mod_auth_digest User authentication using MD5 Digest Authentication. Experimental mod_auth_digest.c auth_digest_module

This module implements HTTP Digest Authentication. However, it has not been extensively tested and is therefore marked experimental.

 AuthName AuthType Require Satisfy
Using Digest Authentication

Using MD5 Digest authentication is very simple. Simply set up authentication normally, using AuthType Digest and AuthDigestProvider instead of the normal AuthType Basic and AuthBasicProvider. Then add a AuthDigestDomain directive containing at least the root URI(s) for this protection space.

Appropriate user (text) files can be created using the htdigest tool.

Example: <Location /private/>
AuthType Digest
AuthName "private area"
AuthDigestDomain /private/ http://mirror.my.dom/private2/

AuthDigestProvider file
AuthUserFile /web/auth/.digest_pw
Require valid-user
 </Location> Note

Digest authentication provides a more secure password system than Basic authentication, but only works with supporting browsers. As of November 2002, the major browsers that support digest authentication are Opera, MS Internet Explorer (fails when used with a query string - see "Working with MS Internet Explorer" below for a workaround), Amaya, Mozilla and Netscape since version 7. Since digest authentication is not as widely implemented as basic authentication, you should use it only in controlled environments.
Working with MS Internet Explorer

The Digest authentication implementation in current Internet Explorer implementations has known issues, namely that GET requests with a query string are not RFC compliant. There are a few ways to work around this issue.

The first way is to use POST requests instead of GET requests to pass data to your program. This method is the simplest approach if your application can work with this limitation.

Since version 2.0.51 Apache also provides a workaround in the AuthDigestEnableQueryStringHack environment variable. If AuthDigestEnableQueryStringHack is set for the request, Apache will take steps to work around the MSIE bug and remove the request URI from the digest comparison. Using this method would look similar to the following.

Using Digest Authentication with MSIE: BrowserMatch "MSIE" AuthDigestEnableQueryStringHack=On

See the BrowserMatch directive for more details on conditionally setting environment variables

AuthDigestProvider Sets the authentication provider(s) for this location AuthDigestProvider On|Off|provider-name [provider-name] ... AuthDigestProvider On directory.htaccess AuthConfig

The AuthDigestProvider directive sets which provider is used to authenticate the users for this location. Setting the value to On will choose the default provider (file). Since the file provider is implemented by the mod_authn_file module, you have to make sure, that the module is present in the server.

See mod_authn_dbm and mod_authn_file for providers.

The value Off clears the provider list and sets it back to the default.

 AuthDigestQop Determines the quality-of-protection to use in digest authentication AuthDigestQop none|auth|auth-int [auth|auth-int] AuthDigestQop auth directory.htaccess AuthConfig

The AuthDigestQop directive determines the quality-of-protection to use. auth will only do authentication (username/password); auth-int is authentication plus integrity checking (an MD5 hash of the entity is also computed and checked); none will cause the module to use the old RFC-2069 digest algorithm (which does not include integrity checking). Both auth and auth-int may be specified, in which the case the browser will choose which of these to use. none should only be used if the browser for some reason does not like the challenge it receives otherwise.

auth-int is not implemented yet. AuthDigestNonceLifetime How long the server nonce is valid AuthDigestNonceLifetime seconds AuthDigestNonceLifetime 300 directory.htaccess AuthConfig

The AuthDigestNonceLifetime directive controls how long the server nonce is valid. When the client contacts the server using an expired nonce the server will send back a 401 with stale=true. If seconds is greater than 0 then it specifies the amount of time for which the nonce is valid; this should probably never be set to less than 10 seconds. If seconds is less than 0 then the nonce never expires.

AuthDigestNonceFormat Determines how the nonce is generated AuthDigestNonceFormat format directory.htaccess AuthConfig Not implemented yet. AuthDigestNcCheck Enables or disables checking of the nonce-count sent by the server AuthDigestNcCheck On|Off AuthDigestNcCheck Off server config Not implemented yet. AuthDigestAlgorithm Selects the algorithm used to calculate the challenge and response hashes in digest authentication AuthDigestAlgorithm MD5|MD5-sess AuthDigestAlgorithm MD5 directory.htaccess AuthConfig

The AuthDigestAlgorithm directive selects the algorithm used to calculate the challenge and response hashes.

MD5-sess is not correctly implemented yet. AuthDigestDomain URIs that are in the same protection space for digest authentication AuthDigestDomain URI [URI] ... directory.htaccess AuthConfig

The AuthDigestDomain directive allows you to specify one or more URIs which are in the same protection space (i.e. use the same realm and username/password info). The specified URIs are prefixes; the client will assume that all URIs "below" these are also protected by the same username/password. The URIs may be either absolute URIs (i.e. including a scheme, host, port, etc.) or relative URIs.

This directive should always be specified and contain at least the (set of) root URI(s) for this space. Omitting to do so will cause the client to send the Authorization header for every request sent to this server. Apart from increasing the size of the request, it may also have a detrimental effect on performance if AuthDigestNcCheck is on.

The URIs specified can also point to different servers, in which case clients (which understand this) will then share username/password info across multiple servers without prompting the user each time.

AuthDigestShmemSize The amount of shared memory to allocate for keeping track of clients AuthDigestShmemSize size AuthDigestShmemSize 1000 server config

The AuthDigestShmemSize directive defines the amount of shared memory, that will be allocated at the server startup for keeping track of clients. Note that the shared memory segment cannot be set less than the space that is necessary for tracking at least one client. This value is dependant on your system. If you want to find out the exact value, you may simply set AuthDigestShmemSize to the value of 0 and read the error message after trying to start the server.

The size is normally expressed in Bytes, but you may let the number follow a K or an M to express your value as KBytes or MBytes. For example, the following directives are all equivalent:

AuthDigestShmemSize 1048576
AuthDigestShmemSize 1024K
AuthDigestShmemSize 1M