// Copyright (C) 2002 IAIK
// https://sic.tech/
//
// Copyright (C) 2003 - 2025 Stiftung Secure Information and 
//                           Communication Technologies SIC
// https://sic.tech/
//
// All rights reserved.
//
// This source is provided for inspection purposes and recompilation only,
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// be kept in strict confidence and must not be disclosed to any third party
// under any circumstances. Redistribution in source and binary forms, with
// or without modification, are <not> permitted in any case!
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// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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// $Header: /IAIK-CMS/current/src/demo/cms/ecc/ECDHAuthenticatedDataDemo.java 5     12.02.25 17:58 Dbratko $
// $Revision: 5 $
//


package demo.cms.ecc;

import iaik.asn1.ObjectID;
import iaik.asn1.structures.AlgorithmID;
import iaik.asn1.structures.Attribute;
import iaik.cms.AuthenticatedData;
import iaik.cms.AuthenticatedDataOutputStream;
import iaik.cms.AuthenticatedDataStream;
import iaik.cms.CMSException;
import iaik.cms.ContentInfo;
import iaik.cms.ContentInfoOutputStream;
import iaik.cms.ContentInfoStream;
import iaik.cms.IssuerAndSerialNumber;
import iaik.cms.KeyIdentifier;
import iaik.cms.OriginatorInfo;
import iaik.cms.RecipientInfo;
import iaik.cms.RecipientKeyIdentifier;
import iaik.cms.attributes.CMSContentType;
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.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;

import javax.crypto.SecretKey;

import demo.DemoUtil;

/**
 * Demonstrates the usage of class {@link iaik.cms.AuthenticatedDataStream}, 
 * {@link iaik.cms.AuthenticatedData} and {@link iaik.cms.AuthenticatedDataOutputStream}
 * for authenticated encrypting data using the CMS type
 * AuthenticatedData by using Static-Static ECDH according to <a href = 
 * "http://www.ietf.org/rfc/rfc6278.txt" target="_blank">6278</a> as 
 * key agreement method.
 * <p>
 * Any keys/certificates required for this demo are read from a keystore
 * file "cmsecc.keystore" located in your current working directory. If
 * the keystore file does not exist you can create it by running the
 * {@link demo.cms.ecc.keystore.SetupCMSEccKeyStore SetupCMSEccKeyStore}
 * program. 
 * <p>
 * Additionally to <code>iaik_cms.jar</code> you also must have 
 * <code>iaik_jce_(full).jar</code> (IAIK-JCE, <a href =
 * "https://sic.tech/products/core-crypto-toolkits/jca-jce/" target="_blank">
 * https://sic.tech/products/core-crypto-toolkits/jca-jce/</a>),
 * and <code>iaik_eccelarate.jar</code> (IAIK-ECCelerate<sup><small>TM</small></sup>, <a href =
 * "https://sic.tech/products/core-crypto-toolkits/eccelerate/" target="_blank">
 * https://sic.tech/products/core-crypto-toolkits/eccelerate/</a>)
 * in your classpath.
 *
 * @see iaik.cms.AuthenticatedDataStream
 * @see iaik.cms.AuthenticatedData
 * @see iaik.cms.AuthenticatedDataOutputStream
 * @see iaik.cms.RecipientInfo
 * @see iaik.cms.KeyAgreeRecipientInfo
 * @see demo.cms.ecc.keystore.SetupCMSEccKeyStore
 */
public class ECDHAuthenticatedDataDemo extends StaticStaticECDHDemo {

  /**
   * Setup the demo certificate chains.
   *
   * Keys and certificates are retrieved from the demo keyStore file
   * "cmsecc.keystore" located in your current working directory. If
   * the keystore file does not exist you can create it by running the
   * {@link demo.cms.ecc.keystore.SetupCMSEccKeyStore SetupCMSEccKeyStore}
   * program. 
   *
   * @throws IOException if keys/certificates cannot be read from the keystore
   */
  public ECDHAuthenticatedDataDemo() throws IOException {
    super();
    System.out.println();
    System.out.println("**********************************************************************************");
    System.out.println("*                          ECDH AuthenticatedData demo                           *");
    System.out.println("*   (shows the usage of the CMS AuthenticatedData type implementation for ECDH)  *");
    System.out.println("**********************************************************************************");
    System.out.println();
    
    
  }

  /**
   * Creates a CMS <code>AuthenticatedDataStream</code> for the given message message.
   *
   * @param message the message to be authenticated, as byte representation
   * @param macAlgorithm the mac algorithm to be used
   * @param macKeyLength the length of the temporary MAC key to be generated
   * @param digestAlgorithm the digest algorithm to be used to calculate a digest
   *                        from the content if authenticated attributes should
   *                        be included
   * @param mode whether to include the content into the AuthenticatedData ({@link
   *             AuthenticatedDataStream#IMPLICIT implicit}) or to not include it
   *             ({@link AuthenticatedDataStream#EXPLICIT explicit})
   *                                    
   * @return the BER encoding of the <code>AuthenticatedData</code> object just created
   * 
   * @throws CMSException if the <code>AuthenticatedData</code> object cannot
   *                          be created
   * @throws IOException if an I/O error occurs
   */
  public byte[] createAuthenticatedDataStream(byte[] message,
                                              AlgorithmID macAlgorithm,
                                              int macKeyLength,
                                              AlgorithmID digestAlgorithm,
                                              int mode)
    throws CMSException, IOException {
    
