diff --git a/src/key.h b/src/key.h
--- a/src/key.h
+++ b/src/key.h
@@ -95,6 +95,9 @@
     //! Generate a new private key using a cryptographic PRNG.
     void MakeNewKey(bool fCompressed);
 
+    //! Negate private key
+    bool Negate();
+
     /**
      * Convert the private key to a CPrivKey (serialized OpenSSL private key
      * data).
diff --git a/src/key.cpp b/src/key.cpp
--- a/src/key.cpp
+++ b/src/key.cpp
@@ -188,6 +188,11 @@
     fCompressed = fCompressedIn;
 }
 
+bool CKey::Negate() {
+    assert(fValid);
+    return secp256k1_ec_privkey_negate(secp256k1_context_sign, keydata.data());
+}
+
 CPrivKey CKey::GetPrivKey() const {
     assert(fValid);
     CPrivKey privkey;