If you're interested in using the X3DH handshake that Signal specified, I ported a slight variant of it (which uses libsodium) in TypeScript not too long ago:

If you're interested in using the X3DH handshake that Signal specified, I ported a slight variant of it (which uses libsodium) in TypeScript not too long ago: https://github.com/soatok/rawr-x3dh https://github.com/soatok/rawr-x3dh There's no low-level crypto code here, just high-level protocol stitching. This is still something you'd want to hire experts to review if you built it in Java, of course.