Cryptography, or cryptology, is the practice and study of for secure communication in the presence of adversarial behavior.

More generally, cryptography is about constructing and analyzing protocols that prevent third parties or the from reading private messages; various aspects of information , such as  confidentiality,  integrity, authentication, and non-repudiation, are central to modern cryptography.

Modern cryptography exists at the intersection of the disciplines of  engineering, communication , and . Applications of cryptography include electronic , chip-based payment cards,  currencies,  passwords, and  .

Prior to the current era, cryptography was virtually synonymous with encryption, turning information from legible to nonsensical gibberish.

To prevent attackers from gaining access to an encrypted communication, the sender only discloses the decoding process to the intended receivers.

In the literature on cryptography, the names Alice (“A”) for the sender, Bob (“B”) for the intended , and Eve (“eavesdropper”) for the adversary are used. Since the invention of rotor cipher machines in World I and the introduction of computers in World II, cryptography technologies have grown more complicated and diverse in their uses.

Modern cryptography is heavily based on mathematical and practice;  algorithms are designed around computational hardness assumptions, making such algorithms hard to break in actual practice by any adversary.

While it is theoretically possible to break into a well-designed , it is impossible in actual practice to do so. Such schemes, if well designed, are therefore termed “computationally secure”.

advances, e.g., improvements in  factorization algorithms, and faster require these designs to be continually reevaluated and, if necessary, adapted.

There exist information-theoretically secure schemes that provably cannot be broken even with unlimited power, such as the one-time pad, but these schemes are much more difficult to use in practice than the best theoretically breakable but computationally secure schemes.

Modern cryptography is mainly reliant on mathematical and practice; methods are developed around computational hardness assumptions, making such systems difficult for any adversary to crack in actual practice.

While it is theoretically conceivable to break into a well-designed , doing so in practice is impossible.

Such systems, if correctly constructed, are therefore referred to as “computationally safe.”

breakthroughs, such as improvements in factorization and faster power, necessitate that these designs be reevaluated and, if required, updated on a regular basis.

There are information-theoretically secure that can be proven.

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