(SQL Server) Create XML Digital Signature using a DSA Key

Demonstrates how to create an XML digital signature using a DSA key.

This example requires Chilkat v9.5.0.69 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
    DECLARE @sTmp0 nvarchar(4000)
    -- This example requires the Chilkat API to have been previously unlocked.
    -- See Global Unlock Sample for sample code.

    -- The XML to be signed in this example contains the following:

    -- <?xml version="1.0" encoding="UTF-8" standalone="no"?>
    -- <Envelope>
    --   <Header>
    --     <Security>
    --     </Security>
    --   </Header>
    --   <Body Id="abc">
    --     <z:FooBar xmlns:z="https://www.example-code.com"/>
    --   </Body>
    -- </Envelope>

    -- The above XML is available at https://www.chilkatsoft.com/exampleData/xmlToSign.xml
    -- Fetch the XML and then sign it..

    DECLARE @url nvarchar(4000)
    SELECT @url = 'https://www.chilkatsoft.com/exampleData/xmlToSign.xml'
    DECLARE @http int
    EXEC @hr = sp_OACreate 'Chilkat_9_5_0.Http', @http OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    DECLARE @sbXml int
    EXEC @hr = sp_OACreate 'Chilkat_9_5_0.StringBuilder', @sbXml OUT

    DECLARE @success int
    EXEC sp_OAMethod @http, 'QuickGetSb', @success OUT, @url, @sbXml
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @http, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @http
        EXEC @hr = sp_OADestroy @sbXml
        RETURN
      END

    -- This example uses a DSA private key for signing.  
    -- There are many ways of getting an DSA private key using Chilkat.  This example
    -- will load it from an encrypted PEM file.

    -- In case you would like to use it, I put the DSA private key PEM file here:
    -- https://www.chilkatsoft.com/exampleData/dsa1024_secret.zip
    -- The password is "secret".
    DECLARE @dsaKey int
    EXEC @hr = sp_OACreate 'Chilkat_9_5_0.PrivateKey', @dsaKey OUT

    EXEC sp_OAMethod @dsaKey, 'LoadEncryptedPemFile', @success OUT, 'qa_data/dsa/dsa1024_secret.pem', 'secret'
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @dsaKey, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @http
        EXEC @hr = sp_OADestroy @sbXml
        EXEC @hr = sp_OADestroy @dsaKey
        RETURN
      END

    -- To create the XML digital signature (i.e. embed the signature within
    -- the XML), first specify what is desired, then call the method to 
    -- create the XML signature.
    -- 
    -- For example, the application must provide the following:
    --     - Where to put the signature.
    --     - What to sign.
    --     - The algorithms to be used.
    --     - The key to be used for signing.
    -- 

    DECLARE @xmlSigGen int
    EXEC @hr = sp_OACreate 'Chilkat_9_5_0.XmlDSigGen', @xmlSigGen OUT

    -- In this example, we're going to put the signature within the Security element.
    -- To specify the location, set the SigLocation property to the XML path to this element,
    -- using vertical bar characters to separate tags.
    EXEC sp_OASetProperty @xmlSigGen, 'SigLocation', 'Envelope|Header|Security'

    -- An XML digital signature contains one or more references.  These can be references to the parts
    -- of the XML document to be signed (a same document reference), or can be external references.
    -- This example will add a single same-document reference.  We'll add a reference to the XML fragment
    -- at Body, which is indicated by providing the value of the "ID" attribute (where "ID" is case
    -- insensitive).  In this case, we specify "abc" because Body has an Id="abc".
    -- This causes the <Body> ... </Body> XML fragment to be signed.
    -- 
    -- For each same-document reference, we must also indicate the hash algorithm and XML canonicalization
    -- algorithm to be used.  For this example we'll choose SHA1 and Exclusive XML Canonicalization.
    EXEC sp_OAMethod @xmlSigGen, 'AddSameDocRef', @success OUT, 'abc', 'sha1', 'EXCL_C14N', '', ''

    -- Provide the DSA key to be used for signing:
    EXEC sp_OAMethod @xmlSigGen, 'SetPrivateKey', @success OUT, @dsaKey

    -- We're leaving the following properties at their default values:
    -- 
    --    - SigNamespacePrefix (default is "ds")
    --    - SignedInfoCanonAlg  (default is EXCL_C14N)
    --    - KeyInfoType (default is "KeyValue", where the DSA public key is included in the Signature)

    -- Note: Each Reference has it's own specified algorithms for XML canonicalization and hashing,
    -- and the actual signature part (the SignedInfo) has it's own hash/canonicalization algorithm.
    -- They may or may not be the same.  In this example, we use Exclusive XML Canonicalization and SHA1 throughout.

