Cryptography
 Summary

Discussion
 What is the purpose of cryptography?
 What are some wellknown applications of cryptography?
 Which are some commonly used terms in cryptography?
 What techniques can be used for encrypting/decrypting data?
 Could you share examples of cryptographic algorithms?
 How do I evaluate cryptographic algorithms?
 What is the role of computational and energy costs in implementing Cryptography?
 Milestones
 References
 Further Reading
 Article Stats
 Cite As
Cryptography is a set of techniques for encrypting data using specified algorithms that make the data unreadable to the third party computer systems, unless decrypted using predefined procedures by the sender.^{} Messages between the sender and receiver are passing through a medium, which may be attacked and the information can be stolen. So the sender encrypts and the receiver decrypts. In the presence of third parties, cryptography is the practise of secure communication.^{} Data encryption is known for its ability to keep information safe from prying eyes. It uses an encryption key to convert data from one format, called plaintext, to another, called ciphertext. Modern cryptography is largely based on computer science's mathematical theory and practise.^{}
Discussion

What is the purpose of cryptography? A system's ability to verify the sender's identity is Authentication. The sender and recipient can verify each other's identities as well as the information's origin and destination.^{} ^{}
Information transmitted should only be accessed by legal parties and not by anyone else for the purpose of Confidentiality. Anyone who was not intended to get the information will be unable to comprehend it.^{} ^{}
Only authorised parties are allowed to make changes to transmitted data to maintain Integrity. Information cannot be manipulated with while in storage or in transmission between the sender and the intended recipient without being detected.^{} ^{}
Nonrepudiation is the guarantee that no one can refute something's legitimacy. The information creator/sender cannot later contradict their intentions in the development or transmission of the material.^{} ^{}
The information provided is only accessible to those who have been given permission. This gives Access Control only to the involved parties.^{}

What are some wellknown applications of cryptography? Protected Communication: Encrypting communications between ourselves and another system is the most common application of cryptography, and one we all use on a regular basis. A web browser and a web server are two examples, as are an email client and an email server. Modern switching networks make interception more difficult.^{}
Storage Integrity: The emergence of computer viruses has led to the adoption of cryptographic checksums for data storage. A checksum is generated and compared to expectations, just as it is for transmission integrity. Transmitted information is often available for a shorter amount of time and is used for a smaller volume of data, and is retrieved at a slower rate than stored data.^{}
Electronic Money: Today, there are patents in existence around the world that allow electronic information to substitute cash money in individual financial transactions. Cryptography is used in this system to keep national assets in electronic form.^{}

Which are some commonly used terms in cryptography? Plaintext refers to any communication or data that has to be protected for various reasons.^{}
Ciphertext is the unreadable form of data that is generated at the end of the encryption process.^{}
Encryption refers to the process of encoding a message with the use of a key. The basic text is turned into illegible text in this way.^{}
Decryption is the process of deciphering an encoded communication with the use of a key. It's the inverse of the encryption method.^{}
A key is a parameter that dictates what a cryptographic process's final output will be. The length of the key is important in the encryption process.^{}

What techniques can be used for encrypting/decrypting data? When Symmetric Encryption is performed, the same cryptographic keys are utilised for plaintext crypting and degradation of the figure materials. Symmetrical key encryption is less complicated. One key is used to encrypt and decrypt both data sets. Types of symmetric keys: Stream or Block cyphers, can be used in symmetrickey encryption. Stream cyphers encrypt the digits of a message one by one (typically bytes). To modify the component's measurement, Block figures employ distinct sections and encrypt them with the plaintext as a single component unit.^{}
Asymmetric Encryption is a collection of keys that are used to encrypt and decrypt public and privatekey information.
Because the user utilises two keys as asymmetrical encoding employs two keys, it's also known as the Cryptography Public Key.^{}
In Encryption with public keys the messages are encrypted using the recipient's public key. The post cannot be deciphered by anyone who is not the private coordinator, does not own the key, or is not connected to the general public key.^{}
Digital Signature uses a personalised transmitter key that can be verified by anyone with a personal key, ensuring network security.^{}

Could you share examples of cryptographic algorithms? Data Encryption Standard (DES) developed by IBM in the 1970s, approved for commercial usage by the National Bureau of Standards(NBS) in 1977 uses a 56bit key and 8 rounds to work on 64bit blocks.^{}
Advanced Encryption Standard (AES) is a fast and safe algorithm released in 1998, created by Vincent Rijmen and Joan Daemen works with variable key and block lengths. The key length can be 128, 192, or 256 bits, and the block length can be 128, 192, or 256 bits.^{}
Rivest Cipher (RC) was created by Ronald Rivest, and named after him. RC1, RC2, RC3, RC4, RC5, and RC6 are available.
Bruce Schneie created Blowfish in 1993 and published it in 1994. It contains 8 rounds, with a 64bit block size and a key length of 32 to 448 bits. Blowfish is considered as a replacement for DES as it is substantially faster than others with a good key strength.
RSA was named after it's inventors Ron Rivest, Adi Shamir and Leonard Adleman, in 1997. A variablesize key and encryption block are employed in it. It provides increased security and convenience, and uses Public Key Encryption.

