Add basic transaction/block code to Tributary

coordinator/tributary/src/merkle.rs

@@ -0,0 +1,41 @@
+use blake2::{Digest, Blake2s256};
+
+pub(crate) fn merkle(hash_args: &[[u8; 32]]) -> [u8; 32] {
+  let mut hashes = Vec::with_capacity(hash_args.len());
+  for hash in hash_args {
+    hashes.push(Blake2s256::digest([b"leaf_hash".as_ref(), hash].concat()));
+  }
+
+  let zero = [0; 32];
+  let mut interim;
+  while hashes.len() > 1 {
+    interim = Vec::with_capacity(hashes.len() / 2);
+
+    let mut i = 0;
+    while i < hashes.len() {
+      interim.push(Blake2s256::digest(
+        [
+          b"branch_hash".as_ref(),
+          hashes[i].as_ref(),
+          hashes
+            .get(i + i)
+            .map(|hash| {
+              let res: &[u8] = hash.as_ref();
+              res
+            })
+            .unwrap_or(zero.as_ref()),
+        ]
+        .concat(),
+      ));
+      i += 2;
+    }
+
+    hashes = interim;
+  }
+
+  let mut res = zero;
+  if let Some(hash) = hashes.get(0) {
+    res.copy_from_slice(hash.as_ref());
+  }
+  res
+}