    AlgorithmID macAlg = (AlgorithmID)macAlgorithm.clone();
    AlgorithmID digestAlg = null;
    if (digestAlgorithm != null) {
       digestAlg = (AlgorithmID)digestAlgorithm.clone();
    }   
    ObjectID contentType = ObjectID.cms_data;
    
    AuthenticatedDataStream authenticatedData;

    // we are testing the stream interface
    ByteArrayInputStream is = new ByteArrayInputStream(message);
    // create a new AuthenticatedData object 
    try {
      authenticatedData = new AuthenticatedDataStream(contentType,
                                                      is, 
                                                      macAlg,
                                                      macKeyLength,
                                                      null,
                                                      digestAlg,
                                                      mode);
    } catch (NoSuchAlgorithmException ex) {
      throw new CMSException(ex.toString());
    }

    // static-static mode: set OriginatorInfo
    OriginatorInfo originator = new OriginatorInfo();
    originator.setCertificates(ecdhOriginatorCerts_);
    authenticatedData.setOriginatorInfo(originator);
    // create the recipient infos
    RecipientInfo[] recipients = createRecipients();
    // specify the recipients of the authenticated message
    authenticatedData.setRecipientInfos(recipients);
    
    if (digestAlgorithm != null) {
       // create some authenticated attributes
       // (the message digest attribute is automatically added)
       try {
         Attribute[] attributes = { new Attribute(new CMSContentType(contentType)) };
         authenticatedData.setAuthenticatedAttributes(attributes);
       } catch (Exception ex) {
         throw new CMSException("Error creating attribute: " + ex.toString());   
       } 
    }    
    
    // in explicit mode get the content and write it  to any out-of-band place
    if (mode == AuthenticatedDataStream.EXPLICIT) {
      InputStream data_is = authenticatedData.getInputStream();
      byte[] buf = new byte[2048];
      int r;
      while ((r = data_is.read(buf)) > 0) {
        ;   // skip data
      }   
    }    
      
    // return the AuthenticatedData as BER encoded byte array with block size 16
    // (just for testing; in real application we will use a proper blocksize,
    //  e.g. 2048, 4096,..)
    authenticatedData.setBlockSize(16);
    // return the AuthenticatedDate as BER encoded byte array with block size 2048
    ByteArrayOutputStream os = new ByteArrayOutputStream();
    // wrap into ContentInfo
    ContentInfoStream contentInfo = new ContentInfoStream(authenticatedData);
    contentInfo.writeTo(os);
    return os.toByteArray();
  }
  
  /**
   * Creates a CMS <code>AuthenticatedDataOutputStream</code> for the given message message.
   *
   * @param message the message to be authenticated, as byte representation
   * @param macAlgorithm the mac algorithm to be used
   * @param macKeyLength the length of the temporary MAC key to be generated
   * @param digestAlgorithm the digest algorithm to be used to calculate a digest
   *                        from the content if authenticated attributes should
   *                        be included
   * @param mode whether to include the content into the AuthenticatedData ({@link
   *             AuthenticatedDataStream#IMPLICIT implicit}) or to not include it
   *             ({@link AuthenticatedDataStream#EXPLICIT explicit})
   *                                     
   * @return the BER encoding of the <code>AuthenticatedData</code> object just created,
   *         wrapped into a ContentInfo
   * 
   * @throws CMSException if the <code>AuthenticatedData</code> object cannot
   *                          be created
   * @throws IOException if an I/O error occurs
   */
  public byte[] createAuthenticatedDataOutputStream(byte[] message,
                                                    AlgorithmID macAlgorithm,
                                                    int macKeyLength,
                                                    AlgorithmID digestAlgorithm,
                                                    int mode)
    throws CMSException, IOException {
    
    AlgorithmID macAlg = (AlgorithmID)macAlgorithm.clone();
    AlgorithmID digestAlg = null;
    if (digestAlgorithm != null) {
       digestAlg = (AlgorithmID)digestAlgorithm.clone();
    }   
    ObjectID contentType = ObjectID.cms_data;
    
    AuthenticatedDataOutputStream authenticatedData;

    //  a stream from which to read the data to be authenticated
    ByteArrayInputStream is = new ByteArrayInputStream(message);
    
    // the stream to which to write the AuthenticatedData
    ByteArrayOutputStream resultStream = new ByteArrayOutputStream();

    //  wrap AuthenticatedData into a ContentInfo 
    ContentInfoOutputStream contentInfoStream = 
      new ContentInfoOutputStream(ObjectID.cms_authData, resultStream);

    // create AuthenticatedDataOutputStream 
    try {
      authenticatedData = new AuthenticatedDataOutputStream(contentType,
                                                            contentInfoStream, 
                                                            macAlg,
                                                            macKeyLength,
                                                            null,
                                                            digestAlg,
                                                            mode);
    } catch (NoSuchAlgorithmException ex) {
      throw new CMSException(ex.toString());
    }

