To what extent does asymmetric cryptography secure bitcoin transactions? Is there a specific attack or bug which asymmetric cryptography prevents during bitcoin transactions?
Is there a specific attack or bug which asymmetric cryptography prevents during bitcoin transactions?


asymmetric cryptography is not really something that was added on top of Bitcoin in order to prevent some specific attack or fix some specific bug.

asymmetric cryptography is one of two fundamental foundation stones, one of the two primary building blocks on which the Bitcoin concept is based. Without asymmetric cryptography and one-way hash-functions the whole idea of Bitcoin would not have got started at all.

asymmetric cryptography underlies almost everything that is important in Bitcoin. Without asymmetric cryptography there could be no Bitcoin.

If I had to identify one thing that asymmetric cryptography provides it is that it prevents 7 billion other people being able to remove money from your wallet whenever they want and you being powerless to stop them. Its the difference between putting your cash in a safe only you know the combination for and leaving your cash on a park bench in the center of a crowded city while you go elsewhere for a year.

You might enjoy watching the two videos at https://anders.com/blockchain/ (watch both and in the right order) They are very easy to follow and reasonably brief. The first sets the scene, the second builds on that to answer your question (but you have to watch the first before the second)