Criptografia usando Bouncy Castle

public void criptografarArquivo(File arquivo, PublicKey chavePublica) 
	throws CSFException, NoSuchProviderException, InvalidAlgorithmParameterException {
		//
		try {		
			
			Mac mac = Mac.getInstance("HMACSHA1","BC");
			
			
			chavePublica.hashCode();
			
			SecureRandom    sec_rand = new SecureRandom();
			byte[]  mac_key_bytes = new byte[20]; // Set to correct length for HMACSHA1
			sec_rand.nextBytes(mac_key_bytes); // Fill with random data,
			
			
			
			Key mac_key = new SecretKeySpec(mac_key_bytes, "HMACSHA1"); // Convert to key object.
			mac.init(mac_key); // Initialize.
			
			
			KeyGenerator key_gen = KeyGenerator.getInstance("AES", "BC"); // Using appropriate key generator.
			key_gen.init(128, sec_rand); // Set up with key size and a SecureRandom.
			Key aes_key = key_gen.generateKey(); // Generate the Key Object.
			
			byte[]		    ivBytes = new byte[] { 
					0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 
					0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f };
			
			//byte[]		    keyBytes = chavePublica.getEncoded();
			
			//SecretKeySpec   key = new SecretKeySpec(keyBytes, "AES");
			
			IvParameterSpec ivSpec = new IvParameterSpec(ivBytes);			 
			
			Cipher          cipher = Cipher.getInstance("AES/CBC/PKCS7Padding", "BC");
			
			cipher.init(Cipher.ENCRYPT_MODE, aes_key, ivSpec);
			
			byte [] arquivoEmBytes = UtilArquivos.abrirArquivoEmArrayDeBytes(arquivo);			
			
			byte [] arquivoCriptografado = null;
			
			arquivoCriptografado = cipher.doFinal(arquivoEmBytes);			
			
			File arqCripto = new File(arquivo.getAbsolutePath()+".p7b");
			
			FileOutputStream fos = new FileOutputStream(arqCripto);
			
			fos.write(arquivoCriptografado);
			
			fos.close();
			
		} catch (NoSuchAlgorithmException e) {
			
			throw new CSFExceptionCritica(e.getMessage(),e.getStackTrace());
			
		} catch (NoSuchPaddingException e) {
			
			throw new CSFExceptionCritica(e.getMessage(),e.getStackTrace());
			
		} catch (InvalidKeyException e) {
			
			throw new CSFExceptionCritica(e.getMessage(),e.getStackTrace());
			
		} catch (IOException e) {
			
			throw new CSFExceptionCritica(e.getMessage(),e.getStackTrace());
			
		} catch (IllegalBlockSizeException e) {
			
			throw new CSFExceptionCritica(e.getMessage(),e.getStackTrace());
			
		} catch (BadPaddingException e) {
			
			throw new CSFExceptionCritica(e.getMessage(),e.getStackTrace());
			
		} 
	}

/**
 * Demonstrate creation and processing a public key recipient enveloped-message
 * with matching of the RID to a certificate to make sure we have the right recipient.
 */
public class KeyTransEnvelopedDataWithCertMatchExample
{
    public static void main(String[] args)
        throws Exception
    {
        KeyStore        credentials = Utils.createCredentials();
        PrivateKey      key = (PrivateKey)credentials.getKey(Utils.END_ENTITY_ALIAS, Utils.KEY_PASSWD);
        Certificate[]   chain = credentials.getCertificateChain(Utils.END_ENTITY_ALIAS);
        X509Certificate cert = (X509Certificate)chain[0];

        // set up the generator
        CMSEnvelopedDataGenerator gen = new CMSEnvelopedDataGenerator();
        
        gen.addKeyTransRecipient(cert);
        
        // create the enveloped-data object
        CMSProcessable   data = new CMSProcessableByteArray("Hello World!".getBytes());

        CMSEnvelopedData enveloped = gen.generate(
                                data,
                                CMSEnvelopedDataGenerator.AES256_CBC, "BC");
        
        // recreate
        enveloped = new CMSEnvelopedData(enveloped.getEncoded());
        
        // set up to iterate through the recipients
        RecipientInformationStore   recipients = enveloped.getRecipientInfos();
        CertStore                   certStore = CertStore.getInstance("Collection", new CollectionCertStoreParameters(Collections.singleton(cert)), "BC");
        Iterator                    it = recipients.getRecipients().iterator();
        RecipientInformation        recipient = null;
        
        while (it.hasNext())
        {
            recipient = (RecipientInformation)it.next();
            if (recipient instanceof KeyTransRecipientInformation)
            {
                // match the recipient ID
                Collection matches = certStore.getCertificates(recipient.getRID());
                
                if (!matches.isEmpty())
                {
                    // decrypt the data
                    byte[] recData = recipient.getContent(key, "BC");

                    // compare recovered data to the original data
                    if (Arrays.equals((byte[])data.getContent(), recData))
                    {
                        System.out.println("data recovery succeeded");
                        break;
                    }
                    else
                    {
                        System.out.println("data recovery failed");
                        break;
                    }
                }
            }
        }   
        
        if (recipient == null)
        {
            System.out.println("could not find a matching recipient");
        }
    }
}