Share (P2P)
"Share" uses encryption to hide the identity of who is transferring or what they are transferring. It is non-centralized so it cannot be easily shut down and it supports multiple source "swarm" downloading. All files are transferred encrypted so they must be decrypted upon download completion. In the meantime they are stored in encrypted form in a "Cache" folder. This folder is also used to allow recently downloaded files to be shared among the network based on priorities.
Encryption software
Often, the data in transit is between two entities that do not know each other - such as in the case of visiting a website. 
As establishing a relationship and securely sharing an encryption key to secure the information that will be exchanged, a set of roles, policies, and procedures to accomplish this has been developed; it is known as the public key infrastructure, or PKI. Once PKI has established a secure connection, a symmetric key can be shared between endpoints. 
A symmetric key is preferred to over the private and public keys as a symmetric cipher is much more efficient (uses less CPU cycles) than an asymmetric cipher.