RetroShare lets you securely chat and share files with your friends and family, using a web-of-trust to authenticate peers and OpenSSL to encrypt all communication.
RetroShare also provides file sharing, chat, messages, forums, and channels.
RetroShare is the next-generation sharing network, which provides a reliable Identification and Authentication of your friends, plus an Introduction Scheme which connects you to your friends of your friends, and facilitates network growth.
RetroShare Features:
Serverless, encrypted Chat & File transfer
Multiple simultaneous downloads / uploads
Search Friends
Messages
Forums
UPnP / NAT-PMP port forwarding support
GnuPG Authentication
OpenSSL Encryption
Plugins support
Graphical User Interface is written with Qt4 toolkit
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