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Noah Zinsmeister
Noah Zinsmeister fix security issue
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Client Raindrop


The client-facing implementation of Raindrop is a natural successor to legacy two-factor authentication solutions. Applications like Google Authenticator and Authy rely on access to shared secrets, secrets that are vulnerable to hacks and data breaches. With Client Raindrop, user's secrets never leave their device. And on the backend, we're using the blockchain to eliminate reliance on trusted third parties while ensuring that users will still be able to verify sign-in and other requests with the click of a button.

Contract Address

Client Raindrop is live on the Ethereum mainnet and the Rinkeby testnet.

Technical Note

Unfortunately, message signing in Ethereum is implemented inconsistently across software packages. Our view is that only message hashes should be signed, not raw messages, and that the Ethereum signed message prefix can optionally be appended to the message hash before it's hashed again. Please see the table below for a summary:

Acceptable Message Encoding
"123456" keccak256("123456")
"123456" keccak256("\x19Ethereum Signed Message:\n32", keccak256("123456"))
"123456" keccak256("\x19Ethereum Signed Message:\n6123456")

Notes: Arguments to keccak256 are tightly packed. The output of the above encodings are:


Testing With Truffle

  • This folder has a suite of tests created through Truffle
  • To run these tests:
    • Download the code: git clone
    • Navigate to the raindrop-client folder in your terminal
    • Make sure you have Truffle and Ganache installed: npm install -g truffle@4.1.8 ganache-cli
    • Install web3 and ethereumjs-util: npm install web3@1.0.0-beta.33 ethereumjs-util
    • Spin up a development blockchain: ganache-cli --seed hydro --port 8555
    • Run the test suite: truffle test --network ganache

Copyright & License

Copyright 2018 The Hydrogen Technology Corporation under the GNU General Public License v3.0.

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