FileEncryption

[Anne_J]

Ole!

Estoy desesperada con un tema del "FileEncryption", es una tonteria lo que me queda, pero no lo consigo...He encontrado este fichero que encripta/desencripta.

openssl genrsa -out private.pem 2048

To get it into the required (PKCS#8, DER) format:
openssl pkcs8 -topk8 -in private.pem -outform DER -out private.der -nocrypt

To generate a public key from the private key:
openssl rsa -in private.pem -pubout -outform DER -out public.der

An example of how to use the code:
FileEncryption secure = new FileEncryption();

// to encrypt a file
secure.makeKey();
secure.saveKey(encryptedKeyFile, publicKeyFile);
secure.encrypt(fileToEncrypt, encryptedFile);

// to decrypt it again
secure.loadKey(encryptedKeyFile, privateKeyFile);
secure.decrypt(encryptedFile, unencryptedFile);


¿¿¿¿¿¿¿Qué tipo de fichero es "encryptedKeyFile????????¿¿Qué extensión le pongo???? he probado con .key, .pem, sin extensión etc.. y siempre me da el error "invalid key format"...ayudadme plisssssssssss

Código:

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.*;
import java.security.spec.*;

import javax.crypto.*;
import javax.crypto.spec.*;


public class FileEncryption {
	
	private static final int AES_Key_Size = 256;
	
	Cipher pkCipher, aesCipher;
	byte[] aesKey;
	SecretKeySpec aeskeySpec;
	
	/**
	 * Constructor: creates ciphers
	 */
	public FileEncryption() throws GeneralSecurityException {
            Provider sunjce = new com.sun.crypto.provider.SunJCE();
            Security.addProvider(sunjce);
            // create RSA public key cipher
            pkCipher = Cipher.getInstance("RSA");
	    // create AES shared key cipher
	    aesCipher = Cipher.getInstance("AES");
	}
	
	/**
	 * Creates a new AES key
	 */
	public void makeKey() throws NoSuchAlgorithmException {

            KeyGenerator kgen = KeyGenerator.getInstance("AES");
	    kgen.init(AES_Key_Size);
	    SecretKey key = kgen.generateKey();
	    aesKey = key.getEncoded();
	    aeskeySpec = new SecretKeySpec(aesKey, "AES");
	}

	/**
	 * Decrypts an AES key from a file using an RSA private key
	 */
	public void loadKey(File in, File privateKeyFile) throws GeneralSecurityException, IOException {
		// read private key to be used to decrypt the AES key
		byte[] encodedKey = new byte[(int)privateKeyFile.length()];
		new FileInputStream(privateKeyFile).read(encodedKey);
		
		// create private key
		PKCS8EncodedKeySpec privateKeySpec = new PKCS8EncodedKeySpec(encodedKey);
		KeyFactory kf = KeyFactory.getInstance("RSA");
		PrivateKey pk = kf.generatePrivate(privateKeySpec);
		
		// read AES key
		pkCipher.init(Cipher.DECRYPT_MODE, pk);
		aesKey = new byte[AES_Key_Size/8];
		CipherInputStream is = new CipherInputStream(new FileInputStream(in), pkCipher);
		is.read(aesKey);
		aeskeySpec = new SecretKeySpec(aesKey, "AES");
                System.out.println("Private AES key loaded.");
	}
	
	/**
	 * Encrypts the AES key to a file using an RSA public key
	 */
	public void saveKey(File out, File publicKeyFile) throws IOException, GeneralSecurityException {
		// read public key to be used to encrypt the AES key
		byte[] encodedKey = new byte[(int)publicKeyFile.length()];
		new FileInputStream(publicKeyFile).read(encodedKey);
		
		// create public key
		X509EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(encodedKey);
		KeyFactory kf = KeyFactory.getInstance("RSA");
		PublicKey pk = kf.generatePublic(publicKeySpec);
		
		// write AES key
		pkCipher.init(Cipher.ENCRYPT_MODE, pk);
		CipherOutputStream os = new CipherOutputStream(new FileOutputStream(out), pkCipher);
		os.write(aesKey);
                System.out.println("Written AES key " + new String(aesKey));
		os.close();
	}
	
	/**
	 * Encrypts and then copies the contents of a given file.
	 */
	public void encrypt(File in, File out) throws IOException,
                            InvalidKeyException,
                            NoSuchAlgorithmException, 
                            NoSuchPaddingException {

            // aesCipher = Cipher.getInstance("AES");
            aesCipher.init(Cipher.ENCRYPT_MODE, aeskeySpec);

            FileInputStream is = new FileInputStream(in);
            CipherOutputStream os = new CipherOutputStream(new FileOutputStream(out), aesCipher);

            Long fileLength = in.length();
            System.out.println("File to encrypt: " + in.getName() + "; length: " + fileLength.toString() + " bytes.");

            copy(is, os);
            os.close();
            System.out.println("Encryption performed. Output in " + out.getAbsolutePath());
	}
	
	/**
	 * Decrypts and then copies the contents of a given file.
	 */
	public void decrypt(File in, File out) throws IOException, InvalidKeyException {
		aesCipher.init(Cipher.DECRYPT_MODE, aeskeySpec);

                Long fileLength;

		CipherInputStream is = new CipherInputStream(new FileInputStream(in), aesCipher);
		FileOutputStream os = new FileOutputStream(out);
		
		copy(is, os);
		
		is.close();
		os.close();

                fileLength = out.length();
                System.out.println("New file decrypted: " + out.getAbsolutePath() + "; length: " + fileLength.toString() + " bytes.");
	}
	
	/**
	 * Copies a stream.
	 */
	private void copy(InputStream is, OutputStream os) throws IOException {
		int i;
		byte[] b = new byte[1024];
		while((i=is.read(b))!=-1) {
			os.write(b, 0, i);
		}
	}
}