The problem is that password passed already encoded and there is no way to decode this. As i understand the AC use encryptDES function and generate some unique encode key for each password instance. If i change password properties like set reversable to true, crypt to false, or set the password value directly, the authorizations breaks and user can't login with his new password.
I don't see there is a way to decrypt a password in order to validate if it meets certain requirements. This something either Adobe CM provides the capability to do or not. We have integrated the login with LDAP to push all password management to the OS level managed by network group vs. the Adobe CM admin.