ssl-talk-faq.txt

Netscape公司提供的安全套接字层

    each request for "www.consensus.com" to different IP addresses. As
    Netscape Navigator does not check to see that the IP address matches
    the original domain name (reverse-IP), this will work for each
    round-robin server.

    Netscape's Navigator will also allow for some simple pattern
    matching. Netscape has documented a number of different possiblities
    in their SSL 2.0 Certificate Format web pages at
        <http://home.netscape.com/newsref/std/ssl_2.0_certificate.html>

    Note, however, none of these regular expression/pattern matching
    choices are accepted by VeriSign. In the past they have accepted
    server certificate common names with regular expressions, but these
    are no longer allowed.

    Other CAs may have different policies regarding use of regular
    expressions in common names.


5.4) When comparing a URL against the common name of the certificate,
why don't you do a reverse-DNS lookup?

    DNS is not a secure name service, and trying to treat it like one
    could be a security hole. The purpose of checking the common name
    against the URL is to make sure that at least the user's expectation
    of what site the user is visiting is not compromised.


5.5) Does Netscape require hierarchical naming (that is, distinguished
names) for its certificates?

    Yes, Netscape requires distinguished names.


5.6) Where can I get more information on certificates?

    VeriSign, the default CA (Certificate Authority) used by Netscape
    and most other WWW browsers has a FAQ at
        <http://digitalid.verisign.com/id_faqs.htm>

    There is also a good resource of links to a variety of certificate
    technical and policy issue sites available at
        <http://www.zoo.net/~marcnarc/PKI/References.htm>.


5.7) What other CAs are there besides VeriSign?

    We know of these CAs:

        EuroSign - The European Certification Authority
            <http://eurosign.com/>
        COST Computer Security Technologies <http://www.cost.se/>
        Thawte Consulting <http://www.thawte.com/certs/>

    In addition, we have heard that Entrust (Northern Telecom/NorTel),
    GE, and the US Postal Service may be announcing CA services, but
    we don't have web pages for them.


5.8) How do I set up my own Certificate Authority?

    There is some support for creating your own CA in SSLeay; there is
    information on how to integrate it with Netscape available at
        <http://wheat.webvision.com/~dhm/wvca-howto.html>


5.9) What criteria should I use in deciding between one CA and another?

    The purpose of a Certificate Authority is to bind a public key to
    the common name of the certificate, and thus assure third parties
    that some measure of care was taken to ensure that this binding
    is valid. A measure of a Certificate Authority is their "Policy
    Statement" which states what measures they take for each class of
    certificate they offer to ensure that this binding of identity
    with public key is valid.


------------------------------

6) SSL IMPLEMENTATION ISSUES

This section offers specific implementation details of different SSL
clients and servers that are not specific to the protocol.


------------------------------

6.1) NETSCAPE QUESTIONS

Sub-section 6.1 is maintained by Eric Greenberg <[e-mail]> --
any comments or questions should be sent to him.


6.1.1) Will SSL 3.0 functionality be available to Java applets via the
Netscape plug-in interfaces available as part of LiveConnect in Netscape
3.0?

    It will not be in 3.0, but Netscape is looking at it for a future
    release.


6.1.2) Does the Netscape browser cache on disk data that has been sent
over by https?

    Navigator 3.0 has an option to allow caching of data fetched
    over SSL connections. The default setting is to not cache data.

    In Navigator 2.0, documents fetched using SSL were cached in the
    same way as non-SSL documents. You could use the "Pragma: no-cache"
    HTTP header to disable caching for a particular page. In Navigator
    1.0 documents fetched with SSL were not cached.


6.1.3) Is the cached data encrypted using some key?

    No, Netscape has never encrypted documents that are stored in the
    cache.


6.1.4) The Help Information for Netscape's Enterprise 2.0 server
indicates that the server supports 6 ciphers for SSL 2.0 and 6
ciphers for SSL 3.0. However, the Encryption|Security Preferences
menu in the server Manager displays only 2 choices for SSL 2.0 and 3
choices for SSL 3.0. How can I select the other choices?

    You have the export version of the server which supports only the
    ciphers displayed. If you want to use the others, you must
    use the US-only (non-export) version.


6.1.5) What mechanisms will be available for "aging" passphrases used
to unlock certificate databases. Will these be configurable?

    At this point no mechanisms exist in Netcape's Navigator, and
    therefore aging is not configurable. Presumably the future of
    personal certificate databases requires smartcards, but until that
    time aging is an application specific function.


6.1.6) Is Netscape adopting any open standards for APIs in these
areas? Is Netscape working with any standards bodies or other groups on
such APIs? Is there any word on the emerging security architectures,
such as Microsoft's Crypto-API, RSA's LOCT, or GSS-API?

    Netscape has been participating in a number of working groups
    interested in standard security APIs. At this point Netscape has not
    adopted a single security API approach or committed to a specific
    proposed standard security API. Eventually Netscape may use all or
    some subset (or perhaps none) of these specific architectures.
    Netscape welcomes customer comments or suggestions on this topic.


6.1.7) Does Netscape use "regular" RSA libraries (such as BSAFE) or
"custom" RSA code?  More specifically, is Netscape using BSAFE 3.0?

    BSAFE 3.0 is currently being integrated in all of Netscape's
    products. Netscape has modified portions of the BSAFE API to improve
    efficiency in the heavy load environment of their products, but
    Netscape continues to integrate the upgraded code from RSA as
    soon as practical.


