diff --git a/src/blockencodings.h b/src/blockencodings.h
--- a/src/blockencodings.h
+++ b/src/blockencodings.h
@@ -27,6 +27,29 @@
     }
 };
 
+class DifferenceFormatter {
+    uint64_t m_shift = 0;
+
+public:
+    template <typename Stream, typename I> void Ser(Stream &s, I v) {
+        if (v < m_shift || v >= std::numeric_limits<uint64_t>::max()) {
+            throw std::ios_base::failure("differential value overflow");
+        }
+        WriteCompactSize(s, v - m_shift);
+        m_shift = uint64_t(v) + 1;
+    }
+    template <typename Stream, typename I> void Unser(Stream &s, I &v) {
+        uint64_t n = ReadCompactSize(s);
+        m_shift += n;
+        if (m_shift < n || m_shift >= std::numeric_limits<uint64_t>::max() ||
+            m_shift < std::numeric_limits<I>::min() ||
+            m_shift > std::numeric_limits<I>::max()) {
+            throw std::ios_base::failure("differential value overflow");
+        }
+        v = I(m_shift++);
+    }
+};
+
 class BlockTransactionsRequest {
 public:
     // A BlockTransactionsRequest message