Work is stalled on some other library work (to give better lifetime
requirements on `eventual::Future` and avoid some unsafety), so
committing here.
There are only three errors left in this round :)
Also all the indenting is done, so there should be no more massive
rewrite commits. Depending how invasive the lifetime-error fixes
are, I may even be able to do sanely sized commits from here on.
Looks like to implement the crypto opcodes I may need to switch from
rust-crypto to rust-openssl.. or implement RIPEMD-160 for rust-crypto.
In either case I will need to generalize the hash.rs stuff to support
other hashes, so I'm committing here as a checkpoint before doing all
that.
I noticed that the little/big endian hex string functions for Sha256dHash
did not match my intuition. What we should have is that the raw bytes
correspond to a little-endian representation (since we convert to Uint256
by transmuting, and Uint256's have little-endian representation) while
the reversed raw bytes are big-endian.
This means that the output from `sha256sum` is "little-endian", while the
standard "zeros on the left" output from bitcoind is "big-endian". This
is correct since we think of blockhashes as being "below the target" when
they have lots of zeros on the left, and we also notice that when hashing
Bitcoin objects with sha256sum that the output hashes are always reversed.
These two functions le_hex_string and be_hex_string should really not be
used outside of the library; the Encodable trait should give access to a
"big endian" representation while ConsensusEncodable gives access to a
"little endian" representation. That way we describe the split in terms
of user-facing/consensus code rather than big/little endian code, which
is a better way of thinking about it. After all, a hash is a collection
of bytes, not a number --- it doesn't have an intrinsic endianness.
Oh, and by the way, to compute a sha256d hash from sha256sum, you do
echo -n 'data' | sha256sum | xxd -r -p | sha256dsum
This is a massive simplification, fixes a couple endianness bugs (though
not all of them I don't think), should give a speedup, gets rid of the
`serialize_iter` crap.
We were conflicting with the Rust stdlib trait Hash, which is used
by various datastructures which need a general hash. Also implement
Hash for Sha256dHash so that we can use bitcoin hashes as keys for
such data structures.
Andrew Poelstra