anchor.diff:    /** Decompress a compressed public key (x co-ord and low-bit of y-coord). */
     static ECPoint _decompressKey(BigInteger xBN, bool yBit) {
       // This code is adapted from Bouncy Castle ECCurve.Fp.decodePoint(), but it wasn't easily re-used.
  -    fp.ECCurve curve = EC_CURVE;
  +    fp.ECCurve curve = _EC_CURVE;
       ECFieldElement x = new fp.ECFieldElement(curve.q, xBN);
       ECFieldElement alpha = x * (x.square() + curve.a) + curve.b;
       ECFieldElement beta = alpha.sqrt();
  
positive.code:    */
    String signMessage(String message, [KeyParameter aesKey]) {
      if(_priv == null) 
        throw new Exception("This ECKey does not have the private key necessary for signing.");
      Uint8List data = Utils.formatMessageForSigning(message);
      Sha256Hash hash = new Sha256Hash.doubleDigest(data);
      ECDSASignature sig = sign(hash, aesKey);
  
negative.code:     //        do another iteration of Step 1.
      //
      // More concisely, what these points mean is to use X as a compressed public key.
      fp.ECCurve curve = _EC_CURVE;
  
      BigInteger prime = curve.q;
      // Bouncy Castle is not consistent about the letter it uses for the prime.
  