Posted at 12.31.2018
Cryptography was used only for armed service and diplomatic communication until the development of general public key cryptography. Secrecy is one of all important requirement of any communication and it becomes more important when this content of communication is perfect for military and diplomatic goal.
Hieroglyphs utilized by Egyptians are earliest known exemplory case of cryptography in 1900 BC. These hieroglyphics were used to create the stories of the life span of kings and summarize the great works of his life. Around 500 BC Hebrew scholars used mono alphabetic substitution cipher such as "Atbash cipher". Around 400 BC the Spartans also developed a "Scytale cipher" which used ribbons of parchment for writing any top secret concept after wrapping it around a cylindrical rod named as Scytale. In second century BC Greek historian Polybius invented "Polybius Square" a type of substitution ciphers. Around 1st century BC the Roman emperor Julius Ceaser used the substitution cipher called after him as "Ceaser Cipher". The Caesar Cipher is a Monoalphabetic type Cipher.
Around 9th century AD the Arab Mathematician Ab Ysuf Ya‰»qb ibn Isq al-Kind popularly known as "Al-Kindi" publicized the first text booklet on cryptnalysis of ciphers known as "Risalah fi Istikhraj al-Mu'amma (On Deciphering Cryptographic Announcements)". This reserve can be mentioned as the pioneer of the middle ages cryptography. In this particular book Al-Kindi identified the frequency analysis technique for deciphering substitution ciphers plus some polyalphabetic substitution ciphers. The relative frequency of icons is used in Frequency research to decode the communication. Al-Kindi used this technique on "Qur'an" to understand this is for religious goal.
The field of cryptography hadn't made any significant development until 15th century when the Italian mathematician Leon Battista Alberti known as "The Father of Western Cryptology, " developed the concept of polyalphabetic substitution. Although he had not made any practical cipher but employing this concept a functional Poly-Alphabetic substitution cryptographic system originated by French cryptographer BLAISE DE VIGENERE, which was called after him and called as VIGENERE SQUARE. For a long time this cipher was thought to be secure but around 1854, CHARLES BABBAGE, an British mathematician and engineer, better known as dad of Computer Technology for his development work of difference engine motor that end up being the first mechanical computer, successfully cracked the Vigenere Square Cipher utilizing the approach to statistical analysis.
Cryptography was widely used in World Conflict I and II. The most well-known occurrence of World Conflict I is of German overseas Minister Zimmerman Telegram that improved the whole World Warfare I and involved the America in world war which was natural till that date and Germany was finally defeated.
Unlike days gone by cryptographic algorithms where the main attention was on covering the algorithm or approach the modern ciphers needed the strategy or algorithm which can be trusted and whose security should not be affected if the algorithm is known.
To encrypt and decrypt the information, a key is utilized in modern cryptographic algorithms which convert the message and data in such format which are senseless to the receiver through encryption and then returning them to the initial form through decryption process.
Claude E. Shannon, dad of modern cryptography has contributed his work to cryptography in the form of "A mathematical theory of cryptography" and "A Marketing communications Theory of Secrecy Systems" which are believed as the foundation of modern cryptography.
In seventies the field of cryptography has observed two major innovations. First was the development of Data Encryption Standard (DES) by IBM, that was accepted as standard after some adjustment by the NSA in 1977 and it was later substituted by the Advanced Encryption Standard (AES) in 2001. The second development which is more important which changed the complete working process and use of cryptography is the development of Public Key Cryptography. It was started with the publication of the newspaper titled "New Guidelines in Cryptography", by Whitfield Diffie and Martin Hellman and similar development created by Ron Rivest, Adi Shamir and Leonard Adleman, who had been the first ever to publicly express the algorithm in 1977 and it was named after them as RSA algorithm.
The expression cryptology is a combo of two greek words, "kryptos", this means covered and "logos" means "study". Cryptology is really as old as writing itself and it has been primarily for a large number of years it turned out used for obtaining military services and diplomatic marketing communications.
The field of Cryptology can be further classified into two main domains, namely: Cryptography and Cryptanalysis. On the one hands the cryptographers make an effort to create a system or algorithm that'll be safe and sound for communication while on the other palm the cryptanalysts seek weaknesses in the developed system and try to breach the security of the system. Both works can be considered against each other however the work of cryptanalysts cannot be always negative plus they can work for the betterment of the developed system by trying to find out the weaknesses in the cryptographic algorithm and correct it.
