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      <a href="./?qa=734548/" class="qa-q-view-what" itemprop="url">asked</a>
      <span class="qa-q-view-when">
        <span class="qa-q-view-when-data"><time itemprop="dateCreated" datetime="2021-10-17T02:58:08+0000" title="2021-10-17T02:58:08+0000">Oct 17, 2021</time></span>
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  <h3>
    <span itemprop="name"> pdf - Getting PdfStamper to work with MemoryStreams (c#, itextsharp) </span>
  </h3>
  <div class="qa-q-view-content qa-post-content">
    <a name="734548"></a>
    <div itemprop="text">
      <p>It came to me to rework old code which signs PDF files into new one, which signs MemoryStreams (byte arrays) that come and are sent by web services. Simple, right? Well, that was yesterday. Today I just can't get it to work.</p>
      <p>This is the old code, which uses FileStreams and it works:</p>
      <pre><code>    public static string OldPdfSigner(PdfReader pdfReader, string destination, string password, string reason, string location, string pathToPfx)
    {
        using (FileStream pfxFile = new FileStream(pathToPfx, FileMode.Open, FileAccess.Read))
        {
            ...

            using (PdfStamper st = PdfStamper.CreateSignature(pdfReader, new FileStream(destination, FileMode.Create, FileAccess.Write), ''))
            {
                PdfSignatureAppearance sap = st.SignatureAppearance;
                sap.SetCrypto(key, chain, null, PdfSignatureAppearance.WINCER_SIGNED);
                sap.Reason = reason;
                sap.Location = location;
                return destination;
            }
        }
    }
</code></pre>
      <p>Below is what I've redone myself which throws System.ObjectDisposedException: Cannot access a closed Stream.</p>
      <pre><code>    public static byte[] PdfSigner(PdfReader pdfReader, string password, string reason, string location, string pathToPfx)
    {
        using (FileStream pfxFile = new FileStream(pathToPfx, FileMode.Open, FileAccess.Read))
        {
            ...

            MemoryStream outputStream = new MemoryStream();
            using (PdfStamper st = PdfStamper.CreateSignature(pdfReader, outputStream, ''))
            {
                st.Writer.CloseStream = false;
                PdfSignatureAppearance sap = st.SignatureAppearance;
                sap.SetCrypto(key, chain, null, PdfSignatureAppearance.WINCER_SIGNED);
                sap.Reason = reason;
                sap.Location = location;
                st.Close();
                outputStream.Position = 0;
                return outputStream.ToArray();
            }
        }
    }
</code></pre>
      <p>and if I comment out</p>
      <pre><code>st.Close();
</code></pre>
      <p>it creates an empty document. What am I doing wrong?</p> See Question&amp;Answers more
      detail:<a rel="nofollow" href="https://stackoverflow.com/questions/27188593/getting-pdfstamper-to-work-with-memorystreams-c-itextsharp" target="_blank">os</a>
    </div><br>
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  </div>
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      <a href="./?qa=734548/&amp;show=734549#a734549" class="qa-a-item-what" itemprop="url">answered</a>
      <span class="qa-a-item-when">
        <span class="qa-a-item-when-data"><time itemprop="dateCreated" datetime="2021-10-17T02:58:08+0000" title="2021-10-17T02:58:08+0000">Oct 17, 2021</time></span>
      </span>
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        <span class="qa-a-item-who-pad">by </span>
        <span class="qa-a-item-who-data"><span itemprop="author" itemscope="" itemtype="https://schema.org/Person"><a href="./?qa=user/%E6%B7%B1%E8%93%9D" class="qa-user-link" itemprop="url"><span itemprop="name">深蓝</span></a></span></span>
        <span class="qa-a-item-who-points">
          <span class="qa-a-item-who-points-pad">(</span><span class="qa-a-item-who-points-data">31.9m</span><span class="qa-a-item-who-points-pad"> points)</span>
        </span>
      </span>
    </span>
  </div>
  <div class="qa-a-selection">
  </div>
  <div class="qa-a-item-content qa-post-content">
    <a name="734549"></a>
    <div itemprop="text">
      <p>Not specific to your signing code, but when working with <code>MemoryStream</code> and <code>PdfStamper</code>, follow this general pattern:</p>
      <pre><code>using (MemoryStream ms = new MemoryStream()) {
  using (PdfStamper stamper = new PdfStamper(reader, ms, '', true)) {
// do stuff      
  }    
  return ms.ToArray();
}
</code></pre>
      <ul>
        <li><code>MemoryStream</code> implements <code>IDisposable</code>, so include a <code>using</code> statement.</li>
        <li>The <code>PdfStamper</code> <code>using</code> statement takes care of disposing the object, so you don't need to call <code>Close()</code>, and don't need to set the <code>CloseStream</code> property.</li>
        <li>Your code snippet is returning the byte array <strong>too soon</strong>, inside the <code>PdfStamper</code> <code>using</code> statement, so your <code>MemoryStream</code> is effectively a no-op. Return the byte array
          <strong>outside</strong> of the <code>PdfStamper</code> <code>using</code> statement, and <strong>inside</strong> the <code>MemoryStream</code> <code>using</code> statement.</li>
        <li>Generally there's no need to reset the <code>MemoryStream</code> <code>Position</code> property.</li>
        <li>Ignore the <code>PdfStamper</code> constructor above - it's from some test code I had for filling forms, and use whatever constructor/method you need to do your signing.</li>
      </ul>
    </div><br>
    <div class="signature" style="font-size:14px;overflow:hidden;margin-bottom:10px;padding-top:20px;line-height:1.6em;background:url(https://www.dismall.com/static/image/common/sigline.gif) no-repeat 0 0;">与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…</div>
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GET ./?qa=search

