Resumen
From email to cellular communications, from secure Web access to digital cash, cryptography is an essential part of today's information systems. Cryptography helps provide accountability, fairness, accuracy, and confidentiality. It can prevent fraud in electronic commerce and assure the validity of financial transactions. It can protect one's anonymity or prove one's identity. It can keep vandals from altering the Web page and prevent industrial competitors from reading the confidential documents. And in the future, as commerce and communications continue to move to computer networks, cryptography will become more and more vital. But the cryptography now on the market doesn't provide the level of security it advertises. Most systems are designed and implemented not by cryptographers, but by engineers who think cryptography is like any other computer technology. One can't make systems secure by taking on cryptography as an afterthought. One has to know what one is doing every step of the way, from conception through installation.