我有一个pdf / a兼容文件（我使用acrobat进行预检检查，但没有发现任何问题）。然后我使用pdfAStamper使用itextsharp对文件进行签名。有关pdfa合规性的itext签名过程有两种可能的结果。
如果签名不可见，则pdf符合pdfa标准：
stamper = PdfAStamper.CreateSignature(reader, os, '\0');
PdfSignatureAppearance appearance = stamper.SignatureAppearance;
appearance.Reason = cerReason;
appearance.Location = cerLocation;
IExternalSignature pks = new PrivateKeySignature(pk, digestAlgorithm);
MakeSignature.SignDetached(appearance, pks, chain, crlList, ocspClient, tsaClient, estimatedSize, subfilter);
如果我在Bruno Lowagie的论文ch 2.4.2中添加了可见的签名，那么预检检查会报告： 子集字体中的 CIDset不完整
在已添加的字体上报告错误：
BaseFont bfA = BaseFont.CreateFont(fntPath, BaseFont.IDENTITY_H, true);
完整代码看起来像
stamper = PdfAStamper.CreateSignature(reader, os, '\0');
PdfSignatureAppearance appearance = stamper.SignatureAppearance;
appearance.Reason = cerReason;
appearance.Location = cerLocation;
BaseFont bfA = BaseFont.CreateFont(fntPath, BaseFont.IDENTITY_H, true);
appearance.SetVisibleSignature(new Rectangle(50, 100, 400, 200), nP, "Signature");
appearance.Layer2Font = new Font(bfA, 12);
appearance.Layer2Text = cerL2Text + DateTime.Now;
appearance.SignatureRenderingMode = PdfSignatureAppearance.RenderingMode.GRAPHIC_AND_DESCRIPTION;
appearance.SignatureGraphic = Image.GetInstance(staPath);
IExternalSignature pks = new PrivateKeySignature(pk, digestAlgorithm);
MakeSignature.SignDetached(appearance, pks, chain, crlList, ocspClient, tsaClient, estimatedSize, subfilter);
最终的问题是如何使后一个例子生成符合pdfa的文件，即。如何摆脱子集字体中的 CIDset是不完整的错误？