Introduction -- An Overview of ADS-B -- Basic Techniques for Securing ADS-B Systems -- Enabling Confidentiality for ADS-B Broadcast Messages -- Efficient ADS-B Broadcast -- Authentication with Batch Verification -- Efficient ADS-B Broadcast Authentication Using IBS-MR -- Practical and Compatible Cryptographic Solution to ADS-B Security -- Enable Aircraft Location Verification for Industrial ADS-B -- Future Research Directions -- Conclusion.