Do sidechains solve any real problem not already solved by altcoin exchanges?
Also, I am confused by:
Its important to note however, that it has been suggested that the outright theft of coins by miners may be protected against using zk-SNARKs.(
https://eprint.iacr.org/2013/507.pdf)
I know that zk-SNARKs can resolve transaction verification anonymity issues, providing true security. I've read the zerocash proposals, and am familiar with the mathematical basis. But the information I have seen is that this actually makes 51% attacks easier (because it slows down propagation through the network, wasting node cycles and effectively decreasing the computational power of the network). The link is to one of the original program execution verification papers and is unrelated to cryptocurrency except in the general way that execution verification is the point. So eating newly minted coins is actually not stopped, and I imagine that is the security risk mentioned in passing here.
Is there a new algorithm being mentioned that goes beyond the zerocash proposals here? Does this refer to something else?