    -- The default SignedInfoDigestMethod is sha256, which is a good choice.  This example will
    -- change it to sha1.
    EXEC sp_OASetProperty @xmlSigGen, 'SignedInfoDigestMethod', 'sha1'

    -- OK, everything's specified, so let's create the XML digital signature:
    -- This in-place signs the XML.  If successful, sbXml will contain the 
    -- XML with the digital signature at the specified location.
    EXEC sp_OAMethod @xmlSigGen, 'CreateXmlDSigSb', @success OUT, @sbXml
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @xmlSigGen, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @http
        EXEC @hr = sp_OADestroy @sbXml
        EXEC @hr = sp_OADestroy @dsaKey
        EXEC @hr = sp_OADestroy @xmlSigGen
        RETURN
      END

    -- Examine the signed XML:
    EXEC sp_OAMethod @sbXml, 'GetAsString', @sTmp0 OUT
    PRINT @sTmp0

    -- Below is the signed XML that is produced.
    -- Chilkat emits the Signature in compact form on a single line.  Whitespace in XML signatures
    -- matters.  Chilkat's opinion is that writing the Signature without whitespace minimizes the chance
    -- for problems with whatever software might be verifying the signature.

    -- <?xml version="1.0" encoding="UTF-8" standalone="no"?>
    -- <Envelope>
    --   <Header>
    --     <Security>
    --     <ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#"><ds:SignedInfo><ds:CanonicalizationMethod Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/><ds:SignatureMethod Algorithm="http://www.w3.org/2000/09/xmldsig#dsa-sha1"/><ds:Reference URI="#abc"><ds:Transforms><ds:Transform Algorithm="http://www.w3.org/2001/10/xml-exc-c14n#"/></ds:Transforms><ds:DigestMethod Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/><ds:DigestValue>77X3L6odxTBow1W1dIiqZW1foow=</ds:DigestValue></ds:Reference></ds:SignedInfo><ds:SignatureValue>Ci/KiAqoQLvNyK94n8TJwdJ6dVpIIy8tJg+9s8utmB92cW8lTd+U7g==</ds:SignatureValue><ds:KeyInfo><ds:KeyValue><ds:DSAKeyValue><ds:P>AN+Af9FvnqYl84Own8m/MHza9vVFEbpySOiWyeIM8diDjaES9i+UykaX9BGc0oaRJHtrHhe+gboMBGHfP+gYcgbqzeyVCi2kHghRD/TK7uI4jN8Yv8tfM6AO0QrDFfxFq4IV+qTZbSoCkbWaopQ+kEOY6B4btFxJ1YuE48mExMZ3</ds:P><ds:Q>AOCv5pwf4kvMW37Yzt0iH6URKOlD</ds:Q><ds:G>FO3eoDcpuU9Z25OQGFtC+M2ifczcKyRkFwTauGR3mIw0wePPiu3Ocr7A81SA8GQ9x3hWO5jyP//jL3jxYy8fgBg2RXwiic3nwT2rZfu50g6tPUpz1stKz/+Mxjulo6XuaMSOWwjU021IxVMzxQ1/L8QiwiIrwxvfQOaMY8HJgvw=</ds:G><ds:Y>JJmZQvWtrZ+Nb2YV47SfGAave8uOIedGlmg+CseoqKZC2aFcWM6kR0giUwQx834dhxQScRhqzxFxQPk/x+5hyG8LQbXW+BELmT1BiyodobYUAet4rSIt4EU4KU0iYw1drpcWT1jqI07l5xNi28heYSfSF5Odv2qwXxVKDSEeEkM=</ds:Y></ds:DSAKeyValue></ds:KeyValue></ds:KeyInfo></ds:Signature></Security>
    --   </Header>
    --   <Body Id="abc">
    --     <z:FooBar xmlns:z="https://www.example-code.com"/>
    --   </Body>
    -- </Envelope>

    -- The above signed XML contains the DSA public key in the DSAKeyValue fragment (within the ds:KeyInfo).
    -- The signature can easily be verified like this:

    DECLARE @verifier int
    EXEC @hr = sp_OACreate 'Chilkat_9_5_0.XmlDSig', @verifier OUT

    -- First load the XML containing the signature(s) to be verified.
    EXEC sp_OAMethod @verifier, 'LoadSignatureSb', @success OUT, @sbXml
    IF @success <> 1
      BEGIN
        EXEC sp_OAGetProperty @verifier, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @http
        EXEC @hr = sp_OADestroy @sbXml
        EXEC @hr = sp_OADestroy @dsaKey
        EXEC @hr = sp_OADestroy @xmlSigGen
        EXEC @hr = sp_OADestroy @verifier
        RETURN
      END

    DECLARE @bVerified int
    EXEC sp_OAMethod @verifier, 'VerifySignature', @bVerified OUT, 1
    IF @bVerified <> 1
      BEGIN
        EXEC sp_OAGetProperty @verifier, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
      END

    PRINT 'Signature verified = ' + @bVerified

    EXEC @hr = sp_OADestroy @http
    EXEC @hr = sp_OADestroy @sbXml
    EXEC @hr = sp_OADestroy @dsaKey
    EXEC @hr = sp_OADestroy @xmlSigGen
    EXEC @hr = sp_OADestroy @verifier


END
GO