Add msgpack wire protocol with halfsiphash checksums

lib/halfsiphash/halfsiphash_test.go

@@ -0,0 +1,31 @@
+package halfsiphash
+
+import "testing"
+
+// Test vectors from the reference implementation.
+// Key: 00 01 02 03 04 05 06 07
+// Input: sequence 00, 00 01, 00 01 02, ...
+var vectors32 = []uint32{
+	0x5b9f35a9,
+	0xb85a4727,
+	0x03a662fa,
+	0x04e7fe8a,
+	0x89466e2a,
+	0x69b6fac5,
+	0x23fc6358,
+	0xc563cf8b,
+}
+
+func TestSum32(t *testing.T) {
+	key := [8]byte{0, 1, 2, 3, 4, 5, 6, 7}
+	for i, want := range vectors32 {
+		data := make([]byte, i)
+		for j := range data {
+			data[j] = byte(j)
+		}
+		got := Sum32(data, key)
+		if got != want {
+			t.Errorf("Sum32(len=%d) = %08x, want %08x", i, got, want)
+		}
+	}
+}