6.1.8) Will Netscape client authentication be interoperable with
other SSL implementations?

    We can't speak to which specific implementations have been testing
    against our server. Netscape does currently offer an
    interoperability test server that has been used to test conformance
    with many other implementations of SSL 3.0. This server is located
    at
        <https://www3.netscape.com/>


6.1.9) How might Netscape offer more "cryptographic flexibility,"
such as selection of algorithms and authentication without
encryption?

    SSL 3.0 allows for authentication-only (and even encrypt only)
    methods. Algorithm selection is negotiated by the client and the
    server. The Navigators "Security Preferences:General" allow the
    user to define per algorithm overrides for each SSL2 or SSL3
    session.


6.1.10) Isn't encrypt-only SSL open to "man-in-the-middle" attacks?

    Yes, even though SSL 3.0 supports encrypt-only (through the
    SSL_DH_anon_WITH_DES_CBC_SHA ciphersuite), there are many possible
    attacks against it, and we recommend against using it. SSL *MUST*
    have strong authentication at the record layer or it becomes open to
    some attacks. It doesn't matter if the application has
    authentication at the application layer.


6.1.11) Are the 512-bit RSA keys used by exportable applications
generated on the fly by the server? How often are they changed? (The
spec recommends every 500 transactions.) Does the Netscape server
take care of changing them automatically?

    In the Netscape 2.0 servers, if the server's public key is longer
    than 512 bits, it generates a temporary 512-bit export key at
    start-up time. This key is regenerated only when the server is
    restarted. Netscape does it this way because generating a key can
    take several seconds.

    The 500 transaction limit is only a guideline and largely depends on
    how valuable the information being encrypted is.  For information
    for which you worry about how often the key is regenerated you
    should probably be using something stronger than a 40-bit symmetric
    key anyway.


6.1.12) What are the plans for mechanisms for adding root keys and
accepting root certificates for future use?

    Root keys for CA (Certificate Authority) certificates are loaded
    through an automatic process using an SSL connection to a previously
    unknown CA. Also new releases of the Navigator have added additional
    CA root keys.

    Presumably in the future loading a root cert object through a local
    process, such as from disk, LDAP, or other out-of-band mechanism,
    will be a supported addition or in place of the present method of
    connecting to a trusted server and downloading the certificate
    chain.


6.1.13) With regard to the certificate extensions documentation at
<http://home.netscape.com/eng/security/certs.html> what X.509v3
certificate extensions will the release 3.0 Navigator use?

    The following extensions are supported in some way by Navigator 3.0:

        netscape-revocation-url
        netscape-ca-revocation-url

    A button will appear on the Document Info page for server's whose
    certificate (or CA's cert) contains these extension. When the button
    is pressed the CA will be queried via HTTP GET, and will display a
    dialog to indicate to the user if the cert is good or not.

        netscape-cert-renewal-url

    If a user attempts to use a client certificate that has expired, a
    dialog will be displayed warning them that their cert has expired,
    and if this extension exists, a button will be on the dialog that
    will bring up a window displaying the URL.

        netscape-ca-policy-url

    A button will be displayed on the Document Info for server certs
    that contain this extension. When press a window displaying the
    policy URL will be opened.

        netscape-ssl-server-name

    This extension is used in place of the common name when it exists to
    verify the domain name of the site.

        netscape-comment

    A Netscape-specific place for comments.


6.1.14) Does the Navigator actually use the revocation URL
or CA revocation URL?

    There is no automatic revocation check. As mentioned above, a button
    allowing manual checks is displayed on the Document Info page. This
    feature was added because some people needed revocation, but we did
    not have time to support full CRLs. In a future release we will
    support CRLs, and possibly other forms of revocation technology.


------------------------------

6.2) MICROSOFT QUESTIONS

The text for sub-section 6.2 was grabbed from various documents
found at
        <http://www.microsoft.com/intdev/security/>


6.2.1) Which of Microsoft's products will support SSL?

    Internet Explorer 3.0 provides support for SSL versions 2.0 and 3.0
    and for Private Communication Technology (PCT) version 1.0. It will
    include support for the Transport Layer Security Protocol (TLS),
    which is being considered by IETF.


6.2.2) Which Microsoft products support Client Authentication?

    Client authentication as implemented by Microsoft Internet Explorer
    3.0 is interoperable with popular Web servers that support secure
    sockets layer (SSL) 3.0 client authentication.

    Microsoft is working to extend the complete set of technology
    components necessary for webmasters to incorporate client
    authentication in their Web applications. This includes extending
    Windows NT(r) Server operating system support for challenge and
    response and the SSL 2.0 protocol used by Microsoft Internet
    Information Server to also include support for client authentication
    through the SSL 3.0 protocol.


------------------------------

7) SSL TOOKIT QUESTIONS

This section offers specific details of different SSL development
toolkits that are not specific to the protocol.


------------------------------

7.1) SSLREF QUESTIONS

This subsction contains information on SSLRef 3.0 which was
codeveloped by Netscape Communications Corp. of Mountain View,
California <http://home.netscape.com/> and Consensus Development
Corporation of Berkeley, California <http://www.consensus.com/>.


7.1.1) What is SSLRef 3.0?

    SSLRef 3.0 is a reference implementation of the SSL (Secure Sockets