[英]How to decrypt encrypted string using AES Algorithm in Java?
我无法用Java解密AES加密的文本。 这是我的代码:
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.xml.bind.DatatypeConverter;
public class aesencrypt {
public static void main(String[] args) throws Exception {
String plainText = "Hello World";
System.out.println("Original Text:" + plainText);
SecretKey secKey = getSecretEncryptionKey();
System.out.println("AES Key (Hex Form):"+bytesToHex(secKey.getEncoded()));
String encryptedText = bytesToHex(encryptText(plainText, secKey));
System.out.println("Encrypted Text (Hex Form):"+encryptedText);
String decryptedText = decryptText(encryptedText, secKey);
System.out.println("Descrypted Text:"+decryptedText);
}
public static SecretKey getSecretEncryptionKey() throws Exception{
KeyGenerator generator = KeyGenerator.getInstance("AES");
generator.init(128); // The AES key size in number of bits
SecretKey secKey = generator.generateKey();
return secKey;
}
public static byte[] encryptText(String plainText,SecretKey secKey) throws Exception{
// AES defaults to AES/ECB/PKCS5Padding in Java 7
Cipher aesCipher = Cipher.getInstance("AES");
aesCipher.init(Cipher.ENCRYPT_MODE, secKey);
byte[] byteCipherText = aesCipher.doFinal(plainText.getBytes());
return byteCipherText;
}
public static String decryptText(String encrypted, SecretKey secKey) throws Exception {
// AES defaults to AES/ECB/PKCS5Padding in Java 7
Cipher aesCipher = Cipher.getInstance("AES");
aesCipher.init(Cipher.DECRYPT_MODE, secKey);
byte[] bytePlainText = aesCipher.doFinal(encrypted.getBytes());
return new String(bytePlainText);
}
private static String bytesToHex(byte[] hash) {
return DatatypeConverter.printHexBinary(hash);
}
}
运行此命令时,在以下输出中出现错误:
Original Text:Hello World
AES Key (Hex Form):4690FFCDC7B5E8B128F5BF45F0920527
Encrypted Text (Hex Form):7C092F40D592F9DF83F3D4E976612928
Exception in thread "main" javax.crypto.BadPaddingException: Given final block not properly padded
at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:989)
at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:845)
at com.sun.crypto.provider.AESCipher.engineDoFinal(AESCipher.java:446)
at javax.crypto.Cipher.doFinal(Cipher.java:2165)
at aesencrypt.decryptText(aesencrypt.java:38)
at aesencrypt.main(aesencrypt.java:15)
我已经搜索了Stack Overflow和搜索引擎,但实际上找不到解决方案。
更新 :已解决问题,感谢JB Nizet提供了解决方案!
修改后的代码:
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.xml.bind.DatatypeConverter;
public class aesencrypt {
public static void main(String[] args) throws Exception {
String plainText = "Hello World";
System.out.println("Original Text:" + plainText);
SecretKey secKey = getSecretEncryptionKey();
System.out.println("AES Key (Hex Form):"+bytesToHex(secKey.getEncoded()));
String encryptedText = bytesToHex(encryptText(plainText, secKey));
System.out.println("Encrypted Text (Hex Form):"+encryptedText);
String decryptedText = decryptText(encryptedText, secKey);
System.out.println("Decrypted Text:"+decryptedText);
}
public static SecretKey getSecretEncryptionKey() throws Exception{
KeyGenerator generator = KeyGenerator.getInstance("AES");
generator.init(128);
SecretKey secKey = generator.generateKey();
return secKey;
}
public static byte[] encryptText(String plainText,SecretKey secKey) throws Exception{
Cipher aesCipher = Cipher.getInstance("AES");
aesCipher.init(Cipher.ENCRYPT_MODE, secKey);
byte[] byteCipherText = aesCipher.doFinal(plainText.getBytes());
return byteCipherText;
}
public static String decryptText(String encrypted, SecretKey secKey) throws Exception {
Cipher aesCipher = Cipher.getInstance("AES");
aesCipher.init(Cipher.DECRYPT_MODE, secKey);
byte[] bytePlainText = aesCipher.doFinal(hexToByte(encrypted));
return new String(bytePlainText);
}
private static String bytesToHex(byte[] hash) {
return DatatypeConverter.printHexBinary(hash);
}
private static byte[] hexToByte(String txt) {
return DatatypeConverter.parseHexBinary(txt);
}
}
这是输出:
Original Text:Hello World
AES Key (Hex Form):84526F32BEDDBEA5BFBCDE241AD9BBA2
Encrypted Text (Hex Form):25378032E5F52575B7CEF311D45F00BD
Decrypted Text:Hello World
看你在做什么:
String encryptedText = bytesToHex(encryptText(plainText, secKey));
在这里,您将纯文本转换为字节(使用有损,与平台有关的getBytes()
,顺便说一句。您应该使用UTF8)。
然后,您将这些字节加密并得到一个字节数组。 然后,您将此字节数组编码为十六进制。
因此,相反的操作将是:从十六进制解码为字节,然后解密那些字节,然后从解密后的字节构造一个字符串。
但是,这是您正在做的事情:
String decryptedText = decryptText(encryptedText, secKey);
其中deleteText()的作用是:
byte[] bytePlainText = aesCipher.doFinal(encrypted.getBytes());
因此,您永远不会使用十六进制解码。 如果你使用bytesToHex()
在一边,你需要使用hexToBytes()
的另一边。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.