SQL Server

Create XML Digital Signature using a DSA Key

See more XML Digital Signatures Examples

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

This example requires Chilkat v9.5.0.69 or greater.

SQL Server

-- 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)
    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 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.Http', @http OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

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

    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.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.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.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