SQL Server Requires Chilkat v11.7.0+

Optimizing a Signed PDF (PreserveSignatures)

See more PDF Optimization Examples

Demonstrates what happens when a signed PDF is optimized. Optimizing rewrites the document, and a rewrite breaks every existing digital signature, so with PreserveSignatures true (the default) Optimize refuses and LastErrorText says why. Setting PreserveSignatures to false allows it, and the signature that was in the file no longer verifies afterwards. "audit" is always allowed, because it changes nothing. SQL Server

--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @iTmp0 int
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

    --  This example requires the Chilkat API to have been previously unlocked.
    --  See Global Unlock Sample for sample code.

    --  The PDF used in this example is available at invoice_signed.pdf

    DECLARE @pdf int
    EXEC @hr = sp_OACreate 'Chilkat.Pdf', @pdf OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    EXEC sp_OAMethod @pdf, 'LoadFile', @success OUT, 'qa_data/pdf/invoice_signed.pdf'
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @pdf, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @pdf
        RETURN
      END


    EXEC sp_OAGetProperty @pdf, 'NumSignatures', @iTmp0 OUT
    PRINT 'signatures: ' + @iTmp0

    DECLARE @json int
    EXEC @hr = sp_OACreate 'Chilkat.JsonObject', @json OUT

    DECLARE @jsonOut int
    EXEC @hr = sp_OACreate 'Chilkat.JsonObject', @jsonOut OUT

    --  An audit changes nothing, so it is allowed on a signed PDF.
    EXEC sp_OAMethod @pdf, 'Optimize', @success OUT, 'audit', @json, @jsonOut
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @pdf, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @pdf
        EXEC @hr = sp_OADestroy @json
        EXEC @hr = sp_OADestroy @jsonOut
        RETURN
      END

    EXEC sp_OAMethod @jsonOut, 'IntOf', @iTmp0 OUT, 'estimatedSavings.total'
    PRINT 'audit ok, estimated savings: ' + @iTmp0

    --  Optimizing is refused while PreserveSignatures is true.
    EXEC sp_OAMethod @pdf, 'Optimize', @success OUT, 'optimize', @json, @jsonOut
    IF @success = 0
      BEGIN

        PRINT 'Refused while PreserveSignatures is true.'
      END

    --  Allow the rewrite.  Do this only when the signatures no longer matter -- an invoice being
    --  archived, say, where the signed original is kept elsewhere.
    EXEC sp_OASetProperty @pdf, 'PreserveSignatures', 0
    EXEC sp_OAMethod @pdf, 'Optimize', @success OUT, 'optimize', @json, @jsonOut
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @pdf, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @pdf
        EXEC @hr = sp_OADestroy @json
        EXEC @hr = sp_OADestroy @jsonOut
        RETURN
      END
    EXEC sp_OAMethod @pdf, 'WriteFile', @success OUT, 'qa_output/invoice_optimized.pdf'
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @pdf, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @pdf
        EXEC @hr = sp_OADestroy @json
        EXEC @hr = sp_OADestroy @jsonOut
        RETURN
      END

    EXEC sp_OAMethod @jsonOut, 'IntOf', @iTmp0 OUT, 'bytesSaved'
    PRINT 'optimized, bytesSaved: ' + @iTmp0

    --  The signature is still in the file, but it no longer verifies: the bytes it covered have changed.
    DECLARE @pdf2 int
    EXEC @hr = sp_OACreate 'Chilkat.Pdf', @pdf2 OUT

    EXEC sp_OAMethod @pdf2, 'LoadFile', @success OUT, 'qa_output/invoice_optimized.pdf'
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @pdf2, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @pdf
        EXEC @hr = sp_OADestroy @json
        EXEC @hr = sp_OADestroy @jsonOut
        EXEC @hr = sp_OADestroy @pdf2
        RETURN
      END

    EXEC sp_OAGetProperty @pdf2, 'NumSignatures', @iTmp0 OUT
    PRINT 'signatures after: ' + @iTmp0

    DECLARE @sigInfo int
    EXEC @hr = sp_OACreate 'Chilkat.JsonObject', @sigInfo OUT

    DECLARE @verified int
    EXEC sp_OAMethod @pdf2, 'VerifySignature', @verified OUT, 0, @sigInfo

    PRINT 'verifies after optimizing: ' + @verified

    EXEC @hr = sp_OADestroy @pdf
    EXEC @hr = sp_OADestroy @json
    EXEC @hr = sp_OADestroy @jsonOut
    EXEC @hr = sp_OADestroy @pdf2
    EXEC @hr = sp_OADestroy @sigInfo


END
GO