BIP 0015

Work In Progress

  BIP: 15
  Title: BIP Alias
  Author: Amir Taaki <genjix@riseup.net>
  Status: Draft
  Type: Standards Track
  Created: 10-12-2011

Using vanilla bitcoin, to send funds to a destination, an address in the form 1Hd44nkJfNAcPJeZyrGC5sKJS1TzgmCTjjZ is needed. The problem with using addresses is they are not easy to remember. An analogy can be thought if one were required to enter the IP address of their favourite websites if domain names did not exist.

This document aims to layout through careful argument, a bitcoin alias system. This is a big modification to the protocol that is not easily changed in the future and has big ramifications. There is impetus in getting it correct the first time. Aliases have to be robust and secure.

Schemes

Here are a few different proposals and the properties of each system.

FirstBits

FirstBits is a proposal for using the blockchain as an address book.

When bitcoins are sent to an address, that address becomes recorded in the blockchain. It is therefore known that this address exists or did exist by simply seeing that there was a payment to that address. FirstBits is a method to have a memorable alias. One first converts the address to lower-case, then takes the first few unique characters. This is your FirstBits alias.

As an example, brmlab hackerspace in Prague has an address for purchasing food or drink, or making donations:

 1BRMLAB7nryYgFGrG8x9SYaokb8r2ZwAsX

Their FirstBits alias becomes:

 1brmlab

It is enough information to be given the FirstBits alias 1brmlab. When someone wishes to make a purchase, without FirstBits, they either have to type out their address laboriously by hand, scan their QR code (which requires a mobile handset that this author does not own) or find their address on the internet to copy and paste into the client to send bitcoins. FirstBits alleviates this impracticality by providing an easy method to make payments.

Together with Vanitygen (vanity generator), it becomes possible to create memorable unique named addresses. Addresses that are meaningful, rather than an odd assemblage of letters and numbers but add context to the destination.

However FirstBits has its own problems. One is that the possible aliases one is able to generate is limited by the available computing power available. It may not be feasible to generate a complete or precise alias that is wanted- only approximates may be possible. It is also computationally resource intensive which means a large expenditure of power for generating unique aliases in the future, and may not scale up to the level of individuals at home or participants with hand-held devices in an environment of ubiquitous computing.

FirstBits scales extremely poorly as the network grows. Each indexer or lookup node needs to keep track of every bitcoin address ever in existence and provide a fast lookup from the aliases to those addresses. As the network grows linearly, the number of addresses should grow exponentially (assuming a networked effect of n!) rapidly making this scheme unfeasible.

Light clients of the partial merkle root types become dependent on a trusted third party for their alias lookups. The cost of storing every bitcoin address is too high considering their typical use-case on low-resource devices. This factor more than the others, means this scheme is sub-optimal and must be rejected.