFinal(plainText.getBytes("UTF-8")), 0, data, iV.getIV().length, plainText.getBytes("UTF-8").length);
return Base64.encodeToString(data, Base64.DEFAULT);
}
該消息在使用WiFi Direct的設備之間發送。這在我的MainActivity中處理;
case MESSAGE_READ:
byte[] readBuf = (byte[]) msg.obj;
crypto.iV = new IvParameterSpec(Arrays.copyOf(readBuf, 16));
// Construct a string from the valid bytes in the buffer
String readMessage = new String(readBuf, 0, msg.arg1);
Log.d(TAG, readMessage);
try {
String decryptMsg = crypto.decrypt(readMessage, SECRET_KEY);
// Present the message
(chatFragment).pushMessage("Buddy (decrypt): " + decryptMsg);
Log.d(TAG, decryptMsg);
} catch (Exception e) {
e.printStackTrace();
}
// Present the message (comment out after testing!)
//(chatFragment).pushMessage("Buddy (encrypt): " + readMessage);
break;
在解密期間,它會失敗並顯示警告;
04-04 14:55:05.770:W/System.err的(9847):javax.crypto.IllegalBlockSizeException:最後的塊在解密不全
04-04 14:55:05.789:W/System.err(9847):at com.android.org.bouncycastle.jcajce.provider.symmetric.util.BaseBlockCipher.engineDoFinal(BaseBlockCipher.java:850)
04-04 14:55:05.790:W/System .err(9847):at javax.crypto.Cipher.doFinal(Cipher.java:1340)
04-04 14:55:05.790:W/System.err(9847):at com.example.cryptochat。 Crypto.decrypt(Crypto.jav一:52)
04-04 14:55:05.790:W/System.err的(9847):在com.example.cryptochat.MainActivity.handleMessage(MainActivity.java:463)
的問題在於解密方法,但我不確定我做錯了什麼。該方法在下面;
public String decrypt(String cipherText, byte[] encryptionKey) throws Exception {
SecretKeySpec key = new SecretKeySpec(encryptionKey, "AES");
cipher.init(Cipher.DECRYPT_MODE, key, iV);
String decrypt = new String(cipher.doFinal(Base64.decode(cipherText, Base64.DEFAULT)));
decrypt = new String(Arrays.copyOfRange(decrypt.getBytes(), 16, decrypt.getBytes().length));
return decrypt;
}
感謝您的幫助robert!我可以用附加的IV解密文本,但它在解密「cipherTextWithoutIv」時不起作用。解密後應該怎樣刪除Iv? – Danran 2015-04-04 14:37:01
不要對base64編碼的字符串進行字符串操作。解碼並執行操作。 – Robert 2015-04-04 15:03:51
我仍然無法從解密的消息中成功刪除IV。 CopyOfRange()似乎不工作,對我應該做什麼的任何建議? (*更新代碼) – Danran 2015-04-04 20:10:10