Here an image file is encrypted and decrypted using another image file as the password
/* EncryptFile.java */
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
/**
*
* @author dhanoopbhaskar
*/
public class EncryptFile {
SecretKey secretKey = null;
Cipher cipher = null;
String filePath = null;
public EncryptFile(String filePath) {
this.filePath = filePath;
try {
/**
* Create a Blowfish key
*/
byte[] password = getPasswordFromFile(filePath);
if (password == null) {
System.out.println("Unable to read the password file!");
System.exit(0);
}
secretKey = new SecretKeySpec(password, "Blowfish");
/**
* Create an instance of cipher mentioning the name of algorithm
* - Blowfish
*/
cipher = Cipher.getInstance("Blowfish");
} catch (NoSuchPaddingException ex) {
System.out.println(ex);
} catch (NoSuchAlgorithmException ex) {
System.out.println(ex);
}
}
/**
*
* @param filePath
* @return password
*
* Encrypts the file in srcPath and creates a file in destPath
*/
private byte[] getPasswordFromFile(String filePath) {
File file = new File(filePath);
InputStream inStream;
/**
* maximum allowable key size for blowfish is 56 bytes,
* but java supports only upto 16 bytes.
*/
byte[] buffer = new byte[16];
try {
inStream = new FileInputStream(file);
int len = inStream.read(buffer);
if (len <= 0) buffer = null;
} catch (FileNotFoundException ex) {
System.out.println(ex);
} catch (IOException ex) {
System.out.println(ex);
}
return buffer;
}
public static void main(String[] args) {
String fileToEncrypt = "fileToEncrypt.jpg";
String encryptedFile = "encryptedFile.jpg";
String decryptedFile = "decryptedFile.jpg";
String directoryPath = "/home/dhanoopbhaskar/Desktop/blowfish/";
String passwordFile = "password.jpg";
EncryptFile encryptFile = new EncryptFile(directoryPath + passwordFile);
System.out.println("Starting Encryption...");
encryptFile.encrypt(directoryPath + fileToEncrypt,
directoryPath + encryptedFile);
System.out.println("Encryption completed...");
encryptFile = new EncryptFile(directoryPath + passwordFile);
System.out.println("Starting Decryption...");
encryptFile.decrypt(directoryPath + encryptedFile,
directoryPath + decryptedFile);
System.out.println("Decryption completed...");
}
/**
*
* @param srcPath
* @param destPath
*
* Encrypts the file in srcPath and creates a file in destPath
*/
private void encrypt(String srcPath, String destPath) {
File rawFile = new File(srcPath);
File encryptedFile = new File(destPath);
InputStream inStream = null;
OutputStream outStream = null;
try {
/**
* Initialize the cipher for encryption
*/
cipher.init(Cipher.ENCRYPT_MODE, secretKey);
/**
* Initialize input and output streams
*/
inStream = new FileInputStream(rawFile);
outStream = new FileOutputStream(encryptedFile);
byte[] buffer = new byte[1024];
int len;
while ((len = inStream.read(buffer)) > 0) {
outStream.write(cipher.update(buffer, 0, len));
outStream.flush();
}
outStream.write(cipher.doFinal());
inStream.close();
outStream.close();
} catch (IllegalBlockSizeException ex) {
System.out.println(ex);
} catch (BadPaddingException ex) {
System.out.println(ex);
} catch (InvalidKeyException ex) {
System.out.println(ex);
} catch (FileNotFoundException ex) {
System.out.println(ex);
} catch (IOException ex) {
System.out.println(ex);
}
}
/**
*
* @param srcPath
* @param destPath
*
* Decrypts the file in srcPath and creates a file in destPath
*/
private void decrypt(String srcPath, String destPath) {
File encryptedFile = new File(srcPath);
File decryptedFile = new File(destPath);
InputStream inStream = null;
OutputStream outStream = null;
try {
/**
* Initialize the cipher for decryption
*/
cipher.init(Cipher.DECRYPT_MODE, secretKey);
/**
* Initialize input and output streams
*/
inStream = new FileInputStream(encryptedFile);
outStream = new FileOutputStream(decryptedFile);
byte[] buffer = new byte[1024];
int len;
while ((len = inStream.read(buffer)) > 0) {
outStream.write(cipher.update(buffer, 0, len));
outStream.flush();
}
outStream.write(cipher.doFinal());
inStream.close();
outStream.close();
} catch (IllegalBlockSizeException ex) {
System.out.println(ex);
} catch (BadPaddingException ex) {
System.out.println(ex);
} catch (InvalidKeyException ex) {
System.out.println(ex);
} catch (FileNotFoundException ex) {
System.out.println(ex);
} catch (IOException ex) {
System.out.println(ex);
}
}
}