Here, we need a method of generating the address that has a close relationship with the digital signature, which is the information about the owner. In a public key cryptography system, just as the private key is the information required for a digital signature, the address is also information derived from the private key. The address is the hash value of the public key used when verifying the private key, as shown in the figure below. From the point of view of recipient B, in order to transfer the amount received from A to another person, the fund must first be delivered to address B. And then, recipient B must digitally sign a transaction using his private key to prove that he is the owner of this address.