JavaScriptNrs

Curve 25519 JavaScript Implementation

Curve25519 is an elliptic curve, developed by Dan Bernstein, for fast Diffie-Hellman key agreement.

• 2006/08/24 C implementation based on generic 64-bit integer implementation of Curve25519 ECDH Written by Matthijs van Duin (http://cds.xs4all.nl:8081/ecdh/) (broken link)
• 2008/02/23 Ported from C to Java by Dmitry Skiba (http://code.google.com/p/curve25519-java/)

This implementation is a port of the Java code and the inclusion of fast 64-bit JavaScript math based on curve255js. It is optimized for Chrome and uses newer JavaScript features like typed arrays. It is not likely to run in older browsers.

Crypto Implementation

A wrapper around the Curve25519 implementation that uses SHA256 hashing. JSSHA256 is used for SHA256 operations. The crypto implementation supports:

• Public key generation
• Signing
• Signature verification

All inputs and outputs are expected to be hex strings.

Examples

    var message = '54686973206973206120736563726574206d6573736167652074686174206e6565647320746f206265207369676e6564';
    var secretPhrase = '54686973206973206d7920766572792073656372657420706872617365';

    var publicKey = nxtCrypto.getPublicKey(secretPhrase);
    console.log(publicKey); // 698168d8669c9310d68101dfcc974ed4
                            // ef454692da6f028f68114db5fdcc4f6a

    var signature = nxtCrypto.sign(message, secretPhrase);
    console.log(signature); // 94956bf3de7cfdedb2562a0eff698fed
                            // 7f3e54bbf4476fbb23a192ddea04040f
                            // 68efa5d03c3f9ebec4109401b50433f1
                            // df267299d8b1ad2c485046c45e6b38da

    var isVerified = nxtCrypto.verify(signature, message, publicKey)
    console.log(isVerified); // true

Project Layout

The main project files are stored in the core directory. A build script is provided that concatenates all of the core files and external dependencies into a single JavaScript file (crypto_browser.js). This is the only file that needs be included from within an HTML page.

bash build/build.sh

A full suite of tests are provided that can be run in node.js.

node test.js

In addition, the browser_test folder contains timing tests that can be run in the browser by opening the html file. In order to run the tests with a different implementation, the following should be changed to refer to the other implementation:

    var c = {
        getPublicKey: nxtCrypto.getPublicKey,
        sign: nxtCrypto.sign,
        verify: nxtCrypto.verify
    };

License Information for External Code

• curve25519-java: Apache License 2.0
• JSSHA256: GNU GPL
• curve255js: MIT