import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.lang.System;
import java.security.cert.Certificate;
import java.security.Key;
import java.security.KeyStore;
import java.security.PrivateKey;
import java.security.Security;

import com.itextpdf.text.Rectangle;
import com.itextpdf.text.pdf.PdfReader;
import com.itextpdf.text.pdf.PdfStamper;
import com.itextpdf.text.pdf.PdfSignatureAppearance;
import com.itextpdf.text.pdf.security.BouncyCastleDigest;
import com.itextpdf.text.pdf.security.ExternalDigest;
import com.itextpdf.text.pdf.security.ExternalSignature;
import com.itextpdf.text.pdf.security.MakeSignature;
import com.itextpdf.text.pdf.security.MakeSignature.CryptoStandard;
import com.itextpdf.text.pdf.security.PrivateKeySignature;

import org.bouncycastle.jce.provider.BouncyCastleProvider;

public class sign {

public static void main(String[] args)
{
  PdfReader reader;
  PdfSignatureAppearance sap;
  PdfStamper stp;
  FileOutputStream fout;
  PrivateKey key;
  PrivateKeySignature es;
  ExternalDigest digest;
  String hashName;

  Certificate[] chain;
  KeyStore ks;

  try {
    Security.addProvider(new BouncyCastleProvider());
  } catch(Exception e) {
    System.out.print("Error adding security provider BouncyCastle: " + e + "\n");
    System.exit(1); return;
  }

  try {
    ks = KeyStore.getInstance("PKCS12", "BC");
    ks.load(new FileInputStream(args[0]), args[1].toCharArray());
  } catch(Exception e) {
    System.out.print("Error loading certificate store: " + e + "\n");
    System.exit(1); return;
  }

  try {
    String alias = (String)ks.aliases().nextElement();
    key = (PrivateKey)ks.getKey(alias, args[1].toCharArray());
    chain = ks.getCertificateChain(alias);
  } catch(Exception e) {
    System.out.print("Problems loading key or chain: " + e + "\n");
    System.exit(1); return;
  }

  if (key == null) {
    System.out.print("Failed to get key from the keystore: no keys found\n");
    System.exit(1); return;
  }

  //System.out.print("key uses algorithm " + key.getAlgorithm() + "\n");

  if (chain == null) {
    System.out.print("Failed to get certificate chain from the keystore: no certificates found\n");
    System.exit(1); return;
  }

  try {
    reader = new PdfReader(args[3]);
  } catch(Exception e) {
    System.out.print("Problems initializing PDF reader: " + e + "\n");
    System.exit(1); return;
  }

  try {
    fout = new FileOutputStream(args[4]);
  } catch(Exception e) {
    System.out.print("Failed to create file " + args[4] + ": " + e + "\n");
    System.exit(1); return;
  }

  try {
//  stp = PdfStamper.createSignature(reader, fout, '\0', new File("/tmp"));
    stp = PdfStamper.createSignature(reader, fout, '\0'); // in-memory processing
    sap = stp.getSignatureAppearance();
  } catch(Exception e) {
    System.out.print("Problems creating signature: " + e + "\n");
    System.exit(1); return;
  }

  try {
    es = new PrivateKeySignature(key, args[2], "BC");
    // workaround itextpdf-5.5.9 bug
    es.setEncryptionAlgorithm(key.getAlgorithm());
  }
  catch(Exception e)
  {
    System.out.print("Problems creating PrivateKeySignature: " + e + "\n");
    System.exit(1); return;
  }
  if (es == null) {
    System.out.print("Problems creating PrivateKeySignature: null\n");
    System.exit(1); return;
  }

  if (es.getHashAlgorithm() == null) {
    System.out.print("No usable hash algorithm found\n");
    System.exit(1); return;
  }

  try {
    digest = new BouncyCastleDigest();
  } catch(Exception e) {
    System.out.print("Problems creating BouncyCastleDigest: " + e + "\n");
    System.exit(1); return;
  }

  try {
    sap.setReason(args[5]);
    sap.setLocation(args[6]);
    sap.setContact(args[7]);
    sap.setCertificationLevel(PdfSignatureAppearance.CERTIFIED_NO_CHANGES_ALLOWED);
  } catch(Exception e) {
    System.out.print("Problem setting settings: " + e + "\n");
    System.exit(1); return;
  }

  try {
    MakeSignature.signDetached(sap, digest, es, chain, null, null, null, 0, CryptoStandard.CMS);
  } catch(Exception e) {
    System.out.print("Problem signing: " + e + "\n");
    System.exit(1); return;
  }

  try {
    stp.close();
  } catch(Exception e) {
    System.out.print("Problem closing: " + e + "\n");
    System.exit(1); return;
  }
  System.out.print("Done.\n");
}

}