Half-fast A Bitcoin Miner for the FPGA Overview Objectives and - - PowerPoint PPT Presentation

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Half-fast A Bitcoin Miner for the FPGA Overview Objectives and - - PowerPoint PPT Presentation

Sep 08, 2022 19 likes •229 views

Half-fast A Bitcoin Miner for the FPGA Overview Objectives and Motivation Bitcoin System Overview Hardware Software Challenges and Difficulties Lessons learned Objectives and Motivation Build a Bitcoin

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SLIDE 1

Half-fast

A Bitcoin Miner for the FPGA

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SLIDE 2

Overview

  • Objectives and Motivation
  • Bitcoin
  • System Overview
  • Hardware
  • Software
  • Challenges and Difficulties
  • Lessons learned
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SLIDE 3

Objectives and Motivation

  • Build a Bitcoin miner on a FPGA board
  • Mine block data from Bitcoin Network
  • Parallelization
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SLIDE 4

Bitcoin

  • Bitcoin is an open source payment system

based extensively on cryptographic hash functions

  • Mining solves the problem of double

spending through verifying transactions

  • Transactions are public, but have no

personal information

  • Proof-of-work and mining pool
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SLIDE 5

Proof-of-work

  • Based on SHA-256
  • Must find a number which added to a hashed

header will fit a certain number of zeros (difficulty) by incrementing a number called the nonce

  • Hashes change drastically with a tiny

modification, turning it into a very complex problem

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SLIDE 6

Mining pool

The mining pool is a process where multiple clients contribute to the solving of a block and share the rewards Work is organized by leader. Block data is sent to miners to attempt to solve

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SLIDE 7

Mining Algorithm

B = Block of Transactions D = Difficulty (part of B) 1) Construct/Modify B 2) If SHA256(SHA256(B, nonce)) < D End 3) nonce++; Goto 1

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SLIDE 8

SHA256 Algorithm

Message input M Divide M into 512-bit chunks, pad if necessary For each chunk Mi Compression(Mi) //bitwise shifting and rotation Accumulate into registers h0, h1, … h7 hash = {h0, h1, h2, …, h7}

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SLIDE 9

System overview

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SLIDE 10

System overview

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SLIDE 11

Hardware implementation

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SLIDE 12

FSM

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SLIDE 13

Memory Map Interface

input: clk reset write read chipselect writedata[7:0] address[7:0]

  • utput:

readdata[7:0]

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SLIDE 14

Miner Top

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SLIDE 15

FPGA Miner*

*Used an Open Source Miner. Modified it for our interface https://github.com/gardintrapp/Open-Source-FPGA-Bitcoin-Miner

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SLIDE 16

SHA256

e0, e1, ch, maj, s0, s1 - bitwise

  • perations

LOOP parameter determines how many “digester” blocks are instantiated Big LOOP = less space, slower Small LOOP = more space, faster K is array of constant values This is the Compression function unrolled

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SLIDE 17

Software implementation

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SLIDE 18

getwork.c

  • Userspace program written to facilitate communication

between Mining pool and our FPGA miner

  • Creates a getwork request to mining pool
  • Sends the work down to the hardware with IOCTL calls

defined in modified vga_led.c/h

  • Separate threads reads and listens for solved work from

fpga and new work from the mining pool

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SLIDE 19

Challenges and difficulties

  • Debugging hardware logic
  • Writing scalable Verilog code
  • Bookkeeping data and Simulating
  • Learning the Bitcoin system
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SLIDE 20

Lessons learned

  • Be more thorough with initial planning/design process
  • Simulate/Test carefully and thoroughly at each step of

hardware implementation (ModelSim and System Console). Use scripts

  • Start from Lab3 skeleton code
  • Work on hardware and software in parallel
  • Begin hardware software integration as early in

development as possible

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SLIDE 21

Half-fast: a Bitcoin miner for the FPGA

Thank you!