(SQL Server) Verify Opaque Signature and Retrieve Signing Certificates

Demonstrates how to verify a PCKS7 opaque digital signature (signed data), extract the original file/data, and then extract the certificate(s) that were used to sign.

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

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

    DECLARE @crypt int
    EXEC @hr = sp_OACreate 'Chilkat.Crypt2', @crypt OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    -- Verify a PKCS7 signed-data (opaque signature) file and extract the original content to a file.
    EXEC sp_OAMethod @crypt, 'VerifyP7M', @success OUT, 'qa_data/p7m/opaqueSig.p7', 'qa_output/originalData.dat'
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @crypt, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @crypt
        RETURN
      END

    -- Alternatively, we can do it in memory...
    DECLARE @binData int
    EXEC @hr = sp_OACreate 'Chilkat.BinData', @binData OUT

    EXEC sp_OAMethod @binData, 'LoadFile', @success OUT, 'qa_data/p7m/opaqueSig.p7'
    -- Your app should check for success, but we'll skip the check for brevity..

    -- If verified, the signature is unwrapped and binData is replaced with the original data that was signed.
    EXEC sp_OAMethod @crypt, 'OpaqueVerifyBd', @success OUT, @binData
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @crypt, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @crypt
        EXEC @hr = sp_OADestroy @binData
        RETURN
      END

    -- For our testing, we signed some text, so we can get it from the binData..

    PRINT 'Original Data:'
    EXEC sp_OAMethod @binData, 'GetString', @sTmp0 OUT, 'utf-8'
    PRINT @sTmp0

    -- After any method call that verifies a signature, the crypt object will contain the certificate(s)
    -- that were used for signing (assuming the X.509 certs were available in the signature, which is typically the case).

    -- Get each signing certificate, and build the certificate chain for each.
    DECLARE @cert int
    EXEC @hr = sp_OACreate 'Chilkat.Cert', @cert OUT

    DECLARE @certChain int
    EXEC @hr = sp_OACreate 'Chilkat.CertChain', @certChain OUT

    DECLARE @numCerts int
    EXEC sp_OAGetProperty @crypt, 'NumSignerCerts', @numCerts OUT
    DECLARE @i int
    SELECT @i = 0
    WHILE @i < @numCerts
      BEGIN
        EXEC sp_OAMethod @crypt, 'LastSignerCert', @success OUT, @i, @cert
        EXEC sp_OAGetProperty @cert, 'SubjectDN', @sTmp0 OUT
        PRINT @sTmp0

        EXEC sp_OAMethod @cert, 'BuildCertChain', @success OUT, @certChain
        IF @success = 0
          BEGIN
            EXEC sp_OAGetProperty @cert, 'LastErrorText', @sTmp0 OUT
            PRINT @sTmp0
            EXEC @hr = sp_OADestroy @crypt
            EXEC @hr = sp_OADestroy @binData
            EXEC @hr = sp_OADestroy @cert
            EXEC @hr = sp_OADestroy @certChain
            RETURN
          END

        SELECT @i = @i + 1
      END

    EXEC @hr = sp_OADestroy @crypt
    EXEC @hr = sp_OADestroy @binData
    EXEC @hr = sp_OADestroy @cert
    EXEC @hr = sp_OADestroy @certChain


END
GO