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Una librería para firma digital

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/*
 * Copyright 2009-2018 Rubrica
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program.  If not, see .
 */

package io.rubrica.sign.pdf;

import java.awt.Color;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.lang.reflect.Field;
import java.security.PrivateKey;
import java.security.cert.Certificate;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.List;
import java.util.Properties;
import java.util.logging.Logger;

import com.lowagie.text.DocumentException;
import com.lowagie.text.Font;
import com.lowagie.text.Paragraph;
import com.lowagie.text.Rectangle;
import com.lowagie.text.pdf.AcroFields;
import com.lowagie.text.pdf.ColumnText;
import com.lowagie.text.pdf.PdfDictionary;
import com.lowagie.text.pdf.PdfName;
import com.lowagie.text.pdf.PdfPKCS7;
import com.lowagie.text.pdf.PdfReader;
import com.lowagie.text.pdf.PdfSignatureAppearance;
import com.lowagie.text.pdf.PdfStamper;
import com.lowagie.text.pdf.PdfTemplate;

import io.rubrica.core.RubricaException;
import io.rubrica.sign.InvalidFormatException;
import io.rubrica.sign.SignInfo;
import io.rubrica.sign.Signer;
import io.rubrica.util.BouncyCastleUtils;
import io.rubrica.util.Utils;

public class PDFSigner implements Signer {

	private static final String PDF_FILE_HEADER = "%PDF-";
	private static final PdfName PDFNAME_ETSI_RFC3161 = new PdfName("ETSI.RFC3161");
	private static final PdfName PDFNAME_DOCTIMESTAMP = new PdfName("DocTimeStamp");

	/** Referencia a la última página del documento PDF. */
	private static final Logger logger = Logger.getLogger(PDFSigner.class.getName());

	/**
	 * Razón por la que se realiza la firma.
	 */
	public static final String SIGNING_REASON = "signingReason";

	/**
	 * Localización en la que se realiza la firma.
	 */
	public static final String SIGNING_LOCATION = "signingLocation";
	public static final String SIGN_TIME = "signTime";
	public static final String SIGNATURE_PAGE = "signingPage";
	public static final String LAST_PAGE = "0";
	public static final String FONT_SIZE = "3";
	public static final String TYPE_SIG = "information1";
	public static final String INFO_QR = "";

	static {
		BouncyCastleUtils.initializeBouncyCastle();
	}

	// ETSI TS 102 778-1 V1.1.1 (2009-07)
	// PAdES Basic - Profile based on ISO 32000-1
	/**
	 * Algoritmos soportados:
	 *
	 * 
  • SHA1withRSA
    • 
	 * 
  • SHA256withRSA
    • 
	 * 
  • SHA384withRSA
    • 
	 * 
  • SHA512withRSA
    • 
	 */
	@Override
	public byte[] sign(byte[] data, String algorithm, PrivateKey key, Certificate[] certChain, Properties xParams)
			throws RubricaException, IOException {

		Properties extraParams = xParams != null ? xParams : new Properties();

		// Motivo de la firma
		String reason = extraParams.getProperty(SIGNING_REASON);

		// Lugar de realizacion de la firma
		String location = extraParams.getProperty(SIGNING_LOCATION);

		// Fecha y hora de la firma, en formato ISO-8601
		String signTime = extraParams.getProperty(SIGN_TIME);

		// Tamaño letra
		float fontSize = 3;
		try {
			if (extraParams.getProperty(FONT_SIZE) == null)
				fontSize = 3;
			else
				fontSize = Float.parseFloat(extraParams.getProperty(FONT_SIZE).trim());
		} catch (final Exception e) {
			logger.warning("Se ha indicado un tamaño de letra invalida ('" + extraParams.getProperty(FONT_SIZE)
					+ "'), se usara el tamaño por defecto: " + fontSize + " " + e);
		}

		// Tipo de firma (Información, QR)
		String typeSig = extraParams.getProperty(TYPE_SIG);
		if (typeSig == null)
			typeSig = "information1";

		if (typeSig.equals("QR") && extraParams.getProperty(FONT_SIZE) == null)
			fontSize = 4.5f;

		// Información QR
		String infoQR = "";
		if (extraParams.getProperty(INFO_QR) == null)
			infoQR = "";
		else
			infoQR = extraParams.getProperty(INFO_QR).trim();

		// Tamaño espaciado
		float fontLeading = fontSize;

