Java PDF文档的数字签名
是否可以为已签名的PDF文档生成数字签名?我使用以下代码为PDF文档生成数字签名Java PDF文档的数字签名,java,pdf,itext,digital-signature,pdfstamper,Java,Pdf,Itext,Digital Signature,Pdfstamper,是否可以为已签名的PDF文档生成数字签名?我使用以下代码为PDF文档生成数字签名 public void sign(String src, String dest, Certificate[] chain, PrivateKey pk, String digestAlgorithm,String provider, CryptoStandard subfilter, String reason, String location) { PdfReader rea
public void sign(String src, String dest, Certificate[] chain, PrivateKey
pk, String digestAlgorithm,String provider, CryptoStandard subfilter,
String reason, String location) {
PdfReader reader;
FileOutputStream os;
PdfStamper stamper;
try {
reader = new PdfReader(src);
File destFile = new File(dest);
String destFilePath = destFile.getAbsolutePath();
System.out.println("destFilePath=====" + destFilePath);
os = new FileOutputStream(dest);
System.out.println("File output " + os);
stamper = PdfStamper.createSignature(reader, os, '\0');
System.out.println("stamper " + stamper.getSignatureAppearance());
// Creating the appearance
PdfSignatureAppearance appearance = stamper.getSignatureAppearance();
System.out.println("Appearance " + appearance);
// appearance.setImage(Image.getInstance("F:/Unibrain/EbidUploadedFolder/" +
// "/resources/55.png"));
appearance.setImage(Image.getInstance("F:\\55.png"));
// appearance.setReason(reason);
// appearance.setLocation(location);
appearance.setVisibleSignature(new Rectangle(800, 732, 512, 780), 1, "sig");
appearance.setRenderingMode(PdfSignatureAppearance.RenderingMode.GRAPHIC_AND_DESCRIPTION);
appearance.setRenderingMode(PdfSignatureAppearance.RenderingMode.NAME_AND_DESCRIPTION);
Rectangle cropbox = reader.getCropBox(1);
float width = 250;
float height = 50;
Rectangle rectangle = new Rectangle(cropbox.getRight(width), cropbox.getBottom(), cropbox.getRight(),
cropbox.getBottom(height));
cropbox.setBorderWidth(5);
appearance.setVisibleSignature(rectangle, 1, "sig");
// Creating the signature
ExternalDigest digest = new BouncyCastleDigest();
System.out.println("digest " + digest);
ExternalSignature signature = new PrivateKeySignature(pk, digestAlgorithm, provider);
System.out.println("Signature " + signature);
MakeSignature.signDetached(appearance, digest, signature, chain, null, null, null, 0, subfilter);
} catch (Exception e) {
e.printStackTrace();
}
}
是否可以为已签名的PDF文档生成数字签名
一般来说,是的,但必须在增量更新中添加附加签名,以使预先存在的签名不失效。有关一些背景信息,请参见
对于您的代码,这意味着您必须替换该行
stamper = PdfStamper.createSignature(reader, os, '\0');
借
true
表示签名应以追加模式应用,这是在增量更新中添加更改的iText行话
此外,您必须确保在不同的表单字段中创建新签名。您的代码将签名添加到had编码字段“sig”:
如果您知道预先存在的签名的字段名称不同,那么这是可以的。否则,您可能希望将“sig”替换为null
,这使得iText为新签名创建一个唯一的字段名
上面我说“一般是”-有一个例外,如果原始签名是“不允许更改”的认证签名,则应用附加签名将破坏原始签名,因为应用它是一个更改。@Amedee Van Gasse谢谢。谢谢。以及如何使用iText库检查PDF文档是否已签名?谢谢。如何使用iText库检查PDF文档是否已签名?@VIJAYAKUMAR“如何检查PDF文档是否已使用iText签名”-cf。
stamper = PdfStamper.createSignature(reader, os, '\0', null, true);
appearance.setVisibleSignature(new Rectangle(800, 732, 512, 780), 1, "sig");