This is the archived Spring 2015 version of the course. For the most recent version, see http://bitcoin-class.org.

# Class 23: Sidechains

Posted: Wed 08 April 2015

## Schedule

Each team will have an opportunity to present their project the last three classes (April 20, 22 and 27). Teams will sign up for presentation slots at Monday's class. Final projects are due by 11:59pm on Sunday, 3 May.

Thursday, 6pm Commerce School 223. Entrepreneurial and Career Ventures in the world of Digital Currency Panel.

Friday, 10:45am Rice 242. Suman Jana, Rise of the Planet of the Apps: Security and Privacy in the Age of Bad Code.

Note: due to a bug in slideshare's updated player, ink markings no longer appear in the viewer.
If you download the slides, they are present though. Hopefully, the player will be fixed someday.

# Bloom Filters

Burton Bloom, Space/Time Trade-offs in Hash Coding with Allowable Errors, Communications of the ACM, July 1970.

### Conventional Hash Table

Store collection of N b-bit elements, using k > N cells.

H is pseudorandom function, H(x) ← [0, k).

### Bloom Filter

Tradeoff: shrink size of array to store, accept false matches.

m = number of bits in array
k = number of hash functions
n = number of elements

What is the probability a given element of the array is not selected by a particular hash function?

What is the probability a given element of the array is not selected for a particular element by any of the k hash functions?

After n elements, what is the probability that an array bit is 0?

Probability of false match: (1 - (1 - 1/m)kn)k

How big should m be to have less than 0.01% false positive rate for a block with 1000 addresses?

How much privacy does using a bloom filter provide to an SPV wallet?

# Merged Mining

Merged Mining Specification

How can Namecoin leverage Bitcoin mining power while maintaining its own blockchain and difficulty level?

What are the advantages of enabing bitcoin miners to also mine namecoin?

# Side Chains

Why is it so hard to evolve bitcoin?

Adam Back, Matt Corallo, Luke Dashjr, Mark Friedenbach, Gregory Maxwell, Andrew Miller, Andrew Poelstra, Jorge Timón, and Pieter Wuille. Enabling Blockchain Innovations with Pegged Sidechains.

Blockstream

# Class 22: Subsidies, Ombuds, Melange

Posted: Mon 06 April 2015

## Schedule

If your group didn't already send me a project progress update, please remember to do so by midnight tonight. Your update should either point to your first deliverable (as specified in your proposal), or explain what progress you've made and issues that have come up. It does not need to be a long or formal report, but enough to see that you're making progress and raise any issues before it is too late to deal with them.

Thursday evening at 6pm in Comm School (RRH) room 223 there will be a bitcoin panel hosted by Carol Van Cleef, and including Alex Kuck, Nick Skelsey, Josh Cincinnati, David Evans, and Denis Nekipelov as panelists. Please fill in this form to make sure they order enough pizza: http://goo.gl/forms/1LJyaR9nCV

## Recap

Subsidy Studies
Laurence Meyers, Jacob Rosenberg

Alex Kuck and Nick Skelsey presented about Ombuds.

Hunter Leath presented about Namecoin and Melange

Next class, we'll talk about sidechains:

Adam Back, Matt Corallo, Luke Dashjr, Mark Friedenbach, Gregory Maxwell, Andrew Miller, Andrew Poelstra, Jorge Timón, and Pieter Wuille. Enabling Blockchain Innovations with Pegged Sidechains.

# Bitcoin Panel

Posted: Wed 01 April 2015

There will be a panel on "Bitcoins and Entrepreneurial and Career Ventures in the world of Digital Currency" next week Thursday, April 9 at 6pm (location to be announced soon).

The Discussion on Bitcoins and Entrepreneurial Ventures in the world of Digital Currency will provide an introduction to the Bitcoin Marketplace, entrepreneurial ventures in the space, and share tips for navigating career opportunities. The session will also provide a forum to discuss the technical, policy, economic related implications associated with Bitcoins and digital currency. Pizza will be provided!

Panelists include:

Carol Van Cleef (Panel Moderator, Attorney - Mannat, Phelps, & Phillips)
Josh Cincinnati (Entrepreneur)
David Evans (Computer Science)
Denis Nekipelov (Economics)
Alex Kuck (student - Bitcoin Entrepreneur)
Nick Skelsey (student - Bitcoin Entrepreneur)

# Class 21: Project Proposal Presentations 2

Posted: Wed 01 April 2015

PointCoin Pizza — Revamped [Slides]
Kyle Angelotti and Michelle Wang

PointList: the PointCoin Marketplace
Anat Gilboa, Benjamin Edgar

Kickstarting PointCoin
Jake Shankman

Studying Coinbase Reserves as a means of Predicting Market Price
Alex Coffin, Ankit Gupta, Tara Raj, Corrigan Blanchfield

Anonymity in Practice
Satoshi Nakamoto

A Decentralized Banking Scheme for Communal Funds
Ori Shimony

Bitcoin Market Price
Oriana Ngo and Avinash Ramesh

Some Interesting Links (Wed 01 April 2015)

Class 20: Project Proposal Presentations 1 (Mon 30 March 2015)

Office Hours Today (Mon 30 March 2015)

Fall 2015 Course (Thu 26 March 2015)

Class 19: Josh Cincinnati Visit (Wed 25 March 2015)

Project Proposal Presentations (Wed 25 March 2015)