Implementation Of XML DIGITAL SIGNATURES Using Microsoft .NET

1. Implementation Of XML DIGITAL SIGNATURES Using Microsoft .NET

2. PRESENTED BY : NANIDITA SRIVASTAVA NEEHARIKA KOLLA MOUNIKA VALLABHANENI

3. MAIN FOCUS OF THE PROJECT: 1.Feature of XML digital signatures 2.XML documents and XML digital signatures in brief. 3.Creation of windows based application using .NET & C# 4.Application lets user encode and sign specific parts of an XML file. 5.Presenting 3 test cases where user changes the or the key…….and verification produces invalid results

4. Digital Signatures A digital signature is an electronic signature that can be used to authenticate the identity of the sender of a message or the signer of a document.

5. XML Digital Signatures • Digital signatures designed for use in XML transactions. • Joint effort between the World Wide Web Consortium (W3C) and Internet Engineering Task Force (IETF) • Similarities and Differences with Standard Digital Signatures • Similarities • Authentication • Data integrity • Support for non-repudiation • Differences • Support for Web based nature of todays transactions

6. What is XML XML is a markup language for documents containing structured information. XML was created so that richly structured documents could be used over the web. The only viable alternatives, HTML as it comes bound with a set of semantics and does not provide arbitrary structure. A sample XML document <?xml version="1.0" encoding="utf8"?> <Companies> <CompanyA> <DocumentInformation> <documentName namingSystem="POSC">Sample 3</documentName> </ DocumentInformation > <BusinessAssociate> <AuthorizedPerson> <name>Marvin P. Mooney</name> <title>Vice President of Drilling Operations</title> </AuthorizedPerson> </BusinessAssociate> <LegalDescription> <townshipNumber direction="N">50</townshipNumber> </LegalDescription> </CompanyA> </ Companies >

7. Why XML is important (Use in Web Services) Web services are application programming interfaces (API) that can be accessed over a network, such as the Internet, and executed on a remote system. Generic Web Service Architecture

8. Use of XML Digital Signatures in Web Services • Non-repudiation and integrity assume alarming dimensions in a web service-driven world. Suppose that a confidential XML document is populated by services A and B, and is passed on to service E by C and D. To make things worse, let's assume that these services are provided by different systems/vendors across the Net! Now, how can the end consumer service E ensure the authenticity of the sender services A and B? What guarantee does it have that the XML data passed on from A and B has not been modified during the transit or by other malicious services? With hacking becoming a common phenomenon on the Internet, it is quite possible that unauthorized services will come to life all of a sudden from the network and start consuming confidential business data. How can we make sure that the sender services A and B take full responsibility for what is contained in the XML document? Example

9. The Components of an XML Signature

10. XML Digital Signatures An XML signature can sign more than one type of resource. For example, a single XML signature might cover character-encoded data (HTML), binary-encoded data (a JPG), XML-encoded data, and a specific section of an XML file. Steps to create XML Digital Signatures • Determine which resources are to be signed. • This will take the form of identifying the resources through a Uniform Resource Identifier (URI). • "http://www.abccompany.com/index.html" would reference an HTML page on the Web • "http://www.abccompany.com/logo.gif" would reference a GIF image on the Web • . Calculate the digest of each resource. Create • Reference element • DigestValue element • DigestMethod element • Collect the Reference elements. Create • SignedInfo element • CanonicalizationMethod • SignatureMethod

11. Steps to create XML Digital Signatures • Signing • SignatureValue element. • Add key information • KeyInfo element • Enclose in a Signature element • Signature element Steps to verify XML Digital Signatures Recalculate the digest of the <SignedInfo> element (using the digest algorithm specified in the <SignatureMethod> element) and use the public verification key to verify that the value of the <SignatureValue> element is correct for the digest of the <SignedInfo> element. If this step passes, recalculate the digests of the references contained within the <SignedInfo> element and compare them to the digest values expressed in each <Reference> element's corresponding <DigestValue> element.

12. Concepts central to XML Digital Signature Specifications • X-PATH Transforms • Specifies which content is to be signed. • Evaluates Expressions to filter out the nodes. Example child::* • In our project Refence.AddTransform(CreateXPathTransform("ancestor-or-self::CompanyA")) • Cannonicalization • Important to take care of formatting differences between two logically similar documents. • The canonicalization algorithm used normally changes the character encding to • UTF-8,Change the line breaks to #Xa etc. • In our project SignedXml.XmlDsigCanonicalizationUrl field specifies this • Types of XML digital Signatures • Enveloped • Enveloping • Detached

13. .Net Implementation of XML Digital Signatures • The System.Security.Cryptography namespace in .NET provides cryptographic services, including secure encoding and decoding of data, as well as many other operations, such as hashing, random number generation, and message authentication. The hierarchy of the classes found in the framework are as follows • Algorithm type classes (Abstract) • SymmetricAlgorithm or HashAlgorithm • Abstract classes • Algorithm class (Abstract) • Inherits from an algorithm type class • RC2 or SHA1 • Abstract • Implementation of an algorithm class • These inherits from an algorithm class • RC2CryptoServiceProvider or SHA1 Managed • Fully implemented

14. Crypto Service Providers used in our project DESCryptoServiceProvider for Encryption-Implements Data Encryption Standard (DES) algorithm used in CBC mode RSACryptoServiceProvider for Signing -Implements RSA algorithm Project Implementation • Windows based application (C# ) • User selects an XML file • Application encodes and Signs the file • Application can decode and Verify the Signature Key Creation Use of sn.exe utility Created key stored in an XML file Decryption Create a crypto key from an XML file

15. Code Snippet XmlDocument xmldoc=new XmlDocument(); xmldoc.LoadXml(xml); // Get the key pair from the key store. CspParameters parms=new CspParameters(1); // PROV_RSA_FULL parms.Flags=CspProviderFlags.UseMachineKeyStore; // Use Machine store parms.KeyContainerName=keyContainerName; parms.KeyNumber=2; RSACryptoServiceProvider csp=new RSACryptoServiceProvider(parms); // Creating the XML signing object. SignedXml sxml=new SignedXml(xmldoc); sxml.SigningKey=csp; // Set the canonicalization method for the document. sxml.SignedInfo.CanonicalizationMethod=SignedXml.XmlDsigCanonicalizationUrl; // No comments. // Create an empty reference (not enveloped) for the XPath transformation. Reference r=new Reference(""); r.AddTransform(CreateXPathTransform("ancestor-or-self::CompanyA")); sxml.AddReference(r); // Add the reference to the SignedXml object. sxml.AddReference(r); // Compute the signature. sxml.ComputeSignature(); // Get the signature XML and add it to the document element. XmlElement sig=sxml.GetXml(); xmldoc.DocumentElement.AppendChild(sig); // Write-out formatted signed XML. StringBuilder sb=new StringBuilder(); StringWriter tw=new StringWriter(sb); XmlTextWriter writer=new XmlTextWriter(tw); writer.Formatting=Formatting.Indented;

17. DEMOThanks