Another very interesting design by an anonymous author is https://scalingbitcoin.org/papers/mimblewimble.txt https://scalingbitcoin.org/papers/mimblewimble.txt

Another very interesting design by an anonymous author is https://scalingbitcoin.org/papers/mimblewimble.txt https://scalingbitcoin.org/papers/mimblewimble.txt where outputs are simply Pedersen commitments r*G+v*H, and ownership is knowledge of their blinding factor r. This require an interaction between sender and receiver to jointly construct a signature, but allows all spent outputs to be completely removed from blockchain history.