    // static-static mode: set OriginatorInfo
    OriginatorInfo originator = new OriginatorInfo();
    originator.setCertificates(ecdhOriginatorCerts_);
    authenticatedData.setOriginatorInfo(originator);
    // create the recipient infos
    RecipientInfo[] recipients = createRecipients();
    // specify the recipients of the authenticated message
    authenticatedData.setRecipientInfos(recipients);
    
    if (digestAlgorithm != null) {
       // create some authenticated attributes
       // (the message digest attribute is automatically added)
       try {
         Attribute[] attributes = { new Attribute(new CMSContentType(contentType)) };
         authenticatedData.setAuthenticatedAttributes(attributes);
       } catch (Exception ex) {
         throw new CMSException("Error creating attribute: " + ex.toString());   
       } 
    }    
    
    int blockSize = 20; // in real world we would use a block size like 2048
    //  write in the data to be signed
    byte[] buffer = new byte[blockSize];
    int bytesRead;
    while ((bytesRead = is.read(buffer)) != -1) {
      authenticatedData.write(buffer, 0, bytesRead);
    }
    
    // closing the stream adds auth/unauth attributes, calculates and adds the mac value, . 
    authenticatedData.close();
    return resultStream.toByteArray();
  }
  
  
  /**
   * Decrypts the encrypted MAC key for the recipient identified by its index
   * into the recipientInfos field and uses the MAC key to verify
   * the authenticated data.
   * <p>
   * This way of decrypting the MAC key and verifying the content may be used for 
   * any type of RecipientInfo (KeyTransRecipientInfo, KeyAgreeRecipientInfo, 
   * KEKRecipientInfo, PasswordRecipeintInfo, OtherRecipientInfo), but requires to 
   * know at what index of the recipientInfos field the RecipientInfo for the 
   * particular recipient in mind can be found. 
   * If the recipient in mind uses a RecipientInfo of type KeyAgreeRecipientInfo
   * some processing overhead may take place because a KeyAgreeRecipientInfo may
   * contain encrypted mac keys for more than only one recipient; since the
   * recipientInfoIndex only specifies the RecipientInfo but not the encrypted
   * mac key -- if there are more than only one -- repeated decryption runs may be
   * required as long as the decryption process completes successfully.
   *
   * @param encoding the <code>AuthenticatedData</code> object as BER encoded byte array
   * @param message the content message, if transmitted by other means (explicit mode)
   * @param key the key to decrypt the mac key 
   * @param recipientInfoIndex the index of the right <code>RecipientInfo</code> to 
   *                           which the given key belongs
   *
   * @return the verified message, as byte array
   * 
   * @throws CMSException if the authenticated data cannot be verified
   * @throws IOException if a stream read/write error occurs
   */
  public byte[] getAuthenticatedDataStream(byte[] encoding, 
                                           byte[] message, 
                                           Key key, 
                                           int recipientInfoIndex)
    throws CMSException, IOException {

    // create the AuthenticatedData object from a DER encoded byte array
    // we are testing the stream interface
    ByteArrayInputStream is = new ByteArrayInputStream(encoding);
    AuthenticatedDataStream authenticatedData = new AuthenticatedDataStream(is);
    
    if (authenticatedData.getMode() == AuthenticatedDataStream.EXPLICIT) {
      // in explicit mode explicitly supply the content for hash/mac computation  
      authenticatedData.setInputStream(new ByteArrayInputStream(message));
    }

    System.out.println("\nThis message can be verified by the following recipients:");
    RecipientInfo[] recipients = authenticatedData.getRecipientInfos();
    
    // for demonstration purposes we only look one time for all recipients included:
    if (recipientInfoIndex == 0) {
      int k = 0;
      for (int i=0; i<recipients.length; i++) {
        KeyIdentifier[] recipientIDs = recipients[i].getRecipientIdentifiers();
        for (int j = 0; j < recipientIDs.length; j++) {
          System.out.println("Recipient "+(++k)+":");
          System.out.println(recipientIDs[j]);
        }   
      }
    }
    // decrypt the mac key and verify the mac for the indented recipient
    try {
      authenticatedData.setupMac(key, recipientInfoIndex);
      InputStream contentStream = authenticatedData.getInputStream();
      ByteArrayOutputStream os = new ByteArrayOutputStream();
      Util.copyStream(contentStream, os, null);
      
      if (authenticatedData.verifyMac() == false) {
        throw new CMSException("Mac verification error!");
      }  
      System.out.println("Mac successfully verified!");
      
      return os.toByteArray();

    } catch (InvalidKeyException ex) {
      throw new CMSException("Key error: "+ex.getMessage());
    } catch (NoSuchAlgorithmException ex) {
      throw new CMSException(ex.toString());
    }
  }
  
  /**
   * Decrypts the encrypted MAC key for the recipient identified by recipient identifier
   * and uses the MAC key to verify the authenticated data.
   * <p>
   * This way of decrypting the mac key may be used for any type of RecipientInfo
   * (KeyTransRecipientInfo, KeyAgreeRecipientInfo, KEKRecipientInfo). The 
   * recipient in mind is identified by its recipient identifier.
   *
   * @param encoding the <code>AuthenticatedData</code> object as BER encoded byte array
   * @param message the content message, if transmitted by other means (explicit mode)
   * @param key the key to decrypt the encrypted mac key
   * @param recipientID the recipient identifier uniquely identifying the key of the
   *        recipient
   *
   * @return the verified message, as byte array
   * 
   * @throws CMSException if the authenticated data cannot be verified
   * @throws IOException if a stream read/write error occurs
   */
  public byte[] getAuthenticatedDataStream(byte[] encoding, 
                                           byte[] message,
                                           Key key, 
                                           KeyIdentifier recipientID)
    throws CMSException, IOException {

