如何使用itextsharp C#从签名字段中删除有效性未知图标? [英] How to remove validity unknown icon from signature field using itextsharp C#?

问题描述

在计算pdf哈希之前，如何从签名字段中删除有效性未知的图标(问号).

How to remove validity unknown icon(question mark) from signature field before calculating the hash of pdf.

下面用于创建签名字段的代码.

Below code that I am using to create signature field.

PdfStamper stamper = PdfStamper.CreateSignature(reader, os, '\0');
PdfSignatureAppearance appearance = stamper.SignatureAppearance;
appearance.SignDate = DateTime.Now.AddMinutes(15);
appearance.Reason = reasonForSign;
appearance.Contact = "";
appearance.Location = locationToShowOnSignatureStamp;
appearance.Acro6Layers = false;
appearance.Image = null;
appearance.SignatureRenderingMode = PdfSignatureAppearance.RenderingMode.DESCRIPTION;
appearance.CertificationLevel = PdfSignatureAppearance.NOT_CERTIFIED;
appearance.SetVisibleSignature(new iTextSharp.text.Rectangle(10, 10, 149, 69), reader.NumberOfPages, "s1");

推荐答案

您的代码明确要求该图标:您使用

Your code explicitly requests that icon: you use

appearance.Acro6Layers = false;

这指示itext像Adobe Acrobat 5之前的版本那样创建签名外观.这包括具有肯定，不确定或否定验证结果的签名层".如果您使用

This instructs itext to create signature appearances as Adobe Acrobat up to version 5 did. This includes "layers" for signatures with positive, inconclusive, or negative validation results. If you use

appearance.Acro6Layers = true;

代替

(这是默认设置)，itext创建的签名不会使Adobe Acrobat不再显示验证结果的此类页面可视化效果.

instead (which is the default), itext creates signatures for which Adobe Acrobat won't show such on-page visualizations of the validation result anymore.

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