E. Rescorla, A. Schiffman
INTERNET-DRAFT                                       Terisa Systems, Inc.
<draft-ietf-wts-shtml-03.txt             March 1997 (Expires September-97)

                      Security Extensions For HTML

Status of this Memo

   This document is an Internet-Draft.  Internet-Drafts are working
   documents of the Internet Engineering Task Force (IETF), its areas,
   and its working groups.  Note that other groups may also distribute
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   ftp.isi.edu (US West Coast).

   This document was originally part of [SHTTP] but has been broken out
   to reflect it's independence from the protocol aspects of S-HTTP.

Abstract

   This memo describes a syntax for embedding S-HTTP negotiation parame-
   ters in HTML documents. S-HTTP as described by draft-ietf-wts-shttp-
   03.txt contains the concept of negotation headers which reflect the
   potential receiver of a message's preferences as to which crypto-
   graphic enhancements should be applied to the message. This document
   describes a syntax for binding these negotiation parameters to HTML
   anchors.

   1.  Introduction

   2.  Anchor Attributes

   We define the following new anchor (and form submission) attributes:

        DN -- The distinguished name of the principal for whom the
        request should be encrypted when dereferencing the anchor's
        URL.  This need not be specified, but failure to do so runs
        the risk that the client will be unable to determine the DN
        and therefore will be unable to encrypt. This should be



Rescorla, Schiffman                                              [Page 1]Internet-Draft          HTML Security Extensions          


        specified in the form of RFC1485, using SGML quoting con-
        ventions as needed.

        NONCE -- A free-format string (appropriately SGML quoted)
        which is to be included in a SHTTP-Nonce: header (after
        SGML quoting is removed) when the anchor is dereferenced.

        CRYPTOPTS -- Cryptographic option information as described
        in [SHTTP]. Specifically, the <cryptopt-list> production.

2.1.  CERTS Element

   A new CERTS HTML element is defined, which carries a (not necessarily
   related) group of certificates provided as advisory data. The element
   contents are not intended to be displayed to the user. Certificate
   groups may be provided appropriate for either PEM or PKCS-7 implemen-
   tations. Such certificates are supplied in the HTML document for the
   convenience of the recipient, who might otherwise be unable to
   retrieve the certificate (chain) corresponding to a DN specified in
   an anchor.

   The format should be the same as that of the 'Certificate-Info'
   header line, of [SHTTP] except that the <Cert-Fmt> specifier should
   be provided as the FMT attribute in the tag.

   Multiple CERTS elements are permitted; it is suggested that CERTS
   elements themselves be included in the HTML document's HEAD element
   (in the hope that the data will not be displayed by S-HTTP oblivious
   but HTML compliant browsers.)

2.2.  CRYPTOPTS Element

   Cryptopts may also be broken out into an element and referred to in
   anchors by name. The NAME attribute specifies the name by which this
   element may be referred to in a CRYPTOPTS attribute in an anchor.
   Names must have a # as the leading character.

2.3.  HTML Example

   An example of cryptographic data embedded in an anchor, proceeded by
   a certificate group is provided below. Note the SGML quoting syntax
   used to supply embedded quotation marks.









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           <CERTS FMT=PKCS-7>
           MIAGCSqGSIb3DQEHAqCAMIACAQExADCABgkqhkiG9w0BBwEAAKCAM
           IIBrTCCAUkCAgC2MA0GCSqGSIb3DQEBAgUAME0xCzAJBgNVBAYTAlVTMSAwH
           gYDVQQKExdSU0EgRGF0YSBTZWN1cml0eSwgSW5jLjEcMBoGA1UECxMTUGVyc
           29uYSBDZXJ0aWZpY2F0ZTAeFw05NDA0MDkwMDUwMzdaFw05NDA4MDIxODM4N
           TdaMGcxCzAJBgNVBAYTAlVTMSAwHgYDVQQKExdSU0EgRGF0YSBTZWN1cml0e
           SwgSW5jLjEcMBoGA1UECxMTUGVyc29uYSBDZXJ0aWZpY2F0ZTEYMBYGA1UEA
           xMPU2V0ZWMgQXN0cm9ub215MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBAMy8Q
           cW7RMrB4sTdQ8Nmb2DFmJmkWn+el+NdeamIDElX/qw9mIQu4xNj1FfepfJNx
           zPvA0OtMKhy6+bkrlyMEU8CAwEAATANBgkqhkiG9w0BAQIFAANPAAYn7jDgi
           rhiIL4wnP8nGzUisGSpsFsF4/7z2P2wqne6Qk8Cg/Dstu3RyaN78vAMGP8d8
           2H5+Ndfhi2mRp4YHiGHz0HlK6VbPfnyvS2wdjCCAccwggFRAgUCQAAAFDANB
           gkqhkiG9w0BAQIFADBfMQswCQYDVQQGEwJVUzEgMB4GA1UEChMXUlNBIERhd
           GEgU2VjdXJpdHksIEluYy4xLjAsBgNVBAsTJUxvdyBBc3N1cmFuY2UgQ2Vyd
           GlmaWNhdGlvbiBBdXRob3JpdHkwHhcNOTQwMTA3MDAwMDAwWhcNOTYwMTA3M
           jM1OTU5WjBNMQswCQYDVQQGEwJVUzEgMB4GA1UEChMXUlNBIERhdGEgU2Vjd
           XJpdHksIEluYy4xHDAaBgNVBAsTE1BlcnNvbmEgQ2VydGlmaWNhdGUwaTANB
           gkqhkiG9w0BAQEFAANYADBVAk4GqghQDa9Xi/2zAdYEqJVIcYhlLN1FpI9tX
           Q1m6zZ39PYXK8Uhoj0Es7kWRv8hC04vqkOKwndWbzVtvoHQOmP8nOkkuBi+A
           QvgFoRcgOUCAwEAATANBgkqhkiG9w0BAQIFAANhAD/5Uo7xDdp49oZm9GoNc
           PhZcW1e+nojLvHXWAU/CBkwfcR+FSf4hQ5eFu1AjYv6Wqf430Xe9Et5+jgnM
           Tiq4LnwgTdA8xQX4elJz9QzQobkE3XVOjVAtCFcmiin80RB8AAAMYAAAAAAA
           AAAAA==
           </CERTS>
           <A name=foobar
           DN="CN=Setec Astronomy, OU=Persona Certificate,
               O=&quot;RSA Data Security, Inc.&quot;, C=US"
           CRYPTOPTS="SHTTP-Privacy-Enhancements: recv-refused=encrypt;
           SHTTP-Signature-Algorithms: recv-required=NIST-DSS"
           HREF="shttp://research.nsa.gov/skipjack-holes.html">
           Don't read this. </A>



















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References
   [SHTTP] Rescorla, E., Schiffman, A.M., "The Secure HyperText Transfer
       Protocol", draft-ietf-wts-shttp-04.txt, March 1997.

Security Considerations

   This entire document is about security.

Authors' Address

Eric Rescorla <ekr@terisa.com>
Terisa Systems, Inc.
4984 El Camino Real
Los Altos, CA 94022
Phone: (415) 919-1753

Allan M. Schiffman <ams@terisa.com>
Terisa Systems, Inc.
4984 El Camino Real
Los Altos, CA 94022
Phone: (415) 919-1755