Network Working Group                                         E. Rescorla
Requests for Comments: 2659                                    RTFM, Inc.
Category: Experimental                                       A. Schiffman
                                                     Terisa Systems, Inc.
                                                              August 1999


                      Security Extensions For HTML

Status of this Memo

   This memo defines an Experimental Protocol for the Internet
   community.  It does not specify an Internet standard of any kind.
   Discussion and suggestions for improvement are requested.
   Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

Abstract

   This memo describes a syntax for embedding S-HTTP negotiation
   parameters in HTML documents.  S-HTTP, as described by RFC 2660,
   contains the concept of negotiation 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 specified in the form
        of RFC1485, using SGML quoting conventions 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
   implementations. 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.

           <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>

3. Security Considerations

   This entire document is about security.

4. Authors' Addresses

   Eric Rescorla
   RTFM, Inc.
   30 Newell Road, #16
   East Palo Alto, CA 94303

   Phone: (650) 328-8631
   EMail: ekr@rtfm.com


   Allan M. Schiffman
   SPYRUS/Terisa
   5303 Betsy Ross Drive
   Santa Clara, CA 95054

   Phone: (408) 327-1901
   EMail: ams@terisa.com

5. References

   [SHTTP] Rescorla, E. and A. Schiffman, "The Secure HyperText Transfer
           Protocol", RFC 2660, August 1999.

6. Full Copyright Statement

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

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   The limited permissions granted above are perpetual and will not be
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Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.