Solidity DKIM

A Solidity library to verify DKIM signatures:

Support rsa-sha1 and rsa-sha256 signature algorithms
Implement both canonicalization algorithms (simple, relaxed)
Support the signature schemes by Gmail, Yahoo, ProtonMail, Outlook
Gas cost under 3 million gas

The contract receive raw email as input and return number of success verifications along with the last success domain or the last fail status (if there's no success).

Getting Started

Clone and install dependencies

$ git clone https://github.com/bakaoh/solidity-dkim
$ cd solidity-dkim
$ npm install

Start ganache

Download email from your inbox

Test with raw email

$ RAW_EMAIL=<path to your email file> npm run test
# example
$ RAW_EMAIL=test/data/gmail-raw.txt npm run test

3rd party Smart Contracts

Troubleshoot

no header boundary found: The raw email must be in "network normal" format (text is ASCII encoded, lines are separated with CRLF characters, etc.). The downloaded files should work just fine, but if you copy the email content to your text editor, you may need to replace \n with \r\n, e.g. input = input.replace(new RegExp("\n", 'g'), "\r\n")

dns query error: The library is using hardcode _domainkey records and your email domain is not in the current list. In the future, we'll need a proper oracle that can read the _domainkey record for any arbitrary domain.