Quote from: AshCoiner on April 11, 2015, 02:23:14 AM

If you are using a bad/poor client, I suggest you not to reuse addresses. Reusing addresses when using a bad/poor client will put you in danger as it exposes reused R values which will make a person easy to find your private key.

Thank you for your advice, Muhammad. Being new, I'm not quite sure I understand this part of it, though.

Blockchain.info wallet lost ~200(+) Bitcoins because it exposed reused R values. When R values are reused, other persons can use it to find your private key.

Similar example: You use phone and is protected with PIN. When you unlock it many times, some marks may be seen on your phone screen. A person maybe able to find your PIN by looking at the marks. I know it because I have find few PINs of my acquaintances' phones. Grin

P.S. I did it on educational purpose and don't use this trick to unlock others' phones with bad intentions.