For an explanation on how Signal achieves forward and future secrecy, see https://signal.org/blog/advanced-ratcheting/ https://signal.org/blog/advanced-ratcheti

For an explanation on how Signal achieves forward and future secrecy, see https://signal.org/blog/advanced-ratcheting/ https://signal.org/blog/advanced-ratcheting/ (or https://signal.org/docs/specifications/doubleratchet/ https://signal.org/docs/specifications/doubleratchet/ for something more detailed).