user47349: Is there any entity in the blockchain that maintains record and manages public/private key pairs of all the users?

user5757: No, there isn't.  Bitcoin has no central management of anything at all.  
Public keys are pseudonymous and in general it may not be possible to identify the user to whom a public key belongs.  A private key is kept by the user who generated it, and typically is never revealed to anybody else.

47349: <p>Is there any entity in the blockchain that maintains record and manages public/private key pairs of all the users?</p>
 5757: <p>No, there isn't.  Bitcoin has no central management of anything at all.  </p>

<p>Public keys are pseudonymous and in general it may not be possible to identify the user to whom a public key belongs.  A private key is kept by the user who generated it, and typically is never revealed to anybody else.</p>
