mCaptcha

CLI tool

A CLI tool exists to compute mCaptcha challenges. It can be installed from multiple sources:

Install

crates.io

The CLI tool is available on, crates.io, the Rust language’s package registry. Rust language toolchain is required to install from crates.io, please see rustup.rs for Instructions to install it.

1cargo install mcaptcha-cli

Pre-compiled binaries

Nightly builds and stable releases are regularly published to dl.mcaptcha.org for a variety of CPU architectures and operating systems.

  1. Download binary, checksum and GPG signature files
1wget https://dl.mcaptcha.org/mcaptcha/cli/{VERSION}/{FILENAME}.tar.gz
2wget https://dl.mcaptcha.org/mcaptcha/cli/{VERSION}/{FILENAME}.tar.gz.asc
3wget https://dl.mcaptcha.org/mcaptcha/cli/{VERSION}/{FILENAME}.tar.gz.sha256
  1. Verify checksum
1sha256sum -c {FILENAME}.tar.gz.sha256
  1. Download mCaptcha’s GPG release keys and verify GPG signature
1gpg --keyserver keyserver.ubuntu.com --recv 73DAC973A9ADBB9ADCB5CDC4595A08135BA9FF73
2gpg --verify {FILENAME}.tar.gz.asc
  1. Install Binary
1tar -xvzf {FILENAME}.tar.gz && sudo cp {FILENAME}/mcaptcha-cli /usr/local/bin

Build from source

  1. Install Rust tool chain Please see here for instructions.
  2. Download source code
1git clone https://git.batsense.net/mCaptcha/cli
  1. Compile and install
1cargo build --release && sudp cp ./target/release/mcaptcha-cli
2/usr/local/bin

Pass mCaptcha challenge

The CLI tool requires details about the challenge to work on it. The tool can be used in three different modes compute challenge:

  1. Protected Page: Compute mCaptcha challenge for the CAPTCHA at a protected page
  2. Widget URL: Compute PoW for captcha at widget URL
  3. (Developer mode) Offline: Computes PoW over given CAPTCHA parameters

From protected page URL

The most convenient mode: copy the URL of the webpage which has the mCaptcha widget (example: showcase.mcaptcha.org) and run the CLI tool with it to get an authorization code: Compute challenge using the URL

103:39 atm@lab cli ±|feat-parse-webpage ✗|→ mcaptcha-cli protected-page https://showcase.mcaptcha.org/
2Authorization token: eRAZJiMrW58uDYA1s64Tmwq1u30HutuF

Widget URL

If you have the widget URL (will be in format https://mcaptcha.example.org/widget?sitekey=randomstring), it can be used to solve challenge as well:

1Compute PoW by fetching parameters from  CAPTCHA URL
2
3Usage: mcaptcha-cli online --url <URL>
4
5Options:
6  -u, --url <URL>  URL of the CAPTCHA. Example:  https://example.org/widget?sitekey=foo
7  -h, --help       Print help

Example usage:

113:32 atm@lab cli ±|online ✗|→ mcaptcha-cli online -u https://demo.mcaptcha.org/widget?sitekey=pHy0AktWyOKuxZDzFfoaewncWecCHo23
2Authorization token: 3xleN26OctBuVu3X4t6CYyUjErhaxQvz

[Developer mode] Offline

Useful while debugging mCaptcha configurations, works on raw challenge parameters.

Help menu:

1Compute PoW with offline parameters
2
3Usage: mcaptcha-cli offline --salt <SALT> --phrase <PHRASE> --difficulty-factor <DIFFICULTY_FACTOR>
4
5Options:
6  -s, --salt <SALT>                            Salt with which PoW should be computed
7  -p, --phrase <PHRASE>                        Phrase over which PoW should be computed
8  -d, --difficulty-factor <DIFFICULTY_FACTOR>  Difficulty Factor
9  -h, --help                                   Print help

Example usage:

113:28 atm@lab cli ±|online|→ mcaptcha-cli offline -s $(rand 32) -p $(rand 32) -d 50000
2difficulty: 50000
3nonce: 90507
4original phrase: f351f333d44b2c6b5bf7f033b065bbb8fb5e9dd153bd402e43ed04425f5a3859
5result: 340276562956196291522979356090220150471

Where rand is this script.

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