		// Pagina donde situar la firma visible
		int page = 0;
		try {
			if (extraParams.getProperty(LAST_PAGE) == null)
				page = 0;
			else
				page = Integer.parseInt(extraParams.getProperty(LAST_PAGE).trim());
		} catch (final Exception e) {
			logger.warning("Se ha indicado un numero de pagina invalido ('" + extraParams.getProperty(LAST_PAGE)
					+ "'), se usara la ultima pagina: " + e);
		}

		// Leer el PDF
		PdfReader pdfReader = new PdfReader(data);
		ByteArrayOutputStream baos = new ByteArrayOutputStream();

		PdfStamper stp;

		try {
			stp = PdfStamper.createSignature(pdfReader, baos, '\0', null, true);
		} catch (DocumentException e) {
			logger.severe("Error al crear la firma para estampar: " + e);
			throw new RubricaException("Error al crear la firma para estampar", e);
		}

		PdfSignatureAppearance sap = stp.getSignatureAppearance();
		sap.setAcro6Layers(true);

		// Razon de firma
		if (reason != null) {
			sap.setReason(reason);
		}

		// Localizacion en donde se produce la firma
		if (location != null) {
			sap.setLocation(location);
		}

		// Fecha y hora de la firma
		if (signTime != null) {
			Date date = Utils.getSignTime(signTime);
			GregorianCalendar calendar = new GregorianCalendar();
			calendar.setTime(date);
			sap.setSignDate(calendar);
		}

		if (page == 0 || page < 0 || page > pdfReader.getNumberOfPages())
			page = pdfReader.getNumberOfPages();

		Rectangle signaturePositionOnPage = getSignaturePositionOnPage(extraParams);

		if (signaturePositionOnPage != null) {
			sap.setVisibleSignature(signaturePositionOnPage, page, null);

			X509Certificate x509Certificate = (X509Certificate) certChain[0];
			String informacionCertificado = x509Certificate.getSubjectDN().getName();
			String nombreFirmante = (informacionCertificado.substring(informacionCertificado.lastIndexOf("CN=") + 3,
					informacionCertificado.indexOf(","))).toUpperCase();
			try {
				// Creating the appearance for layer 0
				PdfTemplate pdfTemplate = sap.getLayer(0);
				float width = pdfTemplate.getBoundingBox().getWidth();
				float height = pdfTemplate.getBoundingBox().getHeight();
				pdfTemplate.rectangle(0, 0, width, height);
				// Color de fondo
				// pdfTemplate.setColorFill(Color.LIGHT_GRAY);
				// pdfTemplate.fill();
				// Color de fondo
				switch (typeSig) {
				case "QR": {
					// Creating the appearance for layer 2
					// Nombre Firmante
					// nombreFirmante = nombreFirmante+" "+nombreFirmante;
					// nombreFirmante="PRUEBA QUIPUX MISAEL FERNANDEZ";
					// nombreFirmante="JOSE DAVID GAMBOA VERA";
					PdfTemplate pdfTemplate1 = sap.getLayer(2);
					Font font = new Font(Font.COURIER, fontSize + (fontSize / 2), Font.BOLD, Color.BLACK);
					float maxFontSize = getMaxFontSize(com.lowagie.text.pdf.BaseFont.createFont(),
							nombreFirmante.trim(), width - ((width / 3) + 3));
					font.setSize(maxFontSize);
					fontLeading = maxFontSize;

