package com.zhou.stamp;
import com.itextpdf.text.Image;
import com.itextpdf.text.Rectangle;
import com.itextpdf.text.pdf.PdfReader;
import com.itextpdf.text.pdf.PdfSignatureAppearance;
import com.itextpdf.text.pdf.PdfStamper;
import com.itextpdf.text.pdf.security.*;
import lombok.Data;
import lombok. SneakyThrows;
import org.springframework.beans.BeanUtils;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.KeyStore;
import java.security.PrivateKey;
import java.security.cert.Certificate;
import java.util.Calendar;
/**
* @author lang.zhou
* @since 2023/8/1 13:42
*/
@Data
public class PDFStamper {
private String pdf;
public static void main(String[] args) throws Exception{
PDFStamper stamper = new PDFStamper();
stamper.setPdf("C:\Users\zhou\Desktop\2.pdf");
StampOption option = new StampOption();
PdfSignDto signDto = new PdfSignDto();
signDto.setContact("zhoulang");
signDto.setLocation("cn");
signDto.setSignDate(Calendar.getInstance());
signDto.setReason("Stamp");
option.setSignDto(signDto);
//stamp image
option.setImgPath("C:\Users\zhou\Desktop\stamp2.jpeg");
//stamp coordinates (center point)
option.setX(200);
option.setY(200);
//Chapter width and height, empty default image actual size
option. setWidth(100);
option. setHeight(100);
option.setPage(1);
stamper.stamp(new FileInputStream("C:\Users\zhou\Desktop\1.pfx"),"certificate password",option, new FileOutputStream(\ "C:\Users\zhou\Desktop\3.pdf"));
}
/**
* Calculate the diagonal coordinates of the signature (upper left, lower right)
*/
private float[] calcImagePosition(Image image, StampOption stampOption){
float[] pos = new float[4];
float w = stampOption. getWidth();
float h = stampOption. getHeight();
if(w == 0 || h == 0){
w = image. getWidth();
h = image. getHeight();
}
pos[0] = stampOption.getX() - w / 2;
pos[1] = stampOption.getY() - h / 2;
pos[2] = stampOption.getX() + w / 2;
pos[3] = stampOption. getY() + h / 2;
return pos;
}
/**
* Signed and sealed
* @param p12 pkcs12/pfx format certificate file stream
* @param password certificate password
* @param stampOption stamp option
* @param out Output file stream after stamping
*/
@SneakyThrows
public void stamp(InputStream p12, String password, StampOption stampOption, OutputStream out){
//Read keystore, get private key and certificate chain
KeyStore ks = KeyStore. getInstance("PKCS12");
char[] chars = password. toCharArray();
ks.load(p12, chars);
String alias = ks. aliases(). nextElement();
PrivateKey pk = (PrivateKey) ks.getKey(alias, chars);
Certificate[] chain = ks. getCertificateChain(alias);
PdfReader pdfReader = new PdfReader(pdf);
// target file output stream
//Create the signature tool PdfStamper, the last boolean parameter
//If false, the pdf file is only allowed to be signed once, multiple signatures, the last one is valid
//If true, the pdf can be appended with a signature, and the signature verification tool can identify whether the document has been modified after each signature
PdfStamper stamper = PdfStamper.createSignature(pdfReader, out, '\0', null, false);
//Read the stamp image, this image is the image of the itext package
Image image = Image.getInstance(stampOption.getImgPath());
PdfSignDto signDto = stampOption. getSignDto();
// Get the digital signature attribute object, set the attributes of the digital signature
PdfSignatureAppearance appearance = stamper. getSignatureAppearance();
BeanUtils.copyProperties(signDto,appearance);
// Calculate the diagonal coordinates (upper left, lower right)
float[] pos = calcImagePosition(image, stampOption);
//Set the signature position, page number, signature domain name, when multiple signatures are added, the signature pre-name cannot be the same
//The position of the signature is the position coordinates of the stamp relative to the pdf page, and the origin is the lower left corner of the pdf page
//The four parameters are x in the upper left corner of the stamp, y in the upper left corner of the stamp, x in the lower right corner of the stamp, and y in the lower right corner of the stamp
appearance.setVisibleSignature(new Rectangle(pos[0], pos[1], pos[2], pos[3]), stampOption.getPage(), "sig1");
appearance.setSignatureGraphic(image);
appearance.setCertificationLevel(PdfSignatureAppearance.CERTIFIED_NO_CHANGES_ALLOWED);
//Set the display mode of the stamp, the following selection is to display only the stamp (there are other modes, which can display the stamp and signature description together)
appearance.setRenderingMode(PdfSignatureAppearance.RenderingMode.GRAPHIC);
// Here itext provides 2 interfaces for signing, which can be implemented by yourself
// digest algorithm
ExternalDigest digest = new BouncyCastleDigest();
// signature algorithm
ExternalSignature signature = new PrivateKeySignature(pk, DigestAlgorithms. SHA256, null);
// Call the itext signature method to complete the pdf signature CryptoStandard.CMS signature method, it is recommended to use this
MakeSignature.signDetached(appearance, digest, signature, chain, null, null, null, 0, MakeSignature.CryptoStandard.CMS);
stamper. close();
pdfReader. close();
}
}
import lombok. Data;
/**
* @author lang.zhou
* @since 2023/8/1 13:47
*/
@Data
public class StampOption {
private float x = 0f;
private float y = 0f;
private float width = 0f;
private float height = 0f;
/**
* Number of stamped pages
*/
private int page = 1;
/** Signature image address */
private String imgPath;
private PdfSignDto signDto;
}
import lombok.Data;
import java.util.Calendar;
/**
* Signature information entity class
* @author lang.zhou
* @since 2023/8/1 13:41
*/
@Data
public class PdfSignDto {
private static final long serialVersionUID = 1L;
/** Signature time */
private Calendar signDate;
/** Digest Algorithm */
private String digestAlgorithm;
/** reason */
private String reason;
/** Place */
private String location;
/** sign */
private String signatureName;
/** Encryption Algorithm */
private String encryptionAlgorithm;
/** Signer */
private String signerName;
/** Contact information */
private String contact;
/** Amendment No */
private int revisionNumber;
}