Project Overview

This project explores the implementation and optimization of the SHA-256 cryptographic hash function and its application in Bitcoin hashing using SystemVerilog.

Table of Contents

• Project Overview
• SHA-256 Overview
• Bitcoin Hashing Overview
• Implementation Details
  • SHA-256 Algorithm
  • Bitcoin Hashing Algorithm
• Optimizations
• Snapshots and Reports
• Resource Usage and Performance

SHA-256 Overview

SHA-256 (Secure Hash Algorithm 256-bit) is a cryptographic hash function widely used in security applications and blockchain technology.

Key features:

• Compression: Produces fixed-length 256-bit hashes regardless of input size.
• Avalanche Effect: Small input changes yield large output changes.
• Deterministic: Identical inputs produce identical outputs.
• Preimage Resistant: The original input cannot be deduced from the hash.
• Collision Resistant: Difficult for two inputs to result in the same hash.

Bitcoin Hashing Overview

Bitcoin mining leverages SHA-256 to solve cryptographic puzzles by finding a hash meeting specific criteria, such as starting with a specified number of zeros. The process involves:

• Appending a nonce to input data.
• Iteratively hashing until a valid hash is found.

Implementation Details

SHA-256 Algorithm

• Input: Divided into 512-bit blocks.
• Processing: Each block undergoes 64 rounds of compression using pre-defined constants and message expansion.
• Output: A final 256-bit hash.

SystemVerilog Implementation

• Finite State Machine (FSM):
  • States include IDLE, WAIT, READ, BLOCK, COMPUTE, WRITE, and INCREMENT.
• Key Functions:
  • sha256_op: Performs a single round of compression.
  • wtnew: Computes expanded message words.
  • Optimized Memory Usage: Reduced from 64 to 16 memory units for expanded words.

Bitcoin Hashing Algorithm

• Parallel SHA-256 Modules:
  • Multiple modules instantiated using a generate loop for nonce-based parallel processing.
• FSM: Handles transitions across states for reading, hashing, and writing results.
• Three-Phase Hashing:
  • Phase 1: Initial block hashing.
  • Phase 2: Second block preparation and hashing.
  • Phase 3: Third block hashing and final output.

Optimizations

1. SHA-256 Optimization:
   • Reduced word memory requirements for message expansion, cutting cycles from ~4000 to 175. This optimization provides a speedup of 22 times.
2. Bitcoin Hashing Optimization:
   • Parallelization of 16 SHA-256 modules, significantly accelerating nonce exploration.

Snapshots and Reports

SHA-256

• Waveforms and Transcript

• FMax Report

• Resource Usage

Bitcoin Hashing

• Waveforms and Transcript

• FMax Report

• Resource Usage

Resource Usage and Performance

• SHA-256: Optimized to minimize memory usage and computational cycles.

• Bitcoin Hasher: Parallelized modules and optimized FSM, reducing the hashing process to minimal cycles.