I was wondering about, how a paper wallet works and found a shocking reality that javascript-based generators can be used to create paper wallet addresses. My question is: is it possible to guess the private keys of the BTC paper wallet? is there any clue in the public key to guess the private key?
For just knowledge purpose, I have created two paper wallets by using the same website
btc-paper-wallet.com twice in one minute. The first letters of both wallet's private keys were the same. You can see this in the screenshot below.
I'm confused about the storage of my BTC that I'm going to buy from coinbase. Should I use a paper wallet? is it still safe? Can people or machines guess my private keys?