CKey: add method to negate the key

src/key.cpp

@@ -163,6 +163,12 @@ void CKey::MakeNewKey(bool fCompressedIn) {
     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;

src/key.h

@@ -98,6 +98,9 @@ public:
     //! 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).
      * This is expensive.