					Paragraph paragraph = new Paragraph("Firmado electrónicamente por:\n",
							new Font(Font.COURIER, fontSize / 1.25f, Font.NORMAL, Color.BLACK));
					paragraph.add(new Paragraph(nombreFirmante.trim(), font));
					paragraph.setAlignment(Paragraph.ALIGN_LEFT);
					paragraph.setLeading(fontLeading);
					ColumnText columnText = new ColumnText(pdfTemplate1);
					columnText.setSimpleColumn((width / 3) + 3, 0, width, height);
					columnText.addElement(paragraph);
					columnText.go();
					// Imagen
					java.awt.image.BufferedImage bufferedImage = null;
					// QR
					String text = "FIRMADO POR: " + nombreFirmante.trim() + "\n";
					text = text + "RAZON: " + reason + "\n";
					text = text + "FECHA: " + signTime + "\n";
					text = text + infoQR;
					try {
						bufferedImage = io.rubrica.util.QRCode.generateQR(text, (int) height, (int) height);
					} catch (Exception e) {
						e.printStackTrace();
					}
					// QR
					PdfTemplate pdfTemplateImage = sap.getLayer(2);
					ColumnText columnTextImage = new ColumnText(pdfTemplateImage);
					columnTextImage.setSimpleColumn(0, 0, width / 3, height);
					columnTextImage.setAlignment(Paragraph.ALIGN_CENTER);
					columnTextImage.addElement(com.lowagie.text.Image.getInstance(bufferedImage, null));
					columnTextImage.go();
					break;
				}
				case "information1": {
					// Creating the appearance for layer 2
					// Nombre Firmante
					PdfTemplate pdfTemplate1 = sap.getLayer(2);
					Font font1 = new Font(Font.ITALIC, fontSize + (fontSize / 2), Font.BOLD, Color.BLACK);
					// Font font1 = new Font(Font.ITALIC, 5.0f, Font.BOLD, Color.BLACK);
					Paragraph paragraph1 = new Paragraph(nombreFirmante.trim(), font1);
					paragraph1.setAlignment(Paragraph.ALIGN_RIGHT);
					ColumnText columnText1 = new ColumnText(pdfTemplate1);
					columnText1.setSimpleColumn(0, 0, (width / 2) - 1, height);
					columnText1.addElement(paragraph1);
					columnText1.go();
					// Segunda Columna
					PdfTemplate pdfTemplate2 = sap.getLayer(2);
					Font font2 = new Font(Font.ITALIC, fontSize, Font.NORMAL, Color.DARK_GRAY);
					Paragraph paragraph2 = new Paragraph(fontLeading, "Nombre de reconocimiento "
							+ informacionCertificado.trim() + "\nRazón: " + reason + "\nFecha: " + signTime, font2);
					paragraph2.setAlignment(Paragraph.ALIGN_LEFT);
					ColumnText columnText2 = new ColumnText(pdfTemplate2);
					columnText2.setSimpleColumn((width / 2) + 1, 0, width, height);
					columnText2.addElement(paragraph2);
					columnText2.go();
					break;
				}
				case "information2": {
					// Creating the appearance for layer 2
					// ETSI TS 102 778-6 V1.1.1 (2010-07)
					Font font = new Font(Font.HELVETICA, fontSize, Font.BOLD, Color.BLACK);
					com.lowagie.text.pdf.BaseFont baseFont = com.lowagie.text.pdf.BaseFont.createFont();

					float x = Float.parseFloat(extraParams.getProperty("PositionOnPageLowerLeftX").trim());
					float y = Float.parseFloat(extraParams.getProperty("PositionOnPageLowerLeftY").trim());
					nombreFirmante = nombreFirmante.replace(" ", "*");
					width = baseFont.getWidthPoint(nombreFirmante, font.getSize());
					nombreFirmante = nombreFirmante.replace("*", " ");
					height = font.getSize() * 3;
					sap.setVisibleSignature(new Rectangle(x, y, x + width, y - height), page, null);
					pdfTemplate = sap.getLayer(0);
					pdfTemplate.rectangle(0, 0, width, height);
					PdfTemplate pdfTemplate1 = sap.getLayer(2);

					Paragraph paragraph = new Paragraph(fontLeading, "Firmado digitalmente por:\n",
							new Font(Font.HELVETICA, fontSize / 1.5f, Font.NORMAL, Color.BLACK));
					paragraph.add(new Paragraph(fontLeading, nombreFirmante, font));
					paragraph.add(new Paragraph(fontLeading, "Fecha: " + signTime,
							new Font(Font.HELVETICA, fontSize / 1.5f, Font.NORMAL, Color.BLACK)));
					paragraph.setAlignment(Paragraph.ALIGN_LEFT);
					ColumnText columnText = new ColumnText(pdfTemplate1);
					columnText.setSimpleColumn(0, 0, width, height);
					columnText.addElement(paragraph);
					columnText.go();
					break;
				}
				default: {
				}
				}
			} catch (DocumentException e) {
				logger.severe("Error al estampar la firma: " + e);
				throw new RubricaException("Error al estampar la firma", e);
			}
		}

		sap.setCrypto(key, (X509Certificate) certChain[0], null, PdfSignatureAppearance.WINCER_SIGNED);

		try {
			stp.close();
		} catch (DocumentException e) {
			logger.severe("Error al estampar la firma: " + e);
			throw new RubricaException("Error al estampar la firma", e);
		}