How do I evaluate cryptographic algorithms? Each encryption algorithm has strengths and disadvantages, that affect encryption performance based on these parameters:
Encryption time is measured in milliseconds and depends on the data block's length and key. When the encryption time is short, an algorithm's performance is considered advanced.^{}
Decryption time is the amount of time it takes to recover the original text from ciphertext, measured in milliseconds. When the decryption time is short, an algorithm's performance is considered superior.^{}
Memory used should be minimal because it has an impact on system costs.^{}
Throughput is calculated by dividing the total encoded block size by the whole encode time. If the throughput cost rises, the algorithm's power consumption will fall.^{}
Avalanche effect predicts that if the plaintext changes, the ciphertext will also change dramatically, by calculating the difference between plaintext and ciphertext modifications.^{}
Entropy is a statistical measure of data randomness and uncertainty..^{}
The number of bits required for encoding optimally defines the bandwidth required for transmission. When an encrypted character or bit is encoded with fewer bits, it uses less storage and bandwidth, directly impacting the system's cost.^{}

What is the role of computational and energy costs in implementing Cryptography? Networks are developing towards a ubiquitous model in which heterogeneous devices are networked (offering easy network interconnections anytime and anyplace). Cryptographic algorithms are necessary for the network security solutions' development. However, network devices' computational and energy restrictions make real implementation of such processes difficult. As a result, a thorough examination of the costs of launching symmetric and asymmetric cryptographic algorithms, hash chain functions, elliptic curve cryptography, and pairingbased cryptography on personal agendas is carried out, and the results are compared to the costs of basic operating system functions. The studies reveal that, while cryptographic power costs are considerable and such operations must be time limited, they are not the primary limiting factor in a device's autonomy.^{}
The technological advancement has resulted in the expansion of personal portable computers and the emergence of new forms of networks. Security solutions are required to secure heterogeneous ubiquitous networks generated by small and restricted devices, which are being explored or are already in use. The inherent nature of ubiquitous networks requires the safeguards' implementation to assure proper protocol execution at all layers, from networking operations to collaborative enforcement protocols or privacyprotecting mechanisms.^{}
Milestones
Polish cryptographer Marian Rejewski discovers how Enigma works.^{}
Poland shares the information on how Enigma works with the French and British intelligence services, allowing cryptographers like Alan Turing to figure out how to crack the key, which changes daily. It proves crucial to the Allies' World War II victory.^{}
Claude E. Shannon of Bell Labs publishes an article called "A mathematical theory of cryptography." It's the starting point of modern cryptography. For centuries, governments have controlled secret codes: applied to diplomacy, employed in wars, and used in espionage. But with modern technologies, the use of codes by individuals is exploding.^{}
Whitfield Diffie and Martin Hellman publish a research paper, New Directions in Cryptography, on what would be defined as the DiffieHellman key exchange. For the first time, the code key is no longer prearranged, but a pair of keys (one public, one private but mathematically linked) is dynamically created for every correspondent.^{} ^{}
RSA public key encryption is invented.^{}
Robert McEliece invents the McEliece cryptosystem, the first asymmetric encryption algorithm to use randomization in the encryption process.^{}
The Advanced Encryption Standard replaces DES, or AES (asymmetric key  the user and sender must know the same secret key), found through a competition open to the public. Today, AES is available royaltyfree worldwide and is approved for use in classified US government information. PKI (Public Key Infrastructure) is a generic term used to define solutions creating and managing publickey encryption. It is activated by browsers for the Internet but also by public and private organizations to secure communications.^{}
