tx: use original Keccak256 hash function

Author: volodymyrprokopyuk

.gitignore

@@ -1,3 +1,4 @@
 .keystore*/
 .blockstore*/
 bcn
+coverage.cov

chain/tx.go

@@ -14,9 +14,10 @@ type Hash [32]byte
 
 func NewHash(val any) Hash {
   jval, _ := json.Marshal(val)
-  hash := make([]byte, 64)
-  sha3.ShakeSum256(hash, jval)
-  return Hash(hash[:32])
+  state := sha3.NewLegacyKeccak256()
+  _, _ = state.Write(jval)
+  hash := state.Sum(nil)
+  return Hash(hash)
 }
 
 func (h Hash) String() string {

doc/transaction.org

@@ -127,9 +127,10 @@ type Hash [32]byte
 
 func NewHash(val any) Hash {
   jval, _ := json.Marshal(val)
-  hash := make([]byte, 64)
-  sha3.ShakeSum256(hash, jval)
-  return Hash(hash[:32])
+  state := sha3.NewLegacyKeccak256()
+  _, _ = state.Write(jval)
+  hash := state.Sum(nil)
+  return Hash(hash)
 }
 
 func (h Hash) String() string {