Redmine User Auth module connects to Redmine database to authenticate users.

Password entered during Jenkins login is hashed, and compared with hash stored in database in "passField".
Hash algorithm depends on Redmine version:

1. in Redmine 1.2.0 and above, the algorithm is: SHA1(salt + SHA1(clear_text_passwd))
2. in Redmine 1.1.x and lower, there is no salt, so the algorithm is: SHA1(clear_text_passwd)