    // create the AuthenticatedData object from a BER encoded byte array
    // we are testing the stream interface
    ByteArrayInputStream is = new ByteArrayInputStream(encoding);
    AuthenticatedDataStream authenticatedData = new AuthenticatedDataStream(is);
    
    if (authenticatedData.getMode() == AuthenticatedDataStream.EXPLICIT) {
      // in explicit mode explicitly supply the content for hash/mac computation  
      authenticatedData.setInputStream(new ByteArrayInputStream(message));
    }
   
    // get the right RecipientInfo
    System.out.println("\nSearch for RecipientInfo:");
    RecipientInfo recipient = authenticatedData.getRecipientInfo(recipientID);
    if (recipient != null) {
      System.out.println("RecipientInfo: " + recipient);   
    } else {
      throw new CMSException("No recipient with ID: " + recipientID);
    }
    // decrypt the mac key and verify the content mac
    try {
      System.out.println("Decrypt encrypted mac key...");
      SecretKey cek = recipient.decryptKey(key, recipientID);
      System.out.println("Verify content mac with decrypted mac key...");
      authenticatedData.setupMac(cek);
      InputStream contentStream = authenticatedData.getInputStream();
      ByteArrayOutputStream os = new ByteArrayOutputStream();
      Util.copyStream(contentStream, os, null);
      
      if (authenticatedData.verifyMac() == false) {
        throw new CMSException("Mac verification error!");
      } 
      System.out.println("Mac successfully verified!");

      return os.toByteArray();

    } catch (InvalidKeyException ex) {
      throw new CMSException("Key error: "+ex.getMessage());
    } catch (NoSuchAlgorithmException ex) {
      throw new CMSException(ex.toString());
    }
  }
  
  /**
   * Decrypts the encrypted content of the given <code>AuthenticatedData</code> object for
   * the recipient identified by its recipient certificate.
   * <p>
   *
   * @param encoding the <code>AuthenticatedData</code> object as DER encoded byte array
   * @param message the content message, if transmitted by other means (explicit mode) 
   * @param key the key to decrypt the message
   * @param recipientCert the certificate of the recipient having a RecipientInfo of
   *                      type KeyTransRecipientInfo or KeyAgreeRecipientInfo
   *
   * @return the recovered message, as byte array
   * @throws CMSException if the message cannot be recovered
   * @throws IOException if a stream read/write error occurs
   */
  public byte[] getAuthenticatedDataStream(byte[] encoding, 
                                           byte[] message,
                                           Key key, 
                                           X509Certificate recipientCert)
    throws CMSException, IOException {

    // create the AuthenticatedData object from a DER encoded byte array
    // we are testing the stream interface
    ByteArrayInputStream is = new ByteArrayInputStream(encoding);
    AuthenticatedDataStream authenticatedData = new AuthenticatedDataStream(is);
    
    if (authenticatedData.getMode() == AuthenticatedDataStream.EXPLICIT) {
      // in explicit mode explicitly supply the content for hash/mac computation  
      authenticatedData.setInputStream(new ByteArrayInputStream(message));
    }

   
    // decrypt the mac key and verify the content mac
    try {
      System.out.println("Verify mac...");
      authenticatedData.setupMac(key, recipientCert);
      InputStream contentStream = authenticatedData.getInputStream();
      ByteArrayOutputStream os = new ByteArrayOutputStream();
      Util.copyStream(contentStream, os, null);
      
      if (authenticatedData.verifyMac() == false) {
        throw new CMSException("Mac verification error!");
      }
      System.out.println("Mac successfully verified!");

      return os.toByteArray();

    } catch (InvalidKeyException ex) {
      throw new CMSException("Key error: "+ex.getMessage());
    } catch (NoSuchAlgorithmException ex) {
      throw new CMSException(ex.toString());
    }
  }

  
  // non stream

  /**
   * Creates a CMS <code>AuthenticatedData</code> for the given message message.
   *
   * @param message the message to be authenticated, as byte representation
   * @param macAlgorithm the mac algorithm to be used
   * @param macKeyLength the length of the temporary MAC key to be generated
   * @param digestAlgorithm the digest algorithm to be used to calculate a digest
   *                        from the content if authenticated attributes should
   *                        be included
   * @param mode whether to include the content into the AuthenticatedData ({@link
   *             AuthenticatedDataStream#IMPLICIT implicit}) or to not include it
   *             ({@link AuthenticatedDataStream#EXPLICIT explicit}) 
   *                                    
   * @return the BER encoding of the <code>AuthenticatedData</code> object just created
   * 
   * @throws CMSException if the <code>AuthenticatedData</code> object cannot
   *                          be created
   */
  public byte[] createAuthenticatedData(byte[] message,
                                        AlgorithmID macAlgorithm,
                                        int macKeyLength,
                                        AlgorithmID digestAlgorithm,
                                        int mode)
    throws CMSException {
        
    AlgorithmID macAlg = (AlgorithmID)macAlgorithm.clone();
    AlgorithmID digestAlg = null;
    if (digestAlgorithm != null) {
       digestAlg = (AlgorithmID)digestAlgorithm.clone();
    }   
    ObjectID contentType = ObjectID.cms_data;
    
    AuthenticatedData authenticatedData;

    // create a new AuthenticatedData object 
    try {
      authenticatedData = new AuthenticatedData(contentType,
                                                message, 
                                                macAlg,
                                                macKeyLength,
                                                null,
                                                digestAlg,
                                                mode);
    } catch (NoSuchAlgorithmException ex) {
      throw new CMSException(ex.toString());
    }

