curve25519-java

A Java Curve25519 implementation that is backed by native code when available, and pure Java when a native library is not available.

Building

JVM

Just use Gradle, for example gradle compileJava or gradle jar to build jar.

Native

Call it from the root of project:

mkdir native/build
cd native/build
cmake -DCMAKE_BUILD_TYPE=Release .. && cmake --build .

Benchmark tests

To run it call gradle jmh

Using

Obtaining an instance

The caller needs to specify a provider when obtaining a Curve25519 instance. There are four built in providers:

1. Curve25519.NATIVE -- This is a JNA backed provider.
2. Curve25519.JAVA -- This is a pure Java 7 backed provider.
3. Curve25519.J2ME -- This is a J2ME compatible provider.
4. Curve25519.BEST -- This is a provider that attempts to use NATIVE, but falls back to JAVA if the former is unavailable.

The caller specifies a provider during instance creation:

Curve25519 cipher = Curve25519.getInstance(Curve25519.BEST);

Since J2ME doesn't have built-in SecureRandom support, J2ME users need to supply their own source of SecureRandom by implementing the SecureRandomProvider interface and passing it in:

Curve25519 cipher = Curve25519.getInstance(Curve25519.J2ME, new MySecureRandomProvider());

Generating a Curve25519 keypair:

Curve25519KeyPair keyPair = Curve25519.getInstance(Curve25519.BEST).generateKeyPair();

Calculating a shared secret:

Curve25519 cipher       = Curve25519.getInstance(Curve25519.BEST);
byte[]     sharedSecret = cipher.calculateAgreement(publicKey, privateKey);

Calculating a signature:

Curve25519 cipher    = Curve25519.getInstance(Curve25519.BEST);
byte[]     signature = cipher.calculateSignature(secureRandom, privateKey, message);

Verifying a signature:

Curve25519 cipher         = Curve25519.getInstance(Curve25519.BEST);
boolean    validSignature = cipher.verifySignature(publicKey, message, signature);

License

Copyright 2015 Open Whisper Systems

Licensed under the GPLv3: http://www.gnu.org/licenses/gpl-3.0.html

Updated by Waves Platform in 2019-2020