The public key can be viewed by everyone and serves as the address for the respective participant. In Bitcoin, the public key is converted to the Bitcoin address by using two algorithms .
The public key is calculated with the formula K= k * G . K is the public key, k the private key and G is a constant point (generator point). The relationship between the private and public key is fixed, but the calculation only works in one direction. Therefore, it is not possible to conclude to the private key by only knowing the public key .
Because the public key is public, it can be used for a digital signature. It is possible for anyone to verify the sender of a message encrypted with the corresponding private key. Thus, trust and security can be generated in a Blockchain without a central control .
 Antonopoulos, A. (2015): Mastering Bitcoin Unlocking Digital Cryptocurrencies
 Heines, R. (2017): Blockchain Technology Applications: A Conceptual Framework from a Supply Chain Perspective