    // static-static mode: set OriginatorInfo
    OriginatorInfo originator = new OriginatorInfo();
    originator.setCertificates(ecdhOriginatorCerts_);
    authenticatedData.setOriginatorInfo(originator);
    // create the recipient infos
    RecipientInfo[] recipients = createRecipients();
    // specify the recipients of the authenticated message
    authenticatedData.setRecipientInfos(recipients);
    
    if (digestAlgorithm != null) {
       // create some authenticated attributes
       // (the message digest attribute is automatically added)
       try {
         Attribute[] attributes = { new Attribute(new CMSContentType(contentType)) };
         authenticatedData.setAuthenticatedAttributes(attributes);
       } catch (Exception ex) {
         throw new CMSException("Error creating attribute: " + ex.toString());   
       } 
    }    
   
    // wrap into ContentInfo
    ContentInfo contentInfo = new ContentInfo(authenticatedData);
    // return encoded EnvelopedData
    return contentInfo.getEncoded();
  
  }

  /**
   * Decrypts the encrypted MAC key for the recipient identified by its index
   * into the recipientInfos field and uses the MAC key to verify
   * the authenticated data.
   * <p>
   * This way of decrypting the MAC key and verifying the content may be used for 
   * any type of RecipientInfo (KeyTransRecipientInfo, KeyAgreeRecipientInfo, 
   * KEKRecipientInfo), but requires to know at what index of the recipientInfos
   * field the RecipientInfo for the particular recipient in mind can be found. 
   * If the recipient in mind uses a RecipientInfo of type KeyAgreeRecipientInfo
   * some processing overhead may take place because a KeyAgreeRecipientInfo may
   * contain encrypted mac keys for more than only one recipient; since the
   * recipientInfoIndex only specifies the RecipientInfo but not the encrypted
   * mac key -- if there are more than only one -- repeated decryption runs may be
   * required as long as the decryption process completes successfully.
   *
   * @param encoding the <code>AuthenticatedData</code> object as BER encoded byte array
   * @param message the content message, if transmitted by other means (explicit mode)
   * @param key the key to decrypt the mac key
   * @param recipientInfoIndex the index of the right <code>RecipientInfo</code> to 
   *                           which the given key belongs
   *
   * @return the verified message, as byte array
   * @throws CMSException if the authenticated data cannot be verified
   * @throws IOException if a IO read/write error occurs
   */
  public byte[] getAuthenticatedData(byte[] encoding, 
                                     byte[] message,
                                     Key key,
                                     int recipientInfoIndex) 
    throws CMSException, IOException {
        
    // create the AuthenticatedData object from a DER encoded byte array
    ByteArrayInputStream is = new ByteArrayInputStream(encoding);
    AuthenticatedData authenticatedData = new AuthenticatedData(is);
    
    if (authenticatedData.getMode() == AuthenticatedData.EXPLICIT) {
      // in explicit mode explicitly supply the content for hash/mac computation  
      authenticatedData.setContent(message);
    }

    System.out.println("\nThis message can be verified by the owners of the following recipients:");
    RecipientInfo[] recipients = authenticatedData.getRecipientInfos();
    
    // for demonstration purposes we only look one time for all recipients included:
    if (recipientInfoIndex == 0) {
      int k = 0;
      for (int i=0; i<recipients.length; i++) {
        KeyIdentifier[] recipientIDs = recipients[i].getRecipientIdentifiers();
        for (int j = 0; j < recipientIDs.length; j++) {
          System.out.println("Recipient "+(++k)+":");
          System.out.println(recipientIDs[j]);
        }   
      }
    }
    // decrypt the mac key and verify the mac for the first recipient
    try {
      authenticatedData.setupMac(key, recipientInfoIndex);
      if (authenticatedData.verifyMac() == false) {
        throw new CMSException("Mac verification error!");
      }  
      System.out.println("Mac successfully verified!");
      
      return authenticatedData.getContent();

    } catch (InvalidKeyException ex) {
      throw new CMSException("Key error: "+ex.getMessage());
    } catch (NoSuchAlgorithmException ex) {
      throw new CMSException(ex.toString());
    }
  }
  
  /**
   * Decrypts the encrypted content of the given <code>AuthenticatedData</code> object for
   * the recipient identified by recipient identifier.
   * <p>
   * This way of decrypting the content may be used for any type of RecipientInfo
   * (KeyTransRecipientInfo, KeyAgreeRecipientInfo, KEKRecipientInfo). The 
   * recipient in mind is identified by its recipient identifier.
   *
   * @param encoding the DER encoeded <code>AuthenticatedData</code> object#
   * @param message the content message, if transmitted by other means (explicit mode)
   * @param key the key to decrypt the message
   * @param recipientID the recipient identifier uniquely identifying the key of the
   *        recipient
   *
   * @return the recovered message, as byte array
   * @throws CMSException if the message cannot be recovered
   * @throws IOException if an I/O error occurs
   */
  public byte[] getAuthenticatedData(byte[] encoding, 
                                     byte[] message,
                                     Key key, 
                                     KeyIdentifier recipientID) 
    throws CMSException, IOException {
        
    // create the AuthenticatedData object from a DER encoded byte array
    ByteArrayInputStream is = new ByteArrayInputStream(encoding);
    AuthenticatedData authenticatedData = new AuthenticatedData(is);
    
    if (authenticatedData.getMode() == AuthenticatedData.EXPLICIT) {
      // in explicit mode explicitly supply the content for hash/mac computation  
      authenticatedData.setContent(message);
    }
   
