Posts about ‘Security’

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Warren GuyWarren Guy
22 June 2015

Deploy a Tor hidden service to Heroku in under a minute

Getting a Tor hidden service running doesn't have to be hard. I've just published an example Sinatra application demonstrating how to deploy a hidden service to Heroku (or Dokku, etc) in just a few lines. The app uses my ruby-hidden-service library with the multi and apt Heroku buildpacks to install and configure Tor. A deployed example is running at

Here are the complete steps required to deploy the sample app:

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Warren GuyWarren Guy
14 October 2014

Regenerating an RSA private key with Python

This is an exercise in regenerating an RSA private key while possessing only the public key. You might also find this useful if you happen to know all of the parameters of a private key (modulus, public exponent, and either the private exponent or prime factors), and want to reconstruct a key from them (skip to the end). This covers only the practical steps required without detailed explanation.

The example used here is a 256-bit RSA key, which can be factored on my laptop in less than three minutes. You won't (I hope) find any 256-bit RSA keys in the real world, however you could likely factor a 512-bit key (which sadly do exist in the wild) with modern hardware in a matter of days.

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