import java.io.*; import java.io.IOException; import java.io.UnsupportedEncoding
ID: 3555184 • Letter: I
Question
import java.io.*;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.spec.AlgorithmParameterSpec;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;
import javax.crypto.*;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;
/**
* Encryption and Decryption of String data; PBE(Password Based Encryption and Decryption)
*
*/
public class CryptoUtil {
Cipher ecipher;
Cipher dcipher;
// 8-byte Salt
byte[] salt = {
(byte) 0xA9, (byte) 0x9B, (byte) 0xC8, (byte) 0x32,
(byte) 0x56, (byte) 0x35, (byte) 0xE3, (byte) 0x03
};
// Iteration count
int iterationCount = 19;
public CryptoUtil() {
}
/**
*
* @param secretKey Key used to encrypt data
* @param plainText Text input to be encrypted
* @return Returns encrypted text
* @throws java.security.NoSuchAlgorithmException
*
*/
public String encrypt(String secretKey, String plainText)
throws NoSuchAlgorithmException,
InvalidKeySpecException,
NoSuchPaddingException,
InvalidKeyException,
InvalidAlgorithmParameterException,
UnsupportedEncodingException,
IllegalBlockSizeException,
BadPaddingException{
//Key generation for enc and desc
KeySpec keySpec = new PBEKeySpec(secretKey.toCharArray(), salt, iterationCount);
SecretKey key = SecretKeyFactory.getInstance("PBEWithMD5AndDES").generateSecret(keySpec);
// Prepare the parameter to the ciphers
AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt, iterationCount);
//Enc process
ecipher = Cipher.getInstance(key.getAlgorithm());
ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);
String charSet="UTF-8";
byte[] in = plainText.getBytes(charSet);
byte[] out = ecipher.doFinal(in);
String encStr=new sun.misc.BASE64Encoder().encode(out);
return encStr;
}
/**
* @param secretKey Key used to decrypt data
* @param encryptedText encrypted text input to decrypt
* @return Returns plain text after decryption
*/
public String decrypt(String secretKey, String encryptedText)
throws NoSuchAlgorithmException,
InvalidKeySpecException,
NoSuchPaddingException,
InvalidKeyException,
InvalidAlgorithmParameterException,
UnsupportedEncodingException,
IllegalBlockSizeException,
BadPaddingException,
IOException{
//Key generation for enc and desc
KeySpec keySpec = new PBEKeySpec(secretKey.toCharArray(), salt, iterationCount);
SecretKey key = SecretKeyFactory.getInstance("PBEWithMD5AndDES").generateSecret(keySpec);
// Prepare the parameter to the ciphers
AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt, iterationCount);
//Decryption process; same key will be used for decr
dcipher=Cipher.getInstance(key.getAlgorithm());
dcipher.init(Cipher.DECRYPT_MODE, key,paramSpec);
byte[] enc = new sun.misc.BASE64Decoder().decodeBuffer(encryptedText);
byte[] utf8 = dcipher.doFinal(enc);
String charSet="UTF-8";
String plainStr = new String(utf8, charSet);
return plainStr;
}
/*
public class MyFileOperations { */
public static void main(String[] args) throws Exception{
BufferedReader object = new BufferedReader
(new InputStreamReader(System.in));
CryptoUtil cryptoUtil=new CryptoUtil();
String key="ezeon8547";
String plain="Important Message read it before you proceed";
String enc=cryptoUtil.encrypt(key, plain);
System.out.println("0
Explanation / Answer
import java.io.*;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.spec.AlgorithmParameterSpec;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;
import javax.crypto.*;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;
import java.util.*;
import java.io.File;
import javax.swing.*;
/**
* Encryption and Decryption of String data; PBE(Password Based Encryption and Decryption)
*
*/
public class CryptoUtil {
Cipher ecipher;
Cipher dcipher;
// 8-byte Salt
byte[] salt = {
(byte) 0xA9, (byte) 0x9B, (byte) 0xC8, (byte) 0x32,
(byte) 0x56, (byte) 0x35, (byte) 0xE3, (byte) 0x03
};
// Iteration count
int iterationCount = 19;
public CryptoUtil() {
}
/**
*
* @param secretKey Key used to encrypt data
* @param plainText Text input to be encrypted
* @return Returns encrypted text
* @throws java.security.NoSuchAlgorithmException
*
*/
public String encrypt(String secretKey, String plainText)
throws NoSuchAlgorithmException,
InvalidKeySpecException,
NoSuchPaddingException,
InvalidKeyException,
InvalidAlgorithmParameterException,
UnsupportedEncodingException,
IllegalBlockSizeException,
BadPaddingException{
//Key generation for enc and desc
KeySpec keySpec = new PBEKeySpec(secretKey.toCharArray(), salt, iterationCount);
SecretKey key = SecretKeyFactory.getInstance("PBEWithMD5AndDES").generateSecret(keySpec);
// Prepare the parameter to the ciphers
AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt, iterationCount);
//Enc process
ecipher = Cipher.getInstance(key.getAlgorithm());
ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);
String charSet="UTF-8";
byte[] in = plainText.getBytes(charSet);
byte[] out = ecipher.doFinal(in);
String encStr=new sun.misc.BASE64Encoder().encode(out);
return encStr;
}
/**
* @param secretKey Key used to decrypt data
* @param encryptedText encrypted text input to decrypt
* @return Returns plain text after decryption
*/
public String decrypt(String secretKey, String encryptedText)
throws NoSuchAlgorithmException,
InvalidKeySpecException,
NoSuchPaddingException,
InvalidKeyException,
InvalidAlgorithmParameterException,
UnsupportedEncodingException,
IllegalBlockSizeException,
BadPaddingException,
IOException{
//Key generation for enc and desc
KeySpec keySpec = new PBEKeySpec(secretKey.toCharArray(), salt, iterationCount);
SecretKey key = SecretKeyFactory.getInstance("PBEWithMD5AndDES").generateSecret(keySpec);
// Prepare the parameter to the ciphers
AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt, iterationCount);
//Decryption process; same key will be used for decr
dcipher=Cipher.getInstance(key.getAlgorithm());
dcipher.init(Cipher.DECRYPT_MODE, key,paramSpec);
byte[] enc = new sun.misc.BASE64Decoder().decodeBuffer(encryptedText);
byte[] utf8 = dcipher.doFinal(enc);
String charSet="UTF-8";
String plainStr = new String(utf8, charSet);
return plainStr;
}
public static List<File> getSubdirs(File file) {
List<File> subdirs = Arrays.asList(file.listFiles(new FileFilter() {
public boolean accept(File f) {
return f.isDirectory();
}
}));
subdirs = new ArrayList<File>(subdirs);
List<File> deepSubdirs = new ArrayList<File>();
for(File subdir : subdirs) {
deepSubdirs.addAll(getSubdirs(subdir));
}
subdirs.addAll(deepSubdirs);
return subdirs;
}
/*
public class MyFileOperations { */
public static void main(String[] args) throws Exception{
BufferedReader object = new BufferedReader
(new InputStreamReader(System.in));
CryptoUtil cryptoUtil=new CryptoUtil();
String key="ezeon8547";
String plain="Important Message read it before you proceed";
String enc=cryptoUtil.encrypt(key, plain);
System.out.println("0
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