		return baos.toByteArray();
	}

	private float getMaxFontSize(com.lowagie.text.pdf.BaseFont baseFont, String text, float width) {
		float measureWidth = 1;
		float fontSize = 0.1f;
		float oldSize = 0.1f;
		int repeat = 0;
		float multiply = 1;
		text = text.replace(" ", "*");
		while (measureWidth < width) {
			repeat++;
			measureWidth = baseFont.getWidthPoint(text, fontSize);
			oldSize = fontSize;
			fontSize += 0.1f;
		}
		System.out.println("repeat: " + repeat);
		System.out.println("fontSize: " + fontSize);
		if (repeat > 60)
			multiply = 1;
		if (repeat <= 60 && repeat > 20)
			multiply = 2;
		if (repeat <= 20 && repeat > 10)
			multiply = 3;
		if (repeat <= 10)
			multiply = 4;

		if (fontSize > 20) {
			oldSize = 20;
			multiply = 1;
		}
		return oldSize * multiply;
	}

	@Override
	public List getSigners(byte[] sign) throws InvalidFormatException, IOException {
		if (!isPdfFile(sign)) {
			throw new InvalidFormatException("El archivo no es un PDF");
		}

		PdfReader pdfReader;

		try {
			pdfReader = new PdfReader(sign);
		} catch (Exception e) {
			logger.severe("No se ha podido leer el PDF: " + e);
			throw new InvalidFormatException("No se ha podido leer el PDF", e);
		}

		AcroFields af;

		try {
			af = pdfReader.getAcroFields();
		} catch (Exception e) {
			logger.severe(
					"No se ha podido obtener la informacion de los firmantes del PDF, se devolvera un arbol vacio: "
							+ e);
			throw new InvalidFormatException("No se ha podido obtener la informacion de los firmantes del PDF", e);
		}

		@SuppressWarnings("unchecked")
		List names = af.getSignatureNames();

		Object pkcs1Object = null;
		List signInfos = new ArrayList<>();

		for (String signatureName : names) {
			// Comprobamos si es una firma o un sello
			PdfDictionary pdfDictionary = af.getSignatureDictionary(signatureName);

			if (PDFNAME_ETSI_RFC3161.equals(pdfDictionary.get(PdfName.SUBFILTER))
					|| PDFNAME_DOCTIMESTAMP.equals(pdfDictionary.get(PdfName.SUBFILTER))) {
				// Ignoramos los sellos
				continue;
			}

			PdfPKCS7 pcks7;

			try {
				pcks7 = af.verifySignature(signatureName);
			} catch (Exception e) {
				e.printStackTrace();
				logger.severe("El PDF contiene una firma corrupta o con un formato desconocido (" + signatureName
						+ "), se continua con las siguientes si las hubiese: " + e);
				continue;
			}

			Certificate[] signCertificateChain = pcks7.getSignCertificateChain();
			X509Certificate[] certChain = new X509Certificate[signCertificateChain.length];

			for (int i = 0; i < certChain.length; i++) {
				certChain[i] = (X509Certificate) signCertificateChain[i];
			}

			SignInfo signInfo = new SignInfo(certChain, pcks7.getSignDate().getTime());

			// Extraemos el PKCS1 de la firma
			try {
				// iText antiguo
				Field digestField = Class.forName("com.lowagie.text.pdf.PdfPKCS7").getDeclaredField("digest");
				digestField.setAccessible(true);
				pkcs1Object = digestField.get(pcks7);

				if (pkcs1Object instanceof byte[]) {
					signInfo.setPkcs1((byte[]) pkcs1Object);
				}
			} catch (Exception e) {
				e.printStackTrace();
				logger.severe(
						"No se ha podido obtener informacion de una de las firmas del PDF, se continuara con la siguiente: "
								+ e);
				continue;
			}

			signInfos.add(signInfo);
		}

		return signInfos;
	}

	private boolean isPdfFile(final byte[] data) {

		byte[] buffer = new byte[PDF_FILE_HEADER.length()];

		try {
			new ByteArrayInputStream(data).read(buffer);
		} catch (Exception e) {
			buffer = null;
		}

		// Comprobamos que cuente con una cabecera PDF
		if (buffer != null && !PDF_FILE_HEADER.equals(new String(buffer))) {
			return false;
		}

		try {
			// Si lanza una excepcion al crear la instancia, no es un fichero
			// PDF
			new PdfReader(data);
		} catch (final Exception e) {
			return false;
		}

		return true;
	}

	private static Rectangle getSignaturePositionOnPage(Properties extraParams) {
		return PdfUtil.getPositionOnPage(extraParams);
	}
}




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