Encryption algorithm used for passwords in wp_users db-table?

I just upgraded to 3.2.1 from (a very old) version 2.5. I followed the manual upgrade procedure and did a db-upgrade afterwards. All worked seemingly fine as I can log in through the wp login panel, do admin stuff etc.

However, I am using the mySQL WP database as a user name database for a protected web site running Apache 2. I see that there are no apparent changes to the wp_users table as the user name and passord columns are still named “user_login” and “user_pass”. But the authentication now fails , and I suspect it is because passwords are no more md5 encrypted and possibly converted and encrypted with another scheme?

My Apache config used to look like this (truncated):

AuthType Basic
    AuthMySQLEnable on
    AuthMySQLUser _____
    AuthMySQLPassword _______
    AuthMySQLDB wordpress
    AuthMySQLUserTable wp_users
    AuthMySQLNameField user_login
    AuthMySQLPasswordField user_pass
    AuthMySQLPwEncryption md5
    AuthMySQLAuthoritative On
    require valid-user

So the question is whether the upgrade process changed the encryption of the passwords – and if Apache supports that encryption (but I realize that is not a topic in this forum).

Any help will be appreciated.