    // get the right RecipientInfo
    System.out.println("\nSearch for RecipientInfo:");
    RecipientInfo recipient = authenticatedData.getRecipientInfo(recipientID);
    if (recipient != null) {
      System.out.println("RecipientInfo: " + recipient);   
    } else {
      throw new CMSException("No recipient with ID " + recipientID);
    }
    // decrypt the mac key and verify the content mac
    try {
      System.out.println("Decrypt encrypted mac key...");
      SecretKey cek = recipient.decryptKey(key, recipientID);
      System.out.println("Verify content mac with decrypted mac key...");
      authenticatedData.setupMac(cek);
      
      if (authenticatedData.verifyMac() == false) {
        throw new CMSException("Mac verification error!");
      } 
      System.out.println("Mac successfully verified!");

      return authenticatedData.getContent();

    } catch (InvalidKeyException ex) {
      throw new CMSException("Key error: "+ex.getMessage());
    } 
  }
  
  /**
   * Decrypts the encrypted content of the given <code>AuthenticatedData</code> object for
   * the recipient identified by its recipient certificate.
   * <p>
   *
   * @param encoding the DER encoded <code>AuthenticatedData</code> ASN.1 object
   * @param message the content message, if transmitted by other means (explicit mode) 
   * @param key the key to decrypt the message
   * @param recipientCert the certificate of the recipient having a RecipientInfo of
   *                      type KeyTransRecipientInfo or KeyAgreeRecipientInfo
   *
   * @return the recovered message, as byte array
   * @throws CMSException if the message cannot be recovered
   */
  public byte[] getAuthenticatedData(byte[] encoding, 
                                     byte[] message,
                                     Key key,
                                     X509Certificate recipientCert) 
    throws CMSException, IOException {

    // create the AuthenticatedData object from a DER encoded byte array
    ByteArrayInputStream is = new ByteArrayInputStream(encoding);
    AuthenticatedData authenticatedData = new AuthenticatedData(is);
    
    if (authenticatedData.getMode() == AuthenticatedData.EXPLICIT) {
      // in explicit mode explicitly supply the content for hash/mac computation  
      authenticatedData.setContent(message);
    }

    // decrypt the mac key and verify the content mac
    try {
      System.out.println("Verify mac...");
      authenticatedData.setupMac(key, recipientCert);
      if (authenticatedData.verifyMac() == false) {
        throw new CMSException("Mac verification error!");
      }
      System.out.println("Mac successfully verified!");

      return authenticatedData.getContent();
      
    } catch (InvalidKeyException ex) {
      throw new CMSException("Key error: "+ex.getMessage());
    } catch (NoSuchAlgorithmException ex) {
      throw new CMSException(ex.toString());
    } 
  }
  
  /**
   * Parses an AuthenticatedData and verifies the mac for all recipients
   * using the index into the recipientInfos field for identifying the recipient.
   *
   * @param stream whether to use AuthenticatedDataStream or AuthenticatedData
   * @param encodedAuthenticatedData the encoded AuthenticatedData object 
   * @param message the content message, if transmitted by other means (explicit mode) 
   *
   * @throws Exception if some error occurs during decoding/decryption
   */ 
  public void parseAuthenticatedDataWithRecipientInfoIndex(boolean stream,
    byte[] encodedAuthenticatedData, byte[] message) throws Exception {
    byte[] receivedMessage;
    if (stream) {
      // ecdhUser1
      System.out.println("\nDecrypt for ecdhUser1:");
      receivedMessage = getAuthenticatedDataStream(encodedAuthenticatedData, message, ecdhUser1Pk_, 0);
      System.out.print("\nDecrypted content: ");
      System.out.println(new String(receivedMessage));
      // ecdhUser2
      System.out.println("\nDecrypt for ecdhUser2:");
      receivedMessage = getAuthenticatedDataStream(encodedAuthenticatedData, message, ecdhUser2Pk_, 0);
      System.out.print("\nDecrypted content: ");
      System.out.println(new String(receivedMessage));
    } else {
      // ecdhUser1
      System.out.println("\nDecrypt for ecdhUser1:");
      receivedMessage = getAuthenticatedData(encodedAuthenticatedData, message, ecdhUser1Pk_, 0);
      System.out.print("\nDecrypted content: ");
      System.out.println(new String(receivedMessage));
      // ecdhUser2
      System.out.println("\nDecrypt for ecdhUser2:");
      receivedMessage = getAuthenticatedData(encodedAuthenticatedData, message, ecdhUser2Pk_, 0);
      System.out.print("\nDecrypted content: ");
      System.out.println(new String(receivedMessage));
    }    
  }
  
