// Copyright (C) 2002 IAIK
// https://sic.tech/
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// Copyright (C) 2003 - 2025 Stiftung Secure Information and 
//                           Communication Technologies SIC
// https://sic.tech/
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// $Header: /IAIK-CMS/current/src/demo/cms/envelopedData/CAST128EnvelopedDataDemo.java 21    12.02.25 17:58 Dbratko $
// $Revision: 21 $
//

package demo.cms.envelopedData;

import iaik.asn1.INTEGER;
import iaik.asn1.OCTET_STRING;
import iaik.asn1.ObjectID;
import iaik.asn1.SEQUENCE;
import iaik.asn1.structures.AlgorithmID;
import iaik.cms.CMSException;
import iaik.cms.EncryptedContentInfoStream;
import iaik.cms.EnvelopedDataStream;
import iaik.cms.KeyTransRecipientInfo;
import iaik.cms.RecipientInfo;
import iaik.cms.SecurityProvider;
import iaik.security.random.SecRandom;
import iaik.utils.Util;
import iaik.x509.X509Certificate;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.SecureRandom;
import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;

import demo.DemoUtil;
import demo.keystore.CMSKeyStore;

/**
 * This class demonstrates the EnvelopedDataStream/EncryptedContentInfoStream usages
 * for the CAST128 algorithm.
 * <p>
 * This demo compares the usage of class EnvelopedDataStream for encrypting the content
 * using CAST128 with automatical (transparent) key/parameter handling against explicit
 * key/parameter/EncrypedContentInfoStream handling.
 * <p>
 * All keys and certificates are read from a keystore created by the
 * SetupCMSKeyStore program.
 * <p>
 * CAST parameters are defined as:
 * <pre>
 * Parameters ::=  SEQUENCE {
 *   iv         OCTET STRING DEFAULT 0,
 *   keyLength  INTEGER }
 * </pre>
 */
public class CAST128EnvelopedDataDemo {

  // certificate of user 1
  X509Certificate user1;
  // private key of user 1
  PrivateKey user1_pk;
  // certificate of user 2
  X509Certificate user2;
  // private key of user 2
  PrivateKey user2_pk;
  // secure random number generator
  SecureRandom random;
  
  /**
   * Setup the demo certificate chains.
   *
   * Keys and certificate are retrieved from the demo KeyStore.
   *
   * @throws IOException if an file read error occurs
   */
  public CAST128EnvelopedDataDemo() throws IOException {
    
    System.out.println();
    System.out.println("**********************************************************************************");
    System.out.println("*                          CAST128EnvelopedDataDemo                              *");
    System.out.println("*      (shows the usage of the EnvelopedData type for the CAST128 cipher)        *");
    System.out.println("**********************************************************************************");
    System.out.println();
    // add all certificates to the list
    X509Certificate[] certs = CMSKeyStore.getCertificateChain(CMSKeyStore.RSA, CMSKeyStore.SZ_2048_CRYPT_1);
    user1 = certs[0];
    user1_pk = CMSKeyStore.getPrivateKey(CMSKeyStore.RSA, CMSKeyStore.SZ_2048_CRYPT_1);
    user2 = CMSKeyStore.getCertificateChain(CMSKeyStore.RSA, CMSKeyStore.SZ_2048_CRYPT_2)[0];
    user2_pk = CMSKeyStore.getPrivateKey(CMSKeyStore.RSA, CMSKeyStore.SZ_2048_CRYPT_2);
    
    random = SecRandom.getDefault();
  }
  
  /**
   * Creates a CMS <code>EnvelopedDataStream</code> message.
   * <p>
   *
   * @param message the message to be enveloped, as byte representation
   * @param contentEA the content encryption algorithm
   * @param keyLength the key length for the symmetric key
   * @return the DER encoding of the <code>EnvelopedData</code> object just created
   * @throws Exception if the <code>EnvelopedData</code> object cannot
   *                          be created
   */
  public byte[] createEnvelopedDataStream(byte[] message, AlgorithmID contentEA, int keyLength) throws Exception {

    EnvelopedDataStream enveloped_data;

    // we are testing the stream interface
    ByteArrayInputStream is = new ByteArrayInputStream(message);
    // create a new EnvelopedData object 
    try {
      enveloped_data = new EnvelopedDataStream(is, contentEA, keyLength);
    } catch (NoSuchAlgorithmException ex) {
      throw new CMSException("No implementation for contentEA.getAlgorithm().getName().");
    }


    // create the recipient infos
    RecipientInfo[] recipients = new RecipientInfo[2];
    // user1 is the first receiver
    recipients[0] = new KeyTransRecipientInfo(user1, (AlgorithmID)AlgorithmID.rsaEncryption.clone());
    // user2 is the second receiver
    recipients[1] = new KeyTransRecipientInfo(user2, (AlgorithmID)AlgorithmID.rsaEncryption.clone());
    // specify the recipients of the encrypted message
    enveloped_data.setRecipientInfos(recipients);

    // return the EnvelopedDate as DER encoded byte array with block size 2048
    ByteArrayOutputStream os = new ByteArrayOutputStream();
    enveloped_data.writeTo(os, 2048);
    return os.toByteArray();
  }