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</form>

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PDF - GETTING PDFSTAMPER TO WORK WITH MEMORYSTREAMS (C#, ITEXTSHARP)

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asked Oct 17, 2021 by 深蓝 (31.9m points)


PDF - GETTING PDFSTAMPER TO WORK WITH MEMORYSTREAMS (C#, ITEXTSHARP)

It came to me to rework old code which signs PDF files into new one, which signs
MemoryStreams (byte arrays) that come and are sent by web services. Simple,
right? Well, that was yesterday. Today I just can't get it to work.

This is the old code, which uses FileStreams and it works:

    public static string OldPdfSigner(PdfReader pdfReader, string destination, string password, string reason, string location, string pathToPfx)
    {
        using (FileStream pfxFile = new FileStream(pathToPfx, FileMode.Open, FileAccess.Read))
        {
            ...

            using (PdfStamper st = PdfStamper.CreateSignature(pdfReader, new FileStream(destination, FileMode.Create, FileAccess.Write), ''))
            {
                PdfSignatureAppearance sap = st.SignatureAppearance;
                sap.SetCrypto(key, chain, null, PdfSignatureAppearance.WINCER_SIGNED);
                sap.Reason = reason;
                sap.Location = location;
                return destination;
            }
        }
    }


Below is what I've redone myself which throws System.ObjectDisposedException:
Cannot access a closed Stream.

    public static byte[] PdfSigner(PdfReader pdfReader, string password, string reason, string location, string pathToPfx)
    {
        using (FileStream pfxFile = new FileStream(pathToPfx, FileMode.Open, FileAccess.Read))
        {
            ...

            MemoryStream outputStream = new MemoryStream();
            using (PdfStamper st = PdfStamper.CreateSignature(pdfReader, outputStream, ''))
            {
                st.Writer.CloseStream = false;
                PdfSignatureAppearance sap = st.SignatureAppearance;
                sap.SetCrypto(key, chain, null, PdfSignatureAppearance.WINCER_SIGNED);
                sap.Reason = reason;
                sap.Location = location;
                st.Close();
                outputStream.Position = 0;
                return outputStream.ToArray();
            }
        }
    }


and if I comment out

st.Close();


it creates an empty document. What am I doing wrong?

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
 * pdf





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1 ANSWER

0 votes

answered Oct 17, 2021 by 深蓝 (31.9m points)


Not specific to your signing code, but when working with MemoryStream and
PdfStamper, follow this general pattern:

using (MemoryStream ms = new MemoryStream()) {
  using (PdfStamper stamper = new PdfStamper(reader, ms, '', true)) {
// do stuff      
  }    
  return ms.ToArray();
}


 * MemoryStream implements IDisposable, so include a using statement.
 * The PdfStamper using statement takes care of disposing the object, so you
   don't need to call Close(), and don't need to set the CloseStream property.
 * Your code snippet is returning the byte array too soon, inside the PdfStamper
   using statement, so your MemoryStream is effectively a no-op. Return the byte
   array outside of the PdfStamper using statement, and inside the MemoryStream
   using statement.
 * Generally there's no need to reset the MemoryStream Position property.
 * Ignore the PdfStamper constructor above - it's from some test code I had for
   filling forms, and use whatever constructor/method you need to do your
   signing.


与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…




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