Cryptography and Network Security

Cryptography and Network Security

Cryptography can be defined as the conversion of data and information sent by a sender into an unreadable form and then back into a readable form once it gets to the intended recipient of the data or information. It is the method of protecting sent information from unauthorized access through the use of code that only authorized persons can understand.

In computer science, cryptography refers to the techniques used for the securing of data and information which involves the use of mathematical concepts and a set of rule-based calculations called algorithms to transform messages in ways that are hard to decipher. These algorithms are used for cryptographic key generation and digital singing verification to protect and secure web privacy on the internet and also confidential information such as credit card transactions and email.

A Brief History of Cryptography

The word cryptography itself was derived from the Greek word kryptos which means ‘hidden.’ The act of cryptography can be dated back to 2000 B.C when the ancient Egyptians used hieroglyphics which consisted of complex pictures that were only understood by the elite few. This very act can be explained to be cryptography.

The first occurrence of modern cipher can be traced back to Julius Caesar (100 B.C. to 44 B.C) who did not trust the messengers delivering his letters to his governors and officials, so he invented a system to keep his messages secret. To do this, he created a system in which all characters in his messages were replaced by a character three positions ahead of it in the Roman alphabet.

In recent times, mathematicians and computer scientists have become greatly involved in cryptography, as the significance of this aspect of data communication has become increasingly important. The ability to securely store information without any breach has become a very important factor in the success of war and business.

Due to the increasing significance of information and data security and, because the government of various countries does not wish certain entities inside and outside their country to have access to ways to receive and send information that may be a threat to national security, most countries have placed restrictions on the various aspects of cryptography. This restriction ranges from limitations on the usage and export of software to the public, to the dissemination of mathematical concepts that could lead to the development of cryptosystems.

Types of Cryptography

• Symmetric-key Cryptography

The symmetric-key cryptography also called the single-key cryptography is one of the simplest types of cryptography in the world. It involves the use of a single key by both the sender and the receiver. The sender uses this key to encrypt a plain text and sends the ciphered text to the receiver who uses the same key to decrypt the message sent and recover the plain text. This type of cryptography is not so efficient and secure, as if anybody intercepts such a message, such a person can easily use the key present in the message to decipher the message and obtain the message sent.

An example of the single-key cryptography includes the Advanced Encryption Standard (AES) which was established by the National Institute of Standards and Technology (FIPS 197) in November 2001 as a way of protecting sensitive information. This type of encryption is wildly used in the private sector.

• Public-key cryptography

This is the most revolutionary type of cryptography in the last 100 to 300 years. In this type of cryptography, two types of keys are used (public and private keys). The public-key in this type of encryption can be wildly distributed but it can only be used to decrypt a message when it is combined with the private key. Due to this, the private key is kept secret as this is what is most important to protect the information sent. In other words, the public key is used for encryption while the private key is used for decryption.

Types of the public-key include:

1. Elliptic Curve Digital Signature Algorithm (ECDSA) used by bitcoin

2. Digital Signature Algorithm (DSA) used by the Federal Information Processing Standard for digital signatures.

• Hush Functions

Here, no key is needed in the algorithm. A fixed-length hash value is computed as per the plain text that makes is possible for the contents of the plain text to be recovered. Hash functions are used by many operating systems to encrypt passwords.

The modern cryptography is majorly concerned with the following four objectives which includes

1. Confidentiality

The information sent must be protected from all unauthorized access from anyone whom the information is not intended.

2. Integrity

The information cannot be altered either in storage or in transit between the sender and the receiver without the change of alteration being noticed.

3. Authentication

The sender and the receiver can confirm each other’s identity and location or destination of the information.

4. Non-repudiation

This means that the creator of the sender of the information cannot at later stages deny his intention in the creation and the sending of such information.

Procedures or protocols that meet the above criteria are known as cryptosystems.

The importance of cryptography in modern technology can never be overemphasized. It is cryptography that makes all our daily business on the internet safe and credible. Without this cryptography, scammers will easily have access to our bank information, countries will not be able to protect confidential information digitally, and even our telephone or What’s app conversation will not be private anymore. In short, the whole internet will be a disaster waiting to happen.