XMLDSIG99

1
XML-DSIG99

• Richard D. Brown
• GlobeSet, Inc. Austin TX - U.S.
• Proposal for XML Digital Signature

2
Summary

• Motivations
• Objectives
• Specification Process
• Driving Requirements
• Syntax Proposal
• Conclusion

3
Motivations

• XML enables production and exchange of structured
  data, but this is not sufficient.
• The usefulness of such structured data depends
  upon our ability to assess its origin and
  authenticity.
• Existing binary syntaxes are not satisfactory for
  building authentication in XML applications.
• These syntaxes tend to externalize signature from
  the application logic.
• The lack of XML cryptography standard is a real
  show stopper for our industry.
• Slow down development and adoption of XML
  applications.
• Rapid proliferation of proprietary and limited
  solutions.

4
Objectives

• Define syntax and procedures for the computation,
  verification, and encoding of digital signatures
  using XML
• Signing XML document and element
• Using XML for signing WEB resources

5
Specification Process
6
Specification Process
7
Specification Process
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Requirements

• Ease signature support in XML applications and
  propose an XML alternative to binary syntaxes
• Support for digital signatures and authentication
  codes
• Support for certificate-based and account-based
  authentication schemes
• Authentication of internal and external resources
• Authentication of part or totality of a document
• Support for composite documents
• Support for extended signature functionality such
  as co-signature, endorsement, etc...

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Syntax Basics
ltCertificatesgt (certificate
information blocks) lt/Certificatesgt

• ltSignaturegt
• ltManifestgt
• (authenticated attributes)
• lt/Manifestgt
• ltValuegt
• (encoded signature value)
• lt/Valuegt
• lt/Signaturegt

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Signature Manifest
ltManifestgt (resources information block)
(other authenticated attributes) (originator
information block) (recipient information
block) (key-agreement algorithm information
block) (signature algorithm information
block) lt/Manifestgt
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Resources

• ltResourcesgt
• ltResourcegt
• ltLocator hrefresource locator/gt
• ltContentInfo typetype qualifier/gt
• ltDigestgt
• (encoded digest value)
• lt/Digestgt
• lt/Resourcegt
• lt/Resourcesgt

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Attributes

• ltAttributesgt
• ltAttribute typeresource locator
• criticalboolean/gt
• (ANY attribute value)
• lt/Attributegt
• lt/Attributesgt

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Originator and Recipient

• ltOriginatorInfogt
• (ANY identification information blocks)
• (ANY keying material information block)
• lt/OriginatorInfogt
• ltRecipientInfogt
• (ANY identification information blocks)
• (ANY keying material information block)
• lt/RecipientInfogt

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Signature and Key-agreement

• ltKeyAgreementAlgorithmgt
• (algorithm information block)
• lt/KeyAgreementAlgorithmgt
• ltSignatureAlgorithmgt
• (algorithm information block)
• lt/SignatureAlgorithmgt

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Signature Principles

• Enabling signature in XML applications
• Encapsulating arbitrary content
• Implementing endorsement
• Supporting composite documents
• Enabling one-pass processing

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Signature in XML Applications

• ltAppDoc xmlnsdsigsignature DTD URIgt
• ltAppElement idauthenticatedgt
• lt/AppElementgt
• ltdsigSignaturegt
• ...
• ltdsigResourcegt
• ltdsigLocator
  hrefauthenticated/gt
• lt/dsigSignaturegt
• lt/AppDocgt

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Encapsulating Arbitrary Content

• ltdsigPackage idauthenticatedgt
• ltdsigContentInfo typetype qualifier/gt
• ltdsigValue encodingschemegt
• (encoded value)
• lt/dsigValuegt
• lt/dsigPackagegt

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Implementing Endorsement

• ltdsigSignature idsignaturegt
• ...
• lt/dsigSignaturegt
• ltdsigSignatue idcounter-signaturegt
• ...
• ltdsigResourcegt
• ltdsigLocator hrefsignature/gt
• lt/dsigSignaturegt

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Supporting Composite Documents

• ltdsigResources idshared-resourcesgt
• ...
• lt/dsigResourcesgt
• ltdsigSignaturegt
• ...
• ltdsigResourcegt
• ltdsigLocator hrefshared-resour
  ces/gt
• ...
• lt/dsigSignaturegt
• ltdsigSignaturegt
• ...
• ltdsigResourcegt
• ltdsigLocator hrefshared-resour
  ces/gt
• ...
• lt/dsigSignaturegt

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Enabling One-Pass Processing

• ltdsigDigestAlgorithmsgt
• ltdsigAlgorithm idSHA1 typeurnnist-govs
  ha1/gt
• ltdsigAlgorithm idMD5 typeurnrsasdi-com
  md5/gt
• lt/dsigDigestAlgorithmsgt
• ltAppElement idauthenticated dsigevalSHA1
  MD5gt
• lt/AppElementgt
• ltdsigSignaturegt
• ...
• ltdsigResourcegt
• ltdsigLocator hrefauthenticated
  /gt
• ltdsigDigestgt
• ltdsigAlgorithm
  typeurnnist-govsha1/gt
• ...
• lt/dsigSignaturegt

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Algorithms

• Element Definition
• Supported Algorithms

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Algorithm Element
lt!ELEMENT Algorithm (Parameter)gt lt!ATTLIST
Algorithm id ID
IMPLIED type CDATA
REQUIRED gt lt!ELEMENT Parameter ANYgt lt!ATTLIST
Parameter type CDATA REQUIRED gt
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Algorithm Element
ltdsigAlgorithm idDSA-XHASH-SHA1
typeurnnist-govdsagt ltdsigParameter
typedigest-algorithmgt ltdsigAlgorithm
typeurnglobeset-comxhashgt
ltdsigParameter typedigest-algorithmgt
ltdsigAlgorithm typeurnnist-govSHA1/gt
lt/dsigParametergt
lt/dsigParametergt lt/dsigAlgorithmgt
ltdsigAlgorithm idDSA-XHASH-SHA1
typeurnxmldsigdsa-xhash-sha1/gt
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Supported Algorithms

• Digest Algorithms
• Key-agreement Algorithms
• Key-exchange Algorithms
• Signature Algorithms

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Digest Algorithms

• Surface String Digest Algorithms
• NIST SHA1
• Canonical Digest Algorithms
• IBM DOM-HASH
• GlobeSet XHASH

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Key-agreement Algorithms

• RSA Laboratories PKCS12 PBE

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Key-exchange Algorithms

• Static Diffie Hellman

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Signature Algorithms

• Authentication Codes
• IETF HMAC
• Public-key Signature Algorithms
• NIST DSA
• RSA Labs RSA Encryption T1
• ? ECDSA

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Conclusion

• Current Proposal
• A good start
• Enter phase 3
• Next
• First Implementations
• Standard Body
• Formalization