How to improve any of blockchain's privacy issue?

Can u give me any idea about how to work on the privacy issue of blockchain?? .. I mean can u give a direction on which I should research and work regarding privacy issue of blockchain?? my FYP supervisor asked me to research on blockchain privacy issues ..but I don't find a direction .. my supervisor basically wants me to give a better solution to any of privacy issue of blockchain..can u guide me .plz

Could you tell us a bit more about the privacy issue with block-chain? As far as I know, blockchain's main advantage is it helps prevent privacy. You should talk to your supervisor and ask them for more information. 

Do a search and let us know if you find any issues so that we can make suggestions. 

As we know its very secure way for transaction hacker cannot hack.. But if any person who's money is already black and if he transact the money from blockchain technology.. How can all block will be break so that ..we can get that black money back .. Also there is no undo if unfortunately any transaction is done .. There  is no 3rd parties so how the person can undo??

... AFAIK, you'll need to transact online to buy cryptocurrency. I think it's impossible to buy bitcoins or other cryptocurrency using black money. 

Okay..so what will you suggest me to work .. Bcz I am really confused.. I don't find a direction on which I should work regarding blockchain issues

@Zamin If you have been asked to do research, the best way forward is to make yourself equipped with the Blockchain technology. Once you understand the A to Z of the exisitng technology, only then can you come up with better privacy solutions.

I suggest you do a short online course on Blockchain first. Once you do that, go through these new research papers and see what solutions people have proposed for privacy. This way, you will know what better solution you can offer through your project.

Research Papers:

1. Blockchain Access Privacy: Challenges and Directions (Purdue University) . https://www.cs.purdue.edu/homes/akate/publications/BlockchainAccessPrivacy_preprint.pdf
2. Decentralizing Privacy: Using Blockchain to Protect Personal Data (MIT Media Lab and Tel Aviv University)  https://enigma.co/ZNP15.pdf
3. Blockchain Technologies for the Internet of Things: Research Issues and Challenges (IEEE) https://arxiv.org/pdf/1806.09099.pdf
4. Blockchain: Solving the privacy and research availability tradeoff for EHR data: A new disruptive technology in health data management https://ieeexplore.ieee.org/document/8263269

Hope this helps.

Thank u so much <3