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Fast Curve Crypto Library - TweetNacl in Java

API/Usage

Suggest always use TweetNaclFast implementation

Public key authenticated encryption

  • get key pair: Box.KeyPair kp = Box.keyPair(), kp = Box.keyPair_fromSecretKey(sk)
  • new Box object: Box box = new Box(theirPublicKey, mySecretKey, Nonce);
  • encryption: cipher = box.box(message);
  • decryption: message = box.open(cipher);
  • Nonce MUST be unique for ever message passed between same peers

As an alternative, the nonce can be omitted from the Box() call, and passed in the box and open calls, like:

  • byte [] nonce = new byte[nonceLength], randombytes(theNonce, nonceLength);
  • Box.KeyPair kp = Box.keyPair(), kp = Box.keyPair_fromSecretKey(sk)
  • Box box = new Box(theirPublicKey, mySecretKey);
  • encryption: cipher = box.box(message, nonce);
  • decryption: message = box.open(cipher, nonce);

Secret key authenticated encryption

  • get shared key: crypto random, what you have
  • new SecretBox object: SecretBox sbox = new SecretBox(sharedKey, Nonce);
  • encryption: cipher = sbox.box(message);
  • decryption: message = sbox.open(cipher);
  • Nonce MUST be unique for ever message passed between same peers

As an alternative, the nonce can be omitted from the SecretBox() call, and passed in the box and open calls, like:

  • byte [] nonce = new byte[nonceLength], randombytes(theNonce, nonceLength);
  • SecretBox sbox = new SecretBox(sharedKey);
  • cipher = sbox.box(message, nonce);
  • decryption: message = sbox.open(cipher, nonce);

Signature

  • get key pair: Signature.KeyPair kp = Signature.keyPair(), kp = Signature.keyPair_fromSecretKey(sk);
  • new Signature object: Signature sig = new Signature(theirPublicKey, mySecretKey);
  • sign: signedMessage = sig.sign(message);
  • verify: message = sig.open(signedMessage);
  • Nonce MUST be unique for ever message passed between same peers

Hash

  • generate SHA-512: byte [] tag = Hash.sha512(message);

Refer to com.iwebpp.crypto.tests for details

About Random generation

  • the library uses java.security.SecureRandom for key generation
  • you can always use the library to generate key, or use a Crypto Random like java.security.SecureRandom

Testing

In top directory:

$ mkdir out
$ javac -d out src/com/iwebpp/crypto/*.java src/com/iwebpp/crypto/tests/*.java
$ java -cp out com.iwebpp.crypto.tests.TweetNaclTest
$ java -cp out com.iwebpp.crypto.tests.TweetNaclFastTest

License MIT