Nowadays, the networks have gone global and information has taken the digital form of bits and bytes. Critical information now gets stored, processed and transmitted in digital form on computer systems and open communication channels.

Since information plays such a vital role, adversaries are targeting the computer systems and open communication channels to either steal the sensitive information or to disrupt the critical information system.

Modern cryptography provides a robust set of techniques to ensure that the malevolent intentions of the adversary are thwarted while ensuring the legitimate users get access to information. Here in this chapter, we will discuss the benefits that we draw from cryptography, its limitations, as well as the future of cryptography.

## Cryptography – Benefits

Cryptography is an essential information security tool. It provides the four most basic services of information security −

**Confidentiality**− Encryption technique can guard the information and communication from unauthorized revelation and access of information.**Authentication**− The cryptographic techniques such as MAC and digital signatures can protect information against spoofing and forgeries.**Data Integrity**− The cryptographic hash functions are playing vital role in assuring the users about the data integrity.**Non-repudiation**− The digital signature provides the non-repudiation service to guard against the dispute that may arise due to denial of passing message by the sender.

All these fundamental services offered by cryptography has enabled the conduct of business over the networks using the computer systems in extremely efficient and effective manner.

## Cryptography – Drawbacks

Apart from the four fundamental elements of information security, there are other issues that affect the effective use of information −

A strongly encrypted, authentic, and digitally signed information can be

**difficult to access even for a legitimate user**at a crucial time of decision-making. The network or the computer system can be attacked and rendered non-functional by an intruder.**High availability,**one of the fundamental aspects of information security, cannot be ensured through the use of cryptography. Other methods are needed to guard against the threats such as denial of service or complete breakdown of information system.Another fundamental need of information security of

**selective access control**also cannot be realized through the use of cryptography. Administrative controls and procedures are required to be exercised for the same.Cryptography does not guard against the vulnerabilities and

**threats that emerge from the poor design of systems,**protocols, and procedures. These need to be fixed through proper design and setting up of a defensive infrastructure.Cryptography comes at cost. The cost is in terms of time and money −

Addition of cryptographic techniques in the information processing leads to delay.

The use of public key cryptography requires setting up and maintenance of public key infrastructure requiring the handsome financial budget.

The security of cryptographic technique is based on the computational difficulty of mathematical problems. Any breakthrough in solving such mathematical problems or increasing the computing power can render a cryptographic technique vulnerable.

## Future of Cryptography

**Elliptic Curve Cryptography** (ECC) has already been invented but its advantages and disadvantages are not yet fully understood. ECC allows to perform encryption and decryption in a drastically lesser time, thus allowing a higher amount of data to be passed with equal security. However, as other methods of encryption, ECC must also be tested and proven secure before it is accepted for governmental, commercial, and private use.

**Quantum computation** is the new phenomenon. While modern computers store data using a binary format called a "bit" in which a "1" or a "0" can be stored; a quantum computer stores data using a quantum superposition of multiple states. These multiple valued states are stored in "quantum bits" or "qubits". This allows the computation of numbers to be several orders of magnitude faster than traditional transistor processors.

To comprehend the power of quantum computer, consider RSA-640, a number with 193 digits, which can be factored by eighty 2.2GHz computers over the span of 5 months, one quantum computer would factor in less than 17 seconds. Numbers that would typically take billions of years to compute could only take a matter of hours or even minutes with a fully developed quantum computer.

In view of these facts, modern cryptography will have to look for computationally harder problems or devise completely new techniques of archiving the goals presently served by modern cryptography.