I2P initially began in 2003 as a proposed modification to Freenet. To deal with a wide range of (Gov agency) attacks, I2P is fully distributed with no centralized resources— hence there are no directory servers keeping statistics regarding the performance and reliability of routers within the network. I2P is not 100% secure, as nothing is 100% secure, but using it will provide you with meaningful security nonetheless (beyond what the older Tor software/network provides).
Content sent over I2P is encrypted through three-layer garlic encryption, used to verify the delivery of the message to the recipient. All messages passing through a tunnel are encrypted by the tunnel gateway to the tunnel endpoint, and undergo inter-router transport layer encryption along the way. You also have the ability to tunnel TCP/IP based applications (IRC, Jabber, steaming music, etc.) through the network. In fact, you can even tunnel your torrent downloads! 
While many Linux and Mint users are familiar with the older attempt of Internet protection by setting up a Tor Client/Server which is ironically found in the Linux Mint Synaptic Package repository, I2P takes that early generational effort and kicks it up another notch. Like Tor the Mint user (xyz.onion) can obtain a FREE registration domain via I2P (xyz.i2p) without paying xyz agency's and without registering with unknown nation's government's databases. One can perhaps just assume the oversight on not having the I2P repository among the Linux Mint Synaptic database of packages is just a oversight and not a deliberate attempt to torpedo Mint users security's and privacy's. The I2P download actually contains several built in security programs relating to Email, IRC, Torrents and Webservers. This information is more fully explored via the localhost pages mentioned after the I2P steps are carried out and the new user inputs that port lockup in their browser window as directed.
Here are the simple steps to add the I2P repository, install your new I2P anonymous,encrypted proxy client/server and start it up:
Step 1 Download I2P
Start by simply typing in the Linux Mint terminal:
$ sudo apt-add-repository ppa:i2p-maintainers/i2p
$ sudo apt-get update
$ sudo apt-get install i2p
This downloads and installs the I2P router on your computer.
Step 2 Start the I2P Router
Now that we have the packages downloaded and installed, we must start the service. We do this by simply typing:
$ i2prouter start
Now you can enter the following in fresh tab in your browser link window to confirm your new i2P is up and running:
 Your own free registered i2P Webserver http://pastehtml.com/view/bq9imrcjo.html