  /**
   * Parses an AuthenticatedData and verifies the mac for all recipients
   * using their recipient identifiers for identifying the recipient.
   *
   * @param stream whether to use AuthenticatedDataStream or AuthenticatedData
   * @param encodedAuthenticatedData the encoded AuthenticatedData object 
   * @param message the content message, if transmitted by other means (explicit mode)
   *
   * @throws Exception if some error occurs during decoding/decryption
   */ 
  public void parseAuthenticatedDataWithRecipientIdentifier(boolean stream, byte[] encodedAuthenticatedData,
    byte[] message) throws Exception {
    byte[] receivedMessage;
    if (stream) {
      // ecdhUser1
      System.out.println("\nDecrypt for ecdhUser1:");
      receivedMessage = getAuthenticatedDataStream(encodedAuthenticatedData, message, ecdhUser1Pk_, new IssuerAndSerialNumber(ecdhUser1_));
      System.out.print("\nDecrypted content: ");
      System.out.println(new String(receivedMessage));
      // ecdhUser2
      System.out.println("\nDecrypt for ecdhUser2:");
      receivedMessage = getAuthenticatedDataStream(encodedAuthenticatedData, message, ecdhUser2Pk_, new RecipientKeyIdentifier(ecdhUser2_));
      System.out.print("\nDecrypted content: ");
      System.out.println(new String(receivedMessage));
    } else {
      // ecdhUser1
      System.out.println("\nDecrypt for ecdhUser1:");
      receivedMessage = getAuthenticatedData(encodedAuthenticatedData, message, ecdhUser1Pk_, new IssuerAndSerialNumber(ecdhUser1_));
      System.out.print("\nDecrypted content: ");
      System.out.println(new String(receivedMessage));
      // ecdhUser2
      System.out.println("\nDecrypt for ecdhUser2:");
      receivedMessage = getAuthenticatedData(encodedAuthenticatedData, message, ecdhUser2Pk_, new RecipientKeyIdentifier(ecdhUser2_));
      System.out.print("\nDecrypted content: ");
      System.out.println(new String(receivedMessage));
    }    
  }
  
  /**
   * Parses an AuthenticatedData and verifies the mac for all recipients
   * using the recipient certificate for identifying the recipient.
   *
   * @param stream whether to use AuthenticatedDataStream or AuthenticatedData
   * @param encodedAuthenticatedData the encoded AuthenticatedData object 
   * @param message the content message, if transmitted by other means (explicit mode)
   *
   * @throws Exception if some error occurs during decoding/decryption
   */ 
  public void parseAuthenticatedDataWithRecipientCertificate(boolean stream, byte[] encodedAuthenticatedData,
    byte[] message) throws Exception {
    byte[] receivedMessage;
    if (stream) {
      // ecdhUser1
      System.out.println("\nDecrypt for ecdhUser1:");
      receivedMessage = getAuthenticatedDataStream(encodedAuthenticatedData, message, ecdhUser1Pk_, ecdhUser1_);
      System.out.print("\nDecrypted content: ");
      System.out.println(new String(receivedMessage));
      // ecdhUser2
      System.out.println("\nDecrypt for ecdhUser2:");
      receivedMessage = getAuthenticatedDataStream(encodedAuthenticatedData, message, ecdhUser2Pk_, ecdhUser2_);
      System.out.print("\nDecrypted content: ");
      System.out.println(new String(receivedMessage));
    } else {
      // ecdhUser1
      System.out.println("\nDecrypt for ecdhUser1:");
      receivedMessage = getAuthenticatedData(encodedAuthenticatedData, message, ecdhUser1Pk_, ecdhUser1_);
      System.out.print("\nDecrypted content: ");
      System.out.println(new String(receivedMessage));
      // ecdhUser2
      System.out.println("\nDecrypt for ecdhUser2:");
      receivedMessage = getAuthenticatedData(encodedAuthenticatedData, message, ecdhUser2Pk_, ecdhUser2_);
      System.out.print("\nDecrypted content: ");
      System.out.println(new String(receivedMessage));
    }    
  }
  
  
  
  /**
   * Starts the demo.
   */
  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();
    
    AlgorithmID macAlgorithm = (AlgorithmID)AlgorithmID.hMAC_SHA256.clone();
    int macKeyLength = 32;
    AlgorithmID digestAlgorithm = (AlgorithmID)AlgorithmID.sha256.clone();

    try {
      byte[] encoding;
      System.out.println("Stream implementation demos");
      System.out.println("===========================");


      // the stream implementation
      //
      // test CMS AuthenticatedDataStream
      //

      int[] modes = { AuthenticatedDataStream.IMPLICIT, AuthenticatedDataStream.EXPLICIT };
      
      for (int i = 0; i < modes.length; i++) {
        int mode = modes[i];
        if (mode == AuthenticatedDataStream.IMPLICIT) {
          System.out.print("Implicit ");
        } else {
          System.out.print("Explicit ");
        }
        // with authenticated attributes
        System.out.println("AuthenticatedDataStream demo with authenticated attributes [create]:\n");
        encoding =  createAuthenticatedDataStream(message,
                                                  macAlgorithm,
                                                  macKeyLength,
                                                  digestAlgorithm,
                                                  mode);
        // transmit data
        System.out.println("\nAuthenticatedDataStream demo with authenticated attributes [parse]:\n");
        System.out.println("Parse for the several recipients using their index into the recipientInfos field.");
        parseAuthenticatedDataWithRecipientInfoIndex(true, encoding, message);
        System.out.println("Parse for the several recipients using their RecipientIdentifier.");
        parseAuthenticatedDataWithRecipientIdentifier(true, encoding, message);
        System.out.println("Parse for the several recipients using their certificate.");
        parseAuthenticatedDataWithRecipientCertificate(true, encoding, message);
        
