PERSEUS library is an open source technology whose aim is to secure any kind of communication streams against illegitimate or abusive eavesdropping except for Nation State Security offices, provided that a suitable, huge computing power is used (from tens of hours with a supercomputer). PERSEUS enables to provide at the same time users' needs for privacy and confidentiality while preserving the ability of security agencies (police, defense, national security...) to eavesdrop communications of really bad actors (terrorists, child pornographs...). The PERSEUS technology can be very useful in different cases:      To protect against illegal or abusive eavesdropping activity by malware on a large scale (e.g. botnets which are listening on non standard TCP ports rather than hooking keyboards for example; hooking techniques are indeed supposed to be detected by antivirus software).      To protect against private stream eavesdropping by private intelligence companies (consuming behaviour analysis, economic intelligence, non legal eavesdropping...).      To protect communications from "non democratic" states towards democratic states (e.g; journalists).      To protect professionnal of business communications in countries where cryptography use is limited or forbidden.  The interest of the PERSEUS technology lies also in the fact that TRANSEC aspect is also provided (protecting the communication channel). In other words, any data stream protected with PERSEUS looks like a lot of legitimate, unencrypted data streams. Moreover, its statistical profile is constantly changing (statistical mutation).  PERSEUS technology has been developped by Eric Filiol.