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wtf is scrypt-opt?

eternal-flame-ad/scrypt-opt — explained in plain English

Analysis updated 2026-07-22 · repo last pushed 2025-10-17

2RustAudience · developerComplexity · 4/5QuietSetup · moderate

TL;DR

A high-speed implementation of the scrypt password hashing algorithm in Rust, designed to outperform existing tools by using processor features like AVX2 and AVX-512. It is intended for benchmarking and proof-of-work tasks, not for secure password storage.

Mindmap

mindmap
  root((repo))
    What it does
      Fast scrypt hashing
      Overlaps two halves
      AVX2 and AVX512
    Tech stack
      Rust
      AVX2
      AVX512
    Use cases
      Bot deterrent puzzles
      CPU crypto mining
      Password recovery
    Audience
      Benchmarking enthusiasts
      Crypto developers
    Caveats
      Not audited
      Not for production passwords

Code map

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Why would anyone build with this?

REASON 1

Build a website bot deterrent that forces visitors to solve a proof-of-work puzzle before granting access.

REASON 2

Perform CPU-based cryptocurrency mining using optimized scrypt computations.

REASON 3

Benchmark system performance by comparing scrypt hash speed against other tools.

REASON 4

Recover forgotten passwords by testing a file of likely candidates against a scrypt hash.

What's in the stack?

RustAVX2AVX-512

How it stacks up

eternal-flame-ad/scrypt-opt132ikl/game1lystore/pay-dcp
Stars222
LanguageRustRustRust
Last pushed2025-10-172020-12-30
MaintenanceQuietDormant
Setup difficultymoderatemoderatemoderate
Complexity4/52/53/5
Audiencedevelopergeneraldeveloper

Figures from each repo's GitHub metadata at analysis time.

How do you spin it up?

Difficulty · moderate Time to first run · 30min

Requires a modern Intel or AMD processor with AVX2 or AVX-512 support to achieve the intended performance gains.

Wtf does this do

scrypt-opt is a fast implementation of the scrypt password hashing algorithm, written in the Rust programming language. Scrypt is a computationally intensive process designed to be deliberately expensive in terms of both processing power and memory. This project is built to compute those hashes very quickly by taking full advantage of specialized hardware features found in modern computer processors. At its core, the tool works by breaking the scrypt calculation into two halves and running them simultaneously. Normally, scrypt forces a processor to wait around while fetching data from memory. To combat this, the software overlaps two different parts of the math so the processor always has something useful to do while it waits. It also uses specific processor capabilities, like AVX2 and AVX-512 on Intel and AMD chips, to process larger chunks of data at once. The benchmarks show it can outperform established tools like John the Ripper on equivalent hardware. The main users of this project are people building systems that need to prove computational effort. For example, a website could use it as a bot deterrent by forcing a visitor's browser to solve a small puzzle before granting access. It can also be used for CPU-based cryptocurrency mining, system benchmarking, or recovering forgotten passwords from a list of likely candidates. It even includes a command-line demo tool to solve these proof-of-work puzzles and test password recovery on a file of common passwords. One important caveat is that the author explicitly states this is not audited cryptography. Because it has not undergone formal security review, it is not recommended for safely storing real user passwords in a production database. It is built for speed in competitive or benchmarking scenarios rather than safeguarding sensitive data.

Yoink these prompts

Prompt 1
Help me build a bot-deterrent system using scrypt-opt where a visitor's browser must solve a proof-of-work puzzle before accessing a webpage. Walk me through the setup.
Prompt 2
I want to benchmark scrypt-opt against John the Ripper on my machine. Help me write a script that runs both tools and compares their scrypt hashing speeds.
Prompt 3
Guide me through using the scrypt-opt command-line demo tool to test password recovery on a file of common passwords against a target hash.
Prompt 4
Explain how scrypt-opt overlaps the two halves of the scrypt calculation to keep the processor busy while waiting for memory fetches, and how I can apply a similar pipelining technique to my own Rust code.

Frequently asked questions

wtf is scrypt-opt?

A high-speed implementation of the scrypt password hashing algorithm in Rust, designed to outperform existing tools by using processor features like AVX2 and AVX-512. It is intended for benchmarking and proof-of-work tasks, not for secure password storage.

What language is scrypt-opt written in?

Mainly Rust. The stack also includes Rust, AVX2, AVX-512.

Is scrypt-opt actively maintained?

Quiet — no commits in 6-12 months (last push 2025-10-17).

How hard is scrypt-opt to set up?

Setup difficulty is rated moderate, with roughly 30min to a first successful run.

Who is scrypt-opt for?

Mainly developer.

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