Please never ever ever implement a Merkle tree as you did in https://github.com/jbenet/random-ideas/issues/20 https://github.com/jbenet/random-ideas/issues/20 .

Please never ever ever implement a Merkle tree as you did in https://github.com/jbenet/random-ideas/issues/20 https://github.com/jbenet/random-ideas/issues/20 . This is vulnerable to the same trivial collision attack as the original Gnutella THEX proposal. EDIT: also, please implement non-power-of-2 leaf node Merkle trees as power-of-2 lead node trees with the rightmost leaves containing the hashes of the zero length array, that way the final block along with its hash chain to the root provides a cryptographic proof of file length. This prevents denial-of-service mischief where a malicious server claims a given resource is terabytes large and a poorly written client starts allocating TB of disk space on a filesystem that doesn't support sparse files.