 Similarly, user B who intends to communicate with user A is also issued a pair of public and private keys (KpubB and KprivB). Several public-key crypto- graphic techniques are available in the industry and although the underlying mathematics may be dif- ferent, they all share the same principles described here. Once the pair of keys has been generated for a user, the public key can become publicly known without any constraint. It enhances security rather than compromises it. People freely share their pub- lic key with others without any fear. The user's private key, however, must remain private and secret SO that only the user knows it. The robustness and beauty of the concept relies on the premise that the public key of user A or B is known by everyone, whereas the private key of user A or B is only known by user A or B respectively. We deviate for a moment to clarify a concept. Earlier the term issuance was used for these pairs of keys. Public-key cryptography sometimes uses an overriding security officer (for example, at the enterprise level) that issues these keys to legitimate users of an organization. In other well-known cases, such as the famous Pretty Good Privacy (PGP) encryption environment, users generate their own public-private key pairs by clicking a few buttons from a menu-driven software program. We do not concern ourselves here with key management issues that pertain to information security. Key man- agement is a generic term describing all issues related to generating, updating, discarding, recycling, verifying, storing, distributing, and managing cryptographic keys safely and reliably among a group of users in a specific group or community of interests according to applicable organizational policies. It is applicable to both private- and public-key cryptographic contexts, but it requires more work in public-key cryptographic contexts. Let us return to the concept of public-key cryptography. In order for users A and B to securely communicate with each other based on such a method, the following