PDF签署PDFBox的带锁

Question

我想用锁来签名PDF。我使用PDFBox的2.0.9

我要实现的流程是：

• 我将创建一个文档与表单字段
• 我想在文件上签字，但排除表单域
• 签署这份文件后，我想改变这种字段的值
• 我将不排除再次登录

因此，如果有人重新编辑该表单字段，则Adobe Reader应该说，这份文件已经改变。

"Lock" dictionary in signature field is the reason of broken signature after signing

我从这里得到了示例代码和我写了这一个：

PDSignatureField signatureField = getSignatureField(pdDocument, pdSignature);
if (signatureField != null) {
    COSDictionary lockDict = new COSDictionary();
    lockDict.setItem(COSName.TYPE, COS_NAME_SIG_FIELD_LOCK);
    lockDict.setItem(COS_NAME_ACTION, COS_NAME_EXCLUDE);

    COSArray lockFields = new COSArray();
    lockFields.add(new COSString("textbox1"));

    lockDict.setItem(COS_NAME_FIELDS, lockFields);

    signatureField.getCOSObject().setItem(COS_NAME_LOCK, lockDict);

    COSDictionary transformParams = new COSDictionary(lockDict);
    transformParams.setItem(COSName.TYPE, COSName.getPDFName("TransformParams"));
    transformParams.setItem(COSName.V, COSName.getPDFName("1.2"));
    transformParams.setDirect(true);
    COSDictionary sigRef = new COSDictionary();
    sigRef.setItem(COSName.TYPE, COSName.getPDFName("SigRef"));
    sigRef.setItem(COSName.getPDFName("TransformParams"), transformParams);
    sigRef.setItem(COSName.getPDFName("TransformMethod"), COSName.getPDFName("FieldMDP"));
    //sigRef.setItem(COSName.getPDFName("Data"), pdDocument.getDocumentCatalog());
    sigRef.setDirect(true);
    COSArray referenceArray = new COSArray();
    referenceArray.add(sigRef);
    pdSignature.getCOSObject().setItem(COSName.getPDFName("Reference"), referenceArray);

}

我可以注册，更改字段值，并再次登录和签名都还好。问题是，当我第二个签名后更改字段的值，签名仍然有效。我期待的是最后一次更改后，第二个签名必须是无效的。

Answer 1

问题是我的代码，因为这个代码将不包括每次。当我编写象下面这样（我的第一个签名的名字是签名1），一切都变得正常预期。

    public static final COSName COS_NAME_LOCK = COSName.getPDFName("Lock");
    public static final COSName COS_NAME_ACTION = COSName.getPDFName("Action");
    public static final COSName COS_NAME_ALL = COSName.getPDFName("All");
    public static final COSName COS_NAME_INCLUDE = COSName.getPDFName("Include");
    public static final COSName COS_NAME_EXCLUDE = COSName.getPDFName("Exclude");
    public static final COSName COS_NAME_FIELDS = COSName.getPDFName("Fields");
    public static final COSName COS_NAME_SIG_FIELD_LOCK = COSName.getPDFName("SigFieldLock");


        PDSignatureField signatureField = getSignatureField(pdDocument, pdSignature);
        if (signatureField != null) {
            COSDictionary lockDict = new COSDictionary();
            lockDict.setItem(COSName.TYPE, COS_NAME_SIG_FIELD_LOCK);
            lockDict.setItem(COS_NAME_ACTION, COS_NAME_EXCLUDE);

            COSArray lockFields = new COSArray();
            if (pdSignature.getName().equals("Signature1")) {
                lockFields.add(new COSString("textbox1"));
            }

            lockDict.setItem(COS_NAME_FIELDS, lockFields);

            signatureField.getCOSObject().setItem(COS_NAME_LOCK, lockDict);

            COSDictionary transformParams = new COSDictionary(lockDict);
            transformParams.setItem(COSName.TYPE, COSName.getPDFName("TransformParams"));
            transformParams.setItem(COSName.V, COSName.getPDFName("1.2"));
            transformParams.setDirect(true);
            COSDictionary sigRef = new COSDictionary();
            sigRef.setItem(COSName.TYPE, COSName.getPDFName("SigRef"));
            sigRef.setItem(COSName.getPDFName("TransformParams"), transformParams);
            sigRef.setItem(COSName.getPDFName("TransformMethod"), COSName.getPDFName("FieldMDP"));
            sigRef.setDirect(true);
            COSArray referenceArray = new COSArray();
            referenceArray.add(sigRef);
            pdSignature.getCOSObject().setItem(COSName.getPDFName("Reference"), referenceArray);

        }