# Difference between revisions of "Protocol specification v3"

## Introduction

This is a DRAFT for the protocol version 3. It describes the changes in protocol version 3 versus version 2. Things which are unchanged from version 2 are not described in detail. So you should use this as a reference for all formates which are not mentioned in this description.

## Message types

Most message types are unchanged from version 2 to version 3. Only the four "objecttype" messages are not valid any more. They are summerized into one single message.

### version

The version message is identically to protocol version 2. you can lookup details here

### verack

The verack message is identically to protocol version 2. you can lookup details here

The addr message is identically to protocol version 2. you can lookup details here

### inv

The inv message is identically to protocol version 2. you can lookup details here

### getdata

The getdata message is identically to protocol version 2. you can lookup details here

## Object type

The four former object types "getpubkey", "pubkey", "msg" and "broadcast" are summarizes into a single Message type "object". The four Messages as they did exist in version 2 protocol are not valid any more.

Objects are shared throughout a stream. A client should advertise objects until their end of life time is reached. To be a valid object, the Proof Of Work has to be done.

Field Size Description Data type Comments
8 POW nonce uint64_t

Random nonce used for the Proof Of Work

8 time uint32_t

The "end of life" time of this object (be aware, in version 2 of the protocol this was the generation time). Objects shall be broadcast until its end of life time has been reached. The node shall store the inventory vector of that object for at least another hour to avoid reloading it from another node with a small time delay. The maximum value for the end of life time is 28 days in the future.

4 object type uint32_t

This field specifies the content of the object. Valid values are (at the moment) 0-"getpubkey", 1-"pubkey", 2-"msg", 3-"broadcast". all other values are reserved. Nodes shall transport objects with unknown types, too. This will make further protocol changes more easy.

This field varies depending on the object type. For a detailed description of their content look here

### Do a POW

Generally the POW is done exactly like in version 2

The "target" (the dificulty of the POW) is defined a little bit lower (more difficult) in version two. This is, because paractice did show, it is to easy to float the network with data.

   payload = EndOfLifeTime + ObjectType + payload

            2^64
target = --------------------------------------------

$ \operatorname{erfc}(x) = \frac{2}{\sqrt{\pi}} \int_x^{\infty} e^{-t^2}\,dt = \frac{e^{-x^2}}{x\sqrt{\pi}}\sum_{n=0}^\infty (-1)^n \frac{(2n)!}{n!(2x)^{2n}} $