  /**
   * Creates a CMS <code>EnvelopedDataStream</code> message.
   * <p>
   * Keys and parameters, and EncryptedContentInfoStream are created outside
   * the EnvelopedDataStream class.
   *
   * @param message the message to be enveloped, as byte representation
   * @param cea the content encryption algorithm
   * @param keyLength the key length for the symmetric key
   * @return the DER encoding of the <code>EnvelopedData</code> object just created
   * @throws Exception if the <code>EnvelopedData</code> object cannot
   *                          be created
   */
  public byte[] createEncryptedContentInfoStream(byte[] message, AlgorithmID cea, int keyLength) throws Exception {
       
    AlgorithmID contentEA = (AlgorithmID)cea.clone(); 
    ByteArrayInputStream is = new ByteArrayInputStream(message);
    
    // generate parameters (iv and key length)
    // create iv
    byte[] iv = new byte[8];
    random.nextBytes(iv);
    SEQUENCE parameter = new SEQUENCE();
    parameter.addComponent(new OCTET_STRING(iv));
    parameter.addComponent(new INTEGER(keyLength));
    contentEA.setParameter(parameter);
    AlgorithmParameterSpec params = new IvParameterSpec(iv);

    // generate the content encryption key
    KeyGenerator keyGen = SecurityProvider.getSecurityProvider().getKeyGenerator(contentEA, keyLength);
    // generate a new key
    SecretKey secretKey = keyGen.generateKey();

    // create the EncryptedContentInfo for the content to be encrypted
    EncryptedContentInfoStream eci = new EncryptedContentInfoStream(ObjectID.cms_data, is);
    // setup the cipher for encryption
    eci.setupCipher(contentEA, secretKey, params);

    // create the recipient infos
    RecipientInfo[] recipients = new RecipientInfo[2];
    // user1 is the first receiver
    recipients[0] = new KeyTransRecipientInfo(user1, (AlgorithmID)AlgorithmID.rsaEncryption.clone());
    // encrypt the secret key for recipient 1
    recipients[0].encryptKey(secretKey);
    // user2 is the second receiver
    recipients[1] = new KeyTransRecipientInfo(user2, (AlgorithmID)AlgorithmID.rsaEncryption.clone());
    // encrypt the secret key for recipient 2
    recipients[1].encryptKey(secretKey);
    // now create the EnvelopedDataStream
    EnvelopedDataStream enveloped_data = new EnvelopedDataStream(recipients, eci);

    // return the EnvelopedDate as DER encoded byte array with block size 2048
    ByteArrayOutputStream os = new ByteArrayOutputStream();
    enveloped_data.writeTo(os, 2048);
    byte[] enc = os.toByteArray();
    return enc;
  }

  /**
   * Decrypts the encrypted content of the given <code>EnvelopedData</code> object for the
   * specified recipient and returns the decrypted (= original) message.
   * <p>
   * Decryption and cipher setup and EncryptedContentInfoStrean processing 
   * is performed outside class EnvelopedDataStream.
   *
   * @param encoding the <code>EnvelopedData</code> object as DER encoded byte array
   * @param privateKey the private key to decrypt the message
   * @param recipientInfoIndex the index into the <code>RecipientInfo</code> array
   *                           to which the specified private key belongs
   *
   * @return the recovered message, as byte array
   * @throws CMSException if the message cannot be recovered
   */
  public byte[] getEncryptedContentInfoStream(byte[] encoding, PrivateKey privateKey, int recipientInfoIndex) throws Exception {

    // create the EnvelopedData object from a DER encoded byte array
    // we are testing the stream interface
    ByteArrayInputStream is = new ByteArrayInputStream(encoding);
    EnvelopedDataStream enveloped_data = new EnvelopedDataStream(is);

    // get the recipient infos
    RecipientInfo[]  recipients = enveloped_data.getRecipientInfos();

    System.out.println("\nThis message can be decrypted by the owners of the following certificates:");

    for (int i=0; i<recipients.length; i++) {
      System.out.println("Recipient "+(i+1)+":");
      System.out.println(recipients[i].getRecipientIdentifiers()[0]);
    }
    // decrypt symmetric content encryption key, e.g.:
    SecretKey secretKey = recipients[recipientInfoIndex].decryptKey(user1_pk);

    //get the ECI from the enveloped data:
    EncryptedContentInfoStream eci = (EncryptedContentInfoStream)enveloped_data.getEncryptedContentInfo();
    System.out.println("\nContent type of encrypted data: " + eci.getContentType());
    //get the content encryption algorithm:
    AlgorithmID contentEA = eci.getContentEncryptionAlgorithm();
    System.out.println("Content Encryption Algorithm: " + contentEA);
    
    // get the parameters as SEQUENCE
    SEQUENCE seq = (SEQUENCE)contentEA.getParameter();
    // the iv is the first component
    OCTET_STRING oct = (OCTET_STRING)seq.getComponentAt(0);
    AlgorithmParameterSpec params = new IvParameterSpec((byte[])oct.getValue());

    //now setup the cipher with previously decrypted recipient key amd params
    eci.setupCipher(secretKey, params);
    //get and read the data thereby actually performing the decryption
    InputStream data_is = eci.getInputStream();
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    Util.copyStream(data_is, baos, null);
    byte[] decrypted = baos.toByteArray();
    return decrypted;
  }
  
  /**
   * Decrypts the encrypted content of the given <code>EnvelopedData</code> object for the
   * specified recipient and returns the decrypted (= original) message.
   *
   * @param encoding the <code>EnvelopedData</code> object as DER encoded byte array
   * @param privateKey the private key to decrypt the message
   * @param recipientInfoIndex the index into the <code>RecipientInfo</code> array
   *                           to which the specified private key belongs
   *
   * @return the recovered message, as byte array
   * @throws Exception if the message cannot be recovered
   */
  public byte[] getEnvelopedDataStream(byte[] encoding, PrivateKey privateKey, int recipientInfoIndex) throws Exception {

    // create the EnvelopedData object from a DER encoded byte array
    // we are testing the stream interface
    ByteArrayInputStream is = new ByteArrayInputStream(encoding);
    EnvelopedDataStream enveloped_data = new EnvelopedDataStream(is);

    // get the recipient infos
    RecipientInfo[]  recipients = enveloped_data.getRecipientInfos();

    System.out.println("\nThis message can be decrypted by the owners of the following certificates:");

    for (int i=0; i<recipients.length; i++) {
      System.out.println("Recipient "+(i+1)+": ");
      System.out.println(recipients[i].getRecipientIdentifiers()[0]);
    }
    
    EncryptedContentInfoStream eci = enveloped_data.getEncryptedContentInfo();
    System.out.println("\nContent type of encrypted data: " + eci.getContentType());
    //get the content encryption algorithm:
    AlgorithmID contentEA = eci.getContentEncryptionAlgorithm();
    System.out.println("Content Encryption Algorithm: " + contentEA);
    //now setup the cipher with previously decrypted recipient key amd params
    enveloped_data.setupCipher(privateKey, recipientInfoIndex);
    //get and read the data thereby actually performing the decryption
    InputStream data_is = enveloped_data.getInputStream();
    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    Util.copyStream(data_is, baos, null);
    byte[] decrypted = baos.toByteArray();
    return decrypted;

  }

  
  
  /**
   * Starts the test.
   */
  public void start() {
     // the test message
    String m = "This is the test message.";
    System.out.println("Test message: "+m);
    System.out.println();
    byte[] message = m.getBytes();

    try {
      byte[] data;
      byte[] received_message = null;


      // the stream implementation
      //
      // test CMS EnvelopedDataStream
      //

      System.out.println("\nEnvelopedDataStream demo for algorithm CAST [create]:\n");
      data = createEnvelopedDataStream(message, (AlgorithmID)AlgorithmID.cast5_CBC.clone(), 128);

      // transmit data
      System.out.println("\nEnvelopedDataStream demo [parse]:\n");
      // user1 means index 0 (hardcoded for this demo)
      received_message = getEnvelopedDataStream(data, user1_pk, 0);
      //received_message = getEnvelopedDataStream(data, user2_pk, 1);
      System.out.print("\nDecrypted content: ");
      System.out.println(new String(received_message));

      // test against EncryptedContentInfoStream - EnvelopedDataStream creation

      System.out.println("\nEnvelopedDataStream demo for algorithm CAST [create]:\n");
      
      System.out.println("Create EncryptedContentInfo for EnvelopedData...");
      data = createEncryptedContentInfoStream(message, (AlgorithmID)AlgorithmID.cast5_CBC.clone(), 128);
      // transmit data
      System.out.println("\nEnvelopedDataStream demo [parse]:\n");
      // user1 means index 0 (hardcoded for this demo)
      received_message = getEnvelopedDataStream(data, user1_pk, 0);
      System.out.print("\nDecrypted content: ");
      System.out.println(new String(received_message));
      
      System.out.println("\nEnvelopedDataStream demo for algorithm CAST [create]:\n");
      data = createEnvelopedDataStream(message, (AlgorithmID)AlgorithmID.cast5_CBC.clone(), 128);
      // transmit data
   
      System.out.println("\nEnvelopedDataStream demo [parse]:\n");
      // user1 means index 0 (hardcoded for this demo)
      System.out.println("Decrypt EncryptedContentInfo of EnvelopedData...");
      received_message = getEncryptedContentInfoStream(data, user1_pk, 0);
      System.out.print("\nDecrypted content: ");
      System.out.println(new String(received_message));
     
  
        } catch (Exception ex) {
          ex.printStackTrace();
          throw new RuntimeException(ex.toString());
        }
  }

  /**
   * The main method.
   *
   * @throws Exception
   *            if some error occurs
   */
  public static void main(String argv[]) throws Exception {

        demo.DemoUtil.initDemos();

    (new CAST128EnvelopedDataDemo()).start();
    System.out.println("\nReady!");
    DemoUtil.waitKey();
  }
}