        // without authenticated attributes
        System.out.println("AuthenticatedDataStream demo without authenticated attributes [create]:\n");
        encoding =  createAuthenticatedDataStream(message,
                                                  macAlgorithm,
                                                  macKeyLength,
                                                  null,
                                                  mode);
        // transmit data
        System.out.println("\nAuthenticatedDataStream demo without authenticated attributes [parse]:\n");
        System.out.println("Parse for the several recipients using their index into the recipientInfos field.");
        parseAuthenticatedDataWithRecipientInfoIndex(true, encoding, message);
        System.out.println("Parse for the several recipients using their RecipientIdentifier.");
        parseAuthenticatedDataWithRecipientIdentifier(true, encoding, message);
        System.out.println("Parse for the several recipients using their certificate.");
        parseAuthenticatedDataWithRecipientCertificate(true, encoding, message);
     
      }
      
      System.out.println("\nOutputStream implementation demos");
      System.out.println("=================================");


      // the output stream implementation
      //
      // test CMS AuthenticatedDataOutputStream
      //
      for (int i = 0; i < modes.length; i++) {
        int mode = modes[i];
        if (mode == AuthenticatedDataStream.IMPLICIT) {
          System.out.print("Implicit ");
        } else {
          System.out.print("Explicit ");
        }
        // with authenticated attributes
        System.out.println("AuthenticatedDataOutputStream demo with authenticated attributes [create]:\n");
        encoding =  createAuthenticatedDataOutputStream(message,
                                                        macAlgorithm,
                                                        macKeyLength,
                                                        digestAlgorithm,
                                                        mode);
        // transmit data
        System.out.println("\nAuthenticatedDataStream demo with authenticated attributes [parse]:\n");
        System.out.println("Parse for the several recipients using their index into the recipientInfos field.");
        parseAuthenticatedDataWithRecipientInfoIndex(true, encoding, message);
        System.out.println("Parse for the several recipients using their RecipientIdentifier.");
        parseAuthenticatedDataWithRecipientIdentifier(true, encoding, message);
        System.out.println("Parse for the several recipients using their certificate.");
        parseAuthenticatedDataWithRecipientCertificate(true, encoding, message);
        
        // without authenticated attributes
        System.out.println("AuthenticatedDataOutputStream demo without authenticated attributes [create]:\n");
        encoding =  createAuthenticatedDataOutputStream(message,
                                                  macAlgorithm,
                                                  macKeyLength,
                                                  null,
                                                  mode);
        // transmit data
        System.out.println("\nAuthenticatedDataOutputStream demo without authenticated attributes [parse]:\n");
        System.out.println("Parse for the several recipients using their index into the recipientInfos field.");
        parseAuthenticatedDataWithRecipientInfoIndex(true, encoding, message);
        System.out.println("Parse for the several recipients using their RecipientIdentifier.");
        parseAuthenticatedDataWithRecipientIdentifier(true, encoding, message);
        System.out.println("Parse for the several recipients using their certificate.");
        parseAuthenticatedDataWithRecipientCertificate(true, encoding, message);
     
      }
      System.out.println("===============================");

            
      //
      // test CMS AuthenticatedData
      //
      for (int i = 0; i < modes.length; i++) {
        int mode = modes[i];
        if (mode == AuthenticatedDataStream.IMPLICIT) {
          System.out.print("Implicit ");
        } else {
          System.out.print("Explicit ");
        }
        // with authenticated attributes
        System.out.println("AuthenticatedData demo with authenticated attributes [create]:\n");
        encoding =  createAuthenticatedData(message,
                                           macAlgorithm,
                                           macKeyLength,
                                           digestAlgorithm,
                                           mode);
        // transmit data
        System.out.println("\nAuthenticatedDataStream demo with authenticated attributes [parse]:\n");
        System.out.println("Parse for the several recipients using their index into the recipientInfos field.");
        parseAuthenticatedDataWithRecipientInfoIndex(false, encoding, message);
        System.out.println("Parse for the several recipients using their RecipientIdentifier.");
        parseAuthenticatedDataWithRecipientIdentifier(false, encoding, message);
        System.out.println("Parse for the several recipients using their certificate.");
        parseAuthenticatedDataWithRecipientCertificate(false, encoding, message);
        
        // without authenticated attributes
        System.out.println("AuthenticatedData demo without authenticated attributes [create]:\n");
        encoding =  createAuthenticatedData(message,
                                            macAlgorithm,
                                            macKeyLength,
                                            null,
                                            mode);
        // transmit data
        System.out.println("\nAuthenticatedData demo without authenticated attributes [parse]:\n");
        System.out.println("Parse for the several recipients using their index into the recipientInfos field.");
        parseAuthenticatedDataWithRecipientInfoIndex(false, encoding, message);
        System.out.println("Parse for the several recipients using their RecipientIdentifier.");
        parseAuthenticatedDataWithRecipientIdentifier(false, encoding, message);
        System.out.println("Parse for the several recipients using their certificate.");
        parseAuthenticatedDataWithRecipientCertificate(false, encoding, message);
     
      }
      
      

    } catch (Exception ex) {
      ex.printStackTrace();
      throw new RuntimeException(ex.toString());
    }
  }
  
  /**
   * Main method.
   *
   * @throws IOException
   *            if an I/O error occurs when reading required keys
   *            and certificates from the keystore file
   */
  public static void main(String argv[]) throws Exception {

    DemoUtil.initDemos();
    ECCDemoUtil.installIaikEccProvider();
    (new ECDHAuthenticatedDataDemo()).start();
    System.out.println("\nReady!");
    System.in.read();
  }
}