Belgian Rijndael algorithm selected as the U.S. Advanced Encryption Standard (AES) after a fiveyear public search process by National Institute of Standards and Technology (NIST).^{}
The first commercial quantum cryptography system becomes available from id Quantique.^{}
Ellipticcurve cryptography (ECC) is an advanced publickey cryptography scheme and allows shorter encryption keys. Elliptic curve cryptosystems are more challenging to break than RSA and DiffieHellman.^{}
Users swamp Digg.com with copies of a 128bit key to the AACS system used to protect HD DVD and Bluray video discs. The user revolt is a response to Digg's decision, subsequently reversed, to remove the keys, per demands from the motion picture industry that cited the U.S. DMCA anticircumvention provisions.^{} NIST hash function competition announced.^{}
Edward Snowden discloses a vast trove of classified documents from NSA. Dual_EC_DRBG is discovered to have a NSA backdoor. NSA publishes Simon and Speck lightweight block ciphers.^{}
References
 Abood, Omar G, and Shawkat Guirguis. 2018. "Enhancing Performance of Advanced Encryption Standard for Data Security." ResearchGate, November. Accessed 20220603.
 Alemami, Yahia, Mohamad Afendee Mohamed, and Saleh Atiewi. 2019. "Research on Various Cryptography Techniques." International Journal of Recent Technology and Engineering (IJRTE). Accessed 20220222.
 Brush, Kate, Linda Rosencrance, and Michael Cobb. 2021. "What is asymmetric cryptography?" TechTarget. Accessed 20220603.
 Chamberlain, Austin. 2017. "Applications of Cryptography." UCLUniversity College London, March. Accessed 20220330.
 Cohen, Fred. 1995. "2.4  Applications of Cryptography." all.net. Accessed 20220330.
 Jyothi, V. Esther, Dr. BDCN Prasad, and Dr Ramesh Kumar Mojjada. 2020. "Analysis of Cryptography Encryption for Network Security." IOP Conference Series: Materials Science and Engineering. Accessed 20220223.
 Lemon, Sumner. 2007. "Digg bends to users' will on AACS encryption key." InfoWorld. Accessed 20220331.
 Malhotra, Mini, and Aman Singh. 2013. "Study of Various Cryptographic Algorithms." International Journal of Scientific Engineering and Research (IJSER). Accessed 20220225.
 Mushtaq, Muhammad Faheem, Sapiee Jamel, Abdulkadir Hassan Disina, and Zahraddeen Abubakar Pindar. 2017. "A Survey on the Cryptographic Encryption Algorithms." International Journal of Advanced Computer Science and Applications. Accessed 20220222.
 Prasetyo, Kenang Eko, Tito Waluyo Purboyo, and Randy Erfa Saputra. 2017. "A Survey on Data Compression and Cryptographic Algorithms." International Journal of Applied Engineering Research. Accessed 20220222.
 Qadir, Abdalbasit Mohammed, and Nurhayat Varol. 2019. "A Review Paper on Cryptography." IEEE. Accessed 20220222.
 RifaPous, Helena, and Jordi HerreraJoancomart´. 2011. "Computational and Energy Costs of Cryptographic Algorithms on Handheld Devices." MDPI  Future Internet, February. doi: www.mdpi.com/19995903/3/1/31. Accessed 20220524.
 Sahu, Aditya Kumar, and Monalisa Sahu. 2020. "Digital image steganography and steganalysis: A journey of the past three decades." De Gruyter. Accessed 20220623.
 Singh, Prabhsimran, Sukhmanjit Kaur, and Sabia Singh. 2015. "Cryptography: An Art of Data Hiding." International Journal of Computer and Communication System Engineering (IJCCSE). Accessed 20220603.
 Thales. 2021. "A brief history of encryption." Thales, October. Accessed 20220331.
 V, Gahan A, and Geetha D Devanagavi. 2019. "A Empirical Study of Security Issues In Encryption Techniques." International Journal of Applied Engineering Research. Accessed 20220222.
 Wikipedia. 2005. "Timeline of cryptography." Wikipedia, the free encyclopedia. Accessed 20220331.
Further Reading
 Zwicke, Andrew. 2003. "An Introduction to Modern Cryptosystems." GIACGlobal Information Assurance Certification. Accessed 20220331.
 Singh, Simon. 2000. "The code book : the science of secrecy from ancient Egypt to quantum cryptography." Anchor. Accessed 20220331.
 Diffie, Whitfield, and Martin Hellman. 1976. "New Directions in Cryptography." IEEE Transactions on Information Theory. Accessed 20220331.
 Smart, Nigel. 2002. "Cryptography: An Introduction." American Mathematical Soc. Accessed 20220331.
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See Also
 Public Key Cryptography
 Quantum Cryptography
 Cryptocurrency
 SQL Injection
 Web Exploitation
 Network Security
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