我有一个任务，必须在CBC模式下强制使用AES-192加密的.enc文件。
因此，我要做的第一件事是尝试使用Java和Crypto库进行脱机字典攻击，问题在于字典中的平均单词长8位，因此密码必须以某种方式添加盐分。 问题是我编写的程序在每次执行时都会输出不同的密码，而输出只是无法读取的文本。
这是主要内容：
public class main {
public static void main(String[] args) {
bruteForceFile();
}
/*
* Tries to brute force the file reading all the possible keys from a dictionary
* */
private static void bruteForceFile() {
System.out.println("--------------------------------------------------------");
System.out.println("Starting brute force/dictionary attack:");
try {
byte[] file = cipherText.cipherText.getInstance().getFileArray();
bruteForceWrapper enc = new AES(OperatingMode.CBC).bruteForceFile(file);
System.out.println("decription succeded, key : " + enc.key + " elapsed time: " + enc.elapsedSeconds +"s");
System.out.println("--------------------------------------------------------");
System.out.println("Decripted message:\n");
System.out.println(new String(enc.data));
}catch(Exception e) {
e.printStackTrace();
}
}
}
这是AES类：
/**
*Advanced Encryption Standard as specified by NIST in FIPS 197. Also known as the Rijndael
*algorithm by Joan Daemen and Vincent Rijmen,
*AES is a 128-bit block cipher supporting keys of 128, 192, and 256 bits.
*/
public class AES extends cipher.AbstractCipher {
public AES(OperatingMode opm) {
super(opm);
super.enablePadding();
}
@Override
protected String getMode() {
if(opm == OperatingMode.CBC) {
if(padding)
return "AES/CBC/PKCS5Padding";
return "AES/CBC/NoPadding";
}
else {
if(padding)
return "AES/ECB/PKCS5Padding";
return "AES/ECB/NoPadding";
}
}
@Override
public encriptionWrapper encript(byte[] plainText,AbstractCipherKey key) {
return null;
}
@Override
public encriptionWrapper decript(byte[]cipherText,AbstractCipherKey key) {
StopWatch timer = new StopWatch();
if(super.print) {
System.out.println("------------------------------------------------------------");
System.out.println("Starting " + this.toString() + " decryption" + " in "
+ opm.toString() + " mode."+ " (" + this.getMode() + ")");
}
try {
Cipher dcipher = Cipher.getInstance("AES");
AESCipherKey aes_key = (AESCipherKey)key;
byte[] b_key = aes_key.getPassword().getBytes("UTF-8");
MessageDigest sha = MessageDigest.getInstance("SHA-1");
b_key = sha.digest(b_key);
b_key = Arrays.copyOf(b_key, 16);
SecretKeySpec secretKeySpec = new SecretKeySpec(b_key, "AES");
dcipher.init(Cipher.DECRYPT_MODE, secretKeySpec);// decode with base64 to get bytes
byte[] utf8 = dcipher.doFinal(cipherText);
// create new string based on the specified charset
if(super.print) {
System.out.println("Encryption ended. Elapsed Time: " + timer.getSeconds() + "s");
System.out.println("encrypted message length: " + utf8.length);
System.out.println("------------------------------------------------------------");
}
return new encriptionWrapper(utf8,timer.getSeconds());
} catch (Exception e) {
/*if(e.getClass() == BadPaddingException.class) {
System.out.println("attempt failed....");
}*/
if(super.print) {
System.out.println(this.toString() + " decryption failed. \n");
System.out.println("decryption ended. Elapsed Time: " + timer.getSeconds() + "s");
System.out.println("------------------------------------------------------------\n");
}
return null;
}
}
/*
* Try to brute force an encrypted file with AES
*/
public bruteForceWrapper bruteForceFile(byte[] encrypted) {
StopWatch watch = new StopWatch();
Dictionary dic = new Dictionary();
bruteForceWrapper wrapper;
super.print = false;
System.out.print("Decrypting...");
while(1 == 1) {
if(dic.getProvidedWords().size()%10 == 0) {
System.out.print(".");
}
encriptionWrapper enc = decript(encrypted,new AESCipherKey(dic.getWord()));
if(enc != null) {
wrapper = new bruteForceWrapper(enc.data, watch.getSeconds());
break;
}
}
super.print = true;
wrapper.tried_keys = dic.getProvidedWords();
wrapper.key = dic.getProvidedWords().get(dic.getProvidedWords().size() - 1);
return wrapper;
}
@Override
public String toString() {
return "AES";
}
}
最后是AESCipherKey类：
public class AESCipherKey extends AbstractCipherKey{
private String SHA_TEC = "SHA-1";
public AESCipherKey(String key) {
super(key);
}
/**
*Return the desription of the safeness of the key(unsafe is user generated)
*/
@Override
public String getKeySafenessDescription() {
if(isKeySafe) {
return "(safe key)";
}else
return "(unsafe key)";
}
@Override
public boolean validate() {
if(super.isKeySafe)
return true;
if(super.getByteArray().length != 16) {
System.out.println("Invalid AES key: " + super.key);
return false;
}
return true;
}
@Override
public void generateSecureKey() {
KeyGenerator keyGen;
try {
keyGen = KeyGenerator.getInstance("AES");
keyGen.init(256);
super.safeKey = keyGen.generateKey();
super.isKeySafe = true;
} catch (NoSuchAlgorithmException e) {
System.out.println("Error generating AES safe key");
e.printStackTrace();
}
}
public String getPassword() {
return super.key;
}
}
所以我认为问题就在这里：
byte[] b_key = aes_key.getPassword().getBytes("UTF-8");
MessageDigest sha = MessageDigest.getInstance("SHA-1");
b_key = sha.digest(b_key);
b_key = Arrays.copyOf(b_key, 16);
SecretKeySpec secretKeySpec = new SecretKeySpec(b_key, "AES");
但是我找不到错误，这里是解密的一些输出：
--------------------------------------------------------
Starting brute force/dictionary attack:
Decrypting................decription succeded, key : enantiopathia elapsed time: 12.995s
--------------------------------------------------------
Decripted message:
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�/���*���"sK���*[U�ɮ�����s��ec�P��z�6v�����Ov��1e����w�5����t�{s�%���|��W���'�3�^�H�Td��k1���S���l�8��Žѕ���XZ�X�Eiq��K���|�'�Wi��
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