Hello,
We have a program which is signing files with CAPICOM. Those signed files
(detachted) can't be verified by the .NET classes. I receive "Invalid
Signature".
When I watch the signedCms.certificates(0) I see the certificate but the
CheckSignature is failing.


I see that the signed file there are linebreaks after 64 characters.
When I sign the file with .NET the linebreaks are on 74 characters.

How can I verify signed files by capicom with the .NET assemblies ?

--CAPICOM code
    SignedData = New CAPICOM.SignedDataClass
    Signer = New CAPICOM.SignerClass

    bs = BReader.ReadBytes(System.Convert.ToInt32(BReader.BaseStream.Length))

    Dim h As GCHandle = GCHandle.Alloc(bs, GCHandleType.Pinned)

    Dim ptr As System.IntPtr = Marshal.UnsafeAddrOfPinnedArrayElement(bs, 0)

    SignedData.Content = ptr

    h.Free()

    Signer.Certificate = c

    strSignString = SignedData.Sign(Signer, True,
CAPICOM.CAPICOM_ENCODING_TYPE.CAPICOM_ENCODE_BASE64)

    Dim sw As New System.IO.StreamWriter(SignedFile)
    sw.Write(strSignString)
    sw.Close()

    SignedFile.Close()
    'BReader.Close()

--.NET verify code to verify the signed file
    Dim bufferfile As Byte() = File.ReadAllBytes(strDataFileName)
      Dim strSignedFile64 As String = File.ReadAllText(strSignedFile)
      'Place signature buffer in a ContentInfo object.

      Dim contentInfo As ContentInfo = New ContentInfo(bufferfile)

      'Now Instantiate a SignedCms object with the ContentInfo above. Set
the detached content file upon which the signature is based.

      Dim signedCms As SignedCms = New SignedCms(contentInfo, True)

      'Decode buffersignature bytes into the pkcs7 object.

      signedCms.Decode(Convert.FromBase64String(strSignedFile64))

      'Now check for the detached signature; the CheckSignature function
should return a 'true' value.

      signedCms.CheckSignature(True)

IIRC CAPICOM and .NET X.509 support is not compatible - meaning CAPICOM is
doing something non-standard. But I can't remember the details.


-----
Dominick Baier (http://www.leastprivilege.com)

Developing More Secure Microsoft ASP.NET 2.0 Applications (http://www.microsoft.com/mspress/books/9989.asp)

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