Updated theoretical description of link establishment. Finally.

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Mark Qvist 2021-05-17 14:57:31 +02:00
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Reticulum Network Stack Documentation Reticulum Network Stack Manual
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Welcome to the documentation for Reticulum. This document aims to provide you Welcome to the manual for Reticulum. This document aims to provide you
with all the information you need to understand Reticulum, develop programs with all the information you need to understand Reticulum, develop programs
using it, or to participate in the development of Reticulum itself. using it, or to participate in the development of Reticulum itself.

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* | When a node in the network wants to establish verified connectivity with another node, it * | When a node in the network wants to establish verified connectivity with another node, it
will create a *link request* packet, and broadcast it. will randomly generate a new X25519 private/public key pair. It then creates a *link request*
packet, and broadcast it.
* | The *link request* packet contains the destination hash *Hd* , and an asymmetrically encrypted * | The *link request* is addressed to the destination hash of the desired destination, and
part containing the following data: The source hash *Hs* , a symmetric key *Lk* , a truncated contains the following data: The newly generated X25519 public key *LKi*. The contents
hash of a random number *Hr* , and a signature *S* of the plaintext values of *Hd* , *Hs* , *Lk* and *Hr*. are encrypted with the RSA public key of the destination and tramsitted over the network.
* | The broadcasted packet will be directed through the network according to the rules laid out * | The broadcasted packet will be directed through the network according to the rules laid out
previously. previously.
@ -415,31 +416,33 @@ of hops, where information will be exchanged between two nodes.
* | Any node that forwards the link request will store a *link id* in its *link table* , along with the * | Any node that forwards the link request will store a *link id* in its *link table* , along with the
amount of hops the packet had taken when received. The link id is a hash of the entire link amount of hops the packet had taken when received. The link id is a hash of the entire link
request packet. If the path is not *proven* within some set amount of time, the entry will be request packet. If the path is not *proven* within some set amount of time, the entry will be
dropped from the table again. dropped from the *link table* again.
* | When the destination receives the link request packet, it will decide whether to accept the * | When the destination receives the link request packet, it will decrypt it and decide whether to
request. If it is accepted, it will create a special packet called a *proof*. A *proof* is a simple accept the request. If it is accepted, the destination will also generate a new X25519 private/public
construct, consisting of a truncated hash of the message that needs to be proven, and a key pair, and perform a Diffie Hellman Key Exchange, deriving a new symmetric key that will be used
signature (made by the destinations private key) of this hash. This *proof* effectively verifies to encrypt the channel, once it has been established.
that the intended recipient got the packet, and also serves to verify the discovered path
through the network. Since the *proof* hash matches the *path id* in the intermediary nodes * | A *link proof* packet is now constructed and transmitted over the network. This packet is
*path tables* , the intermediary nodes can forward the proof all the way back to the source. addressed to the *link id* of the *link*. It contains the following data: The newly generated X25519
public key *LKr* and an RSA-1024 signature of the *link id* and *LKr*.
* | By verifying this *link proof* packet, all nodes that originally transported the *link request*
packet to the destination from the originator can now verify that the intended destination received
the request and accepted it, and that the path they chose for forwarding the request was valid.
In sucessfully carrying out this verification, the transporting nodes marks the link as active.
An abstract bi-directional communication channel has now been established along a path in the network.
* | When the source receives the *proof* , it will know unequivocally that a verified path has been * | When the source receives the *proof* , it will know unequivocally that a verified path has been
established to the destination, and that information can now be exchanged reliably and established to the destination. It can now also use the X25519 public key contained in the
securely. *link proof* to perform it's own Diffie Hellman Key Exchange and derive the symmetric key
that is used to encrypt the channel. Information can now be exchanged reliably and securely.
Its important to note that this methodology ensures that the source of the request does not need to Its important to note that this methodology ensures that the source of the request does not need to
reveal any identifying information. Only the intended destination will know “who called”, so to reveal any identifying information about itself. The link initiator remains completely anonymous.
speak. This is a huge improvement to protocols like IP, where by design, you have to reveal your
own address to communicate with anyone, unless you jump through a lot of hoops to hide it.
Reticulum offers initiator anonymity by design.
When using *links* , Reticulum will automatically verify anything sent over the link, and also When using *links*, Reticulum will automatically verify all data sent over the link, and can also
automates retransmissions if parts of a message was lost along the way. Due to the caching features automate retransmissions if *Resources* are used.
of Reticulum, such a retransmission does not need to travel the entire length of an established path.
If a packet is lost on the 8th hop of a 12 hop path, it can be fetched from the last hop that received it
reliably.
.. _understanding-resources: .. _understanding-resources: