The invention relates to a system that makes use of a mobile telephone (22) to which a user authorized to open a lock (28) has access. According to the invention, a remote management site (10) includes a database (12) of authorized users identified by the mobile telephone number thereof, as well as a data credential generator (14). The credentials are crypto acoustic credentials (CAC) in the form of single-use audio signals and are generated from digital data credentials (DDC) that are normally employed by the lock when the latter is used with a badge or a card. The system includes means (16, 18, 20) for securely transmitting the acoustic credentials to the user's telephone. The lock (22) picks up the acoustic credentials reproduced by the telephone pre-positioned near the lock and extracts the digital data credentials from the picked-up crypto acoustic credentials and, subsequently, the lock applies the thus-extracted digital data credentials to the analysis, authentication and control means of the lock.