The purpose of this finding is to clarify the security concerns around using passwords on the World-Wide Web. The principle advice described is that passwords SHOULD NOT be transmitted in the clear except in a few very specific cases.
This finding is an editorial draft, not yet accepted by the TAG. This finding therefore does not have any official standing and does not represent the consensus of the Technical Architecture Group at the W3C.
Security on the World-Wide Web is an important issue which needs to be addressed or mistrust of the Web will limit its growth potential. This finding describes the use of passwords on the World-Wide Web and the need to keep them secure during display, temporary storage in cookies, and in transmission over the Web.
There are sufficient technologies available to describe a clear position on password security as it relates to the World-Wide Web.
This section addresses the issue of transmitting passwords in clear text over the World-Wide Web. When a password is transmitted in clear text, it is vulnerable in many ways:
The HTTP specification specifically states that HTTP is not considered to be a secure method of user authentication (unless used in conjunction with some external secure system such as SSL).
It is estimated that between 1 and 2 percent of e-commerce transactions are related to fraud. As customers are becoming more 'net savvy', they are starting to examine web page types and are attempting to only use secure systems. Therefore, any organization that wishes to safeguard its customers' data should start with secure transfers of user login and password information.
A server SHOULD NOT solicit any passwords in clear text.
A client or browser SHOULD NOT transmit passwords in clear text.
There are some cases where it is acceptable to transmit passwords in the clear. One example is placing a password on a page is a simple way to stop web crawlers without really having to 'secure' the content. Administrators using a clear text password need to be aware that passwords used for this type of purpose SHOULD NOT re-use the same password in contexts that are more sensitive.
While it's not the purpose of this paper to do an exhaustive description of secure transfer methods on the Web, there are a few common methods used today which are easy to implement;
Digest Access Authentication[Digest]:
Digest Authentication acts as an extension to HTTP 1.0 and provides a way for authentication between parties without transmitting the password over the network. Instead the password is treated as a secret input to a digest algorithm. The resulting digest is transmitted and verified by the server. The Digest method requires that both parties have access to the same initial secret value. Many systems store passwords as a salted hash and it is not possible in practice for two parties using such systems to compute the same initial secret value.
Secure Socket Layer (SSL/TLS)
SSL/TLS is a protocol developed for transmitting private channels via the Internet. SSL/TLS works by using a private key to encrypt data that is transferred over the SSL/TLS connection. Most browsers support SSL/TLS and most sites which require credit card information use SSL/TLS today.
SOAP messages are often sent using HTTP and any SOAP message is subject to similar password security concerns. While SSL/TLS can be used to secure SOAP-based messages point to point, the issue can be more complex if SOAP intermediaries are used. The previous Good Practice advice of "A client or browser SHOULD NOT transmit passwords in clear text" applies to SOAP messages and so passwords and sensitive information SHOULD be transmitted in a secure manner and not as clear text. If confidential information is to be sent as part of the SOAP package, publishers SHOULD either use SSL/TLS or XML Encryption for sensitive data elements. Further information on security for SOAP messages can be found in Security Challenges, Threats and Countermeasures Version 1.0 [WSI] or on the OASIS Web Services Security TC home page[WSS].
HTML allows authors to create input forms. If a form field is a password, password masking SHOULD take place to protect the user from onlookers seeing what is being entered and stop anyone from later using the 'back' button to discover passwords.
<form name="form1" action="http://www.mydomain.com/myform.cgi" method="POST">
Enter Password : <input type="password" size="25"/>
User agents SHOULD use password masking when passwords are displayed in an HTML form.
This Good Practice does not contain a MUST because there are a few scenarios where password masking is not required. One example is that the user may request that the password be displayed in the clear in order to check the password as it is being entered. Another example is a password intended merely to stop web crawling and which consequently is not particularly sensitive.
[WSI]: Security Challenges, Threats and Countermeasures Version 1.0, WS-I. Available online as http://www.ws-i.org/Profiles/BasicSecurity/SecurityChallenges-1.0.pdf.