English to German Tech/Engineering Management

from a procedure manual:

A good management system for passwords should :-

• Enforce the use of individual passwords
• Where appropriate allow users to select their own password
• Enforce a choice of quality passwords
• Enforce changes to passwords to an agreed plan
• On user select passwords change temporary passwords at first log-on
• Maintain a record of previous user passwords
• Not display passwords on the screen at entry
• Store password files separate from applications system data
• Store encrypted passwords using a one way encryption algorithm
• Alter default passwords following installation software

I can't get the meaning of the "one way encryption algorithm".

With thanks.