Migrate to blake2b_simd and blake2s_simd crates

The primary reason for migrating is that these crates provide APIs for
setting the personalisation string. This enables us to depend solely on
published crates, and thus publish our own crates.

The SIMD implementations are ported from libsodium.

Closes #67.

zcash_proofs/Cargo.toml

@@ -7,12 +7,9 @@ authors = [
 
 [dependencies]
 bellman = { path = "../bellman" }
+blake2b_simd = "0.5"
 byteorder = "1"
 ff = { path = "../ff" }
 pairing = { path = "../pairing" }
 rand = "0.4"
 sapling-crypto = { path = "../sapling-crypto" }
-
-[dependencies.blake2-rfc]
-git = "https://github.com/gtank/blake2-rfc"
-rev = "7a5b5fc99ae483a0043db7547fb79a6fa44b88a9"

zcash_proofs/src/hashreader.rs

@@ -1,10 +1,10 @@
-use blake2_rfc::blake2b::Blake2b;
+use blake2b_simd::State;
 use std::io::{self, Read};
 
 /// Abstraction over a reader which hashes the data being read.
 pub struct HashReader<R: Read> {
     reader: R,
-    hasher: Blake2b,
+    hasher: State,
 }
 
 impl<R: Read> HashReader<R> {
@@ -12,7 +12,7 @@ impl<R: Read> HashReader<R> {
     pub fn new(reader: R) -> Self {
         HashReader {
             reader: reader,
-            hasher: Blake2b::new(64),
+            hasher: State::new(),
         }
     }
 

zcash_proofs/src/lib.rs

@@ -1,5 +1,5 @@
 extern crate bellman;
-extern crate blake2_rfc;
+extern crate blake2b_simd;
 extern crate byteorder;
 extern crate ff;
 extern crate pairing;