This is a sample code through which I'm trying to read a file and encrypt/decrypt (if key is known for correct decryption) problem is the code is locked to accept the key of length 8, anything above or below is issuing a runtime error stating :
Exception in thread "main" java.security.InvalidKeyException: Invalid key length: 11 bytes
at com.sun.crypto.provider.DESCipher.engineGetKeySize(DESCipher.java:373)
at javax.crypto.Cipher.passCryptoPermCheck(Cipher.java:1052)
at javax.crypto.Cipher.checkCryptoPerm(Cipher.java:1010)
at javax.crypto.Cipher.implInit(Cipher.java:786)
at javax.crypto.Cipher.chooseProvider(Cipher.java:849)
at javax.crypto.Cipher.init(Cipher.java:1213)
at javax.crypto.Cipher.init(Cipher.java:1153)
at custom_enc.Custom_enc.encrypt(Custom_enc.java:50)
at custom_enc.Custom_enc.main(Custom_enc.java:105)
Java Result: 1
Class:
package custom_enc;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.Scanner;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.spec.SecretKeySpec;
public class Custom_enc {
String ekey="";
String algorithm="";
String path1="";
File f;
public void Custom_enc()
{
System.out.println("Enter the file name with extension and path : \n");
Scanner s = new Scanner(System.in);
String path1 = s.nextLine();
f = new File(path1);
System.out.println("Enter secret key : \n");
ekey = s.nextLine();
}
public void encrypt() throws Exception
{
Custom_enc();
this.algorithm="DES/ECB/PKCS5Padding";
FileInputStream fis =new FileInputStream(f);
f=new File(f.getAbsolutePath()+"_encrypted_file.txt");
FileOutputStream fos =new FileOutputStream(f);
byte k[] = ekey.getBytes();
SecretKeySpec key = new SecretKeySpec(k,"DES");
Cipher encrypt = Cipher.getInstance(algorithm);
encrypt.init(Cipher.ENCRYPT_MODE, key);
CipherOutputStream cout=new CipherOutputStream(fos, encrypt);
byte[] buf = new byte[1024];
int read;
while((read=fis.read(buf))!=-1) //reading data
cout.write(buf,0,read); //writing encrypted data
fis.close();
cout.flush();
cout.close();
System.out.println("Encryption Done!!");
//exit();
}
public void decrypt() throws Exception
{
Custom_enc();
this.algorithm="DES/ECB/PKCS5Padding";
FileInputStream fis =new FileInputStream(f);
f=new File(f.getAbsolutePath()+"_decrypted_file.txt");
FileOutputStream fos =new FileOutputStream(f);
byte k[] = ekey.getBytes();
SecretKeySpec key = new SecretKeySpec(k,"DES");
Cipher decrypt = Cipher.getInstance(algorithm);
decrypt.init(Cipher.DECRYPT_MODE, key);
CipherInputStream cin=new CipherInputStream(fis, decrypt);
byte[] buf = new byte[1024];
int read=0;
while((read=cin.read(buf))!=-1) //reading encrypted data
{
fos.write(buf,0,read); //writing decrypted data
}
cin.close();
fos.flush();
fos.close();
System.out.println("Encryption Done!!");
//1exit();
}
public static void main(String[] args) throws Exception, java.security.InvalidKeyException {
Custom_enc obj = new Custom_enc();
System.out.println("Enter your choice : \n 1 For Encryption \n 2 For Decryption");
Scanner s1 = new Scanner(System.in);
int choice = s1.nextInt();
if(choice==1)
{
System.out.println("You've chosen to Encrypt\n");
obj.encrypt();
}
else if(choice==2)
{
System.out.println("You've chosen to Decrypt\n");
obj.decrypt();
}
else
{
System.out.println("Invalid Choice, Try again...");
}
}
}
