jbranca

JBranca is a Java library to create Branca tokens. Branca tokens are an improvement on the no longer maintained Fernet token.

What is a Branca Token?

Branca is a secure easy to use token format which makes it hard to shoot yourself in the foot. It uses IETF XChaCha20-Poly1305 AEAD symmetric encryption to create encrypted and tamperproof tokens. Payload itself is an arbitrary sequence of bytes. You can use for example a JSON object, plain text string or even binary data serialized by MessagePack or Protocol Buffers.

Token Structure

Version (1B) || Timestamp (4B) || Nonce (24B) || Ciphertext (*B) || Tag (16B)

Why?

• Secure
• Easy to implement
• Small token size

What about JWTs?

Since a Branca token is an authenticated and encrypted wrapper around an arbitrary payload you could make a JWT the payload and benefit from not having to worry about JOSE and the small token size. You could decrease the token size even further by using Protocol Buffers or Message Pack for your payload.

Example

    byte[] key = new byte[32];
    new Random().nextBytes(key);
    
    BrancaTokenFactory factory = new BrancaTokenFactory(key);
    String plaintext = "{\"imajwt\": \"imajwt\"}";
    byte[] encoded = factory.seal(plaintext.getBytes());
    byte[] decoded = factory.open(encoded);
    Assert.assertEquals(plaintext, new String(decoded));

Spec

https://github.com/tuupola/branca-spec

Encryption Library: Bouncycastle