@Override
  public EciesPublicKey getPublicKey() {
    return publicKey;
  }
Creates a new ECIES private key using NIST Curves.

@param publicKey Corresponding ECIES public key for this private key
@param nistPrivateKeyValue private big integer value in bigendian representation
java_src/src/main/java/com/google/crypto/tink/hybrid/EciesPrivateKey.java