### What is cryptography?

Cryptography is a method acting of protecting information and communications through the practice of codes, so that entirely those for whom the information is intended can read and process it .

In calculator science, cryptanalysis refers to secure information and communication techniques derived from mathematical concepts and a set of rule-based calculations called algorithm, to transform messages in ways that are hard to decipher. These deterministic algorithm are used for cryptanalytic key generation, digital sign, verification to protect data privacy, web browsing on the internet and confidential communications such as credit card transactions and e-mail .

### Cryptography techniques

cryptography is closely related to the disciplines of cryptanalysis and cryptanalysis. It includes techniques such as microdots, merging words with images and other ways to hide information in repositing or theodolite. however, in today ‘s computer-centric worldly concern, cryptography is most much associated with scrambling plaintext ( ordinary text, sometimes referred to as cleartext ) into ciphertext ( a process called encoding ), then back again ( known as decoding ). Individuals who commit this field are known as cryptographers .

mod cryptanalysis concerns itself with the following four objectives :

**Confidentiality.**The information cannot be understood by anyone for whom it was unintended.**Integrity.**The information cannot be altered in storage or transit between sender and intended receiver without the alteration being detected.**Non-repudiation.**The creator/sender of the information cannot deny at a later stage their intentions in the creation or transmission of the information.**Authentication.**The sender and receiver can confirm each other’s identity and the origin/destination of the information.

Procedures and protocols that meet some or all of the above criteria are known as cryptosystems. Cryptosystems are often thought to refer only to mathematical procedures and computer programs ; however, they besides include the regulation of human behavior, such as choosing hard-to-guess passwords, logging off fresh systems and not discussing sensitive procedures with outsiders .

Cryptography is the process of encrypting and decrypting data.

### Cryptographic algorithms

Cryptosystems use a fixed of procedures known as cryptanalytic algorithm, or ciphers, to encrypt and decrypt messages to secure communications among calculator systems, devices and applications .

A calculate suite uses one algorithm for encoding, another algorithm for message authentication and another for key exchange. This summons, embedded in protocols and written in software that runs on operating systems ( OSes ) and network computer systems, involves :

- public and private key generation for data encryption/decryption
- digital signing and verification for message authentication
- key exchange

### Types of cryptography

**Single-key or symmetric-key encryption** ** algorithms** create a fix duration of bits known as a obstruct nothing with a secret key that the creator/sender uses to encipher data ( encoding ) and the receiver uses to decipher it. One model of symmetric-key cryptography is the Advanced Encryption Standard ( AES ). AES is a specification established in November 2001 by the National Institute of Standards and Technology ( NIST ) as a Federal Information Processing Standard ( FIPS 197 ) to protect sensitive information. The standard is mandated by the U.S. government and widely used in the private sector .

In June 2003, AES was approved by the U.S. government for classify information. It is a royalty-free specification implemented in software and hardware global. AES is the successor to the Data Encryption Standard ( DES ) and DES3. It uses longer key lengths — 128-bit, 192-bit, 256-bit — to prevent animal power and other attacks .

Symmetric cryptography uses a single key while asymmetric cryptography uses a key pair to encrypt and decrypt data.

**Public-key or asymmetric-key encryption** ** algorithms** manipulation a pair of keys, a public key associated with the creator/sender for encrypting messages and a individual key that lone the originator knows ( unless it is exposed or they decide to share it ) for decrypting that information.

Examples of public-key cryptanalysis include :

- RSA, used widely on the internet
- Elliptic Curve Digital Signature Algorithm (ECDSA) used by Bitcoin
- Digital Signature Algorithm (DSA) adopted as a Federal Information Processing Standard for digital signatures by NIST in FIPS 186-4
- Diffie-Hellman key exchange

To maintain data integrity in cryptanalysis, **hash functions**, which return a deterministic end product from an input value, are used to map data to a fixed data size. Types of cryptanalytic hash functions include SHA-1 ( Secure Hash Algorithm 1 ), SHA-2 and SHA-3 .

### Cryptography concerns

Attackers can bypass cryptography, hack into computers that are responsible for data encoding and decoding, and exploit fallible implementations, such as the consumption of default option keys. however, cryptanalysis makes it harder for attackers to entree messages and data protected by encoding algorithm .

Growing concerns about the processing exponent of quantum computing to break current cryptography encoding standards led NIST to put out a call for papers among the mathematical and skill community in 2016 for raw public samara cryptanalysis standards .

Unlike today ‘s calculator systems, quantum computing uses quantum bits ( qubits ) that can represent both 0s and 1s, and consequently perform two calculations at once. While a large-scale quantum computer may not be built in the following ten, the existing infrastructure requires calibration of publicly known and understand algorithm that offer a dependable access, according to NIST. The deadline for submissions was in November 2017, analysis of the proposals is expected to take three to five years .

### History of cryptography

The word “ cryptography ” is derived from the Greek kryptos, meaning concealed .

The prefix “ crypt- ” means “ hide ” or “ vault, ” and the suffix “ -graphy ” stands for “ write. ”

The lineage of cryptography is normally dated from about 2000 B.C., with the egyptian practice of hieroglyphics. These consisted of complex pictograms, the entire mean of which was lone known to an elite few .

The first known habit of a advanced cipher was by Julius Caesar ( 100 B.C. to 44 B.C. ), who did not trust his messengers when communicating with his governors and officers. For this reason, he created a organization in which each character in his messages was replaced by a character three positions ahead of it in the Roman alphabet.

Read more: A Few Thoughts on Cryptographic Engineering

In recent times, cryptography has turned into a battlefield of some of the world ‘s best mathematicians and calculator scientists. The ability to securely store and transfer sensitive data has proved a critical factor in success in war and business .

Because governments do not want certain entities in and out of their countries to have access to ways to receive and send hidden information that may be a threat to national interests, cryptanalysis has been subjugate to versatile restrictions in many countries, ranging from limitations of the usage and export of software to the public dispersion of numerical concepts that could be used to develop cryptosystems .

however, the internet has allowed the dispersed of potent programs and, more importantly, the underlying techniques of cryptanalysis, so that today many of the most promote cryptosystems and ideas are nowadays in the public domain .