Cryptography is the technique for writing secretly so that the unintended recipients cannot comprehend the original message. It transforms the information into such an unintelligible form so that illegitimate or unintended users cannot devise the initial interpretation of the concept and it appears like a garbage value for these people. But the primary consideration during the transformation is the fact the procedure must be reversible so the intended individual can get the original information after applying the original key and process. This is the traditional use of cryptography but in modern times the range of cryptography has widened.
Cryptanalysis is the field of research that deals with the techniques that verify and assert the security of the protocol or system. The aim of the cryptanalysis techniques is to assess the security says of the cryptographic algorithm or system. Cryptanalysts make an effort to develop an invasion showing that said security level is not achieved due to weaknesses in the cryptographic system.
It is difficult to define whenever a cryptosystem is busted. Generally, efficiency of the attack is weighed against the efficiency of exhaustive key search invasion and if the efficiency of attack is significantly less than after that it it is known as an episode on the cryptographic system.
Classification of episodes can be made based on the amount of information open to attacker:
Ciphertext-only harm: The attacker has usage of the ciphertext only.
Known-plaintext assault: In this case the attacker has access to both plaintext and the matching ciphertext. This episode can be employed when the attacker has limited usage of the encrypting device.
Chosen-Plaintext strike: The attacker chooses a plaintext and produces matching ciphertext using the correct key. This may only be applied if the attacker has access to encryption device and can encrypt a note of choice using this product. The goal of such type of attack is to find the trick key or algorithm for just about any given encrypted text message.
Chosen-Ciphertext attack: The attacker chooses a ciphertext and creates corresponding plaintext using the correct key. This may only be possible if the attacker has access to decryption device and can decrypt a message of preference using this product. The purpose of such kind of harm is also to find the secret key or algorithm for just about any given encrypted text.
The goals of such attacks on the whole can be grouped as magic formula key restoration, plaintext restoration without recovering the main element or the breakthrough of the encryption/decryption algorithm.
Unkeyed cryptosystem is that cryptosystem which will not use any key or parameter for program. Types of such system are one-way functions, cryptographic hash functions, and arbitrary bit generators.
Public Key or Asymmetric Key cryptography is the latest addition to the cryptographic techniques that has improved the basic uses of cryptography. Two different keys are being used for encryption and decryption in public areas or asymmetric key cryptography. General population key is being used for encryption which is known to everyone which is freely distributable however the encrypted message can only be decrypted by using the private key equivalent to general population key which is well known only to the approved person. General public key cryptography advanced to solve the problems of Magic formula key cryptography but it is very slow compared to key key cryptography. Public key cryptography cannot be used for high quantity encryption. Therefore we use mixture of Public and Private Key cryptography for practical applications.
In Symmetric Key or Magic formula Key cryptography, only an individual key is employed to encrypt and decrypt. Additionally it is called Private Key cryptography. The primary problem of the secret key cryptography is the writing of same key by sender and recipient. Regarding unsecure channels, there is absolutely no mean to switch key securely. The secret key must be shared using any secure channel before communication happen as well as for such purpose General public Key cryptography is normally used.
Symmetric key cryptography continues to be highly used because of its efficiency and is normally used where high volume of data is encrypted. Symmetric key primitives can be classified into two basic designs; specifically Stop Cipher and Stream Cipher.
Block cipher is a symmetric key encryption which divides the input blast of plaintext into resolved size of blocks, generally 64, 128 or 256 pieces long and utilizing a fixed transformation (substitutions and permutations) on every stop on by one. These transformations are repeated many times to acquire highly nonlinear outcome bits. The two most popular block ciphers are DES and AES.
A block cipher performs set transformations on any stop of data and leads to same ciphertext for same plaintext, hence can only just be considered secure for an individual stop of data. A method of operation is truly a way of encryption utilizing a block cipher securely for data several block. The Stop ciphers are used in one of the five modes to use for breaking the linearity. A cryptographic mode usually includes basic cipher, some sort of feedback, plus some simple businesses.
Electronic Code Book (ECB) Mode
Cipher stop Chaining (CBC) Mode
Cipher Opinions (CFB) Mode
Output Responses (OFB) Mode
The counter-top (CTR) Mode
Symmetric Cryptographic systems encrypt plaintext text messages unit by product, and unlike stop ciphers, which encrypt stop of plaintext using fixed transformation, Stream Ciphers encrypt specific units or persona of plaintext utilizing a time-varying change.
It takes the secret key and initialization vector (IV) as suggestions and produces a pseudo random sequence of digits called keystream using pseudo random generator, usually part of Stream Ciphers. ciphertext digits are generated by XORing the keystream digits with the plaintext digits.
The stream ciphers are labeled into two parts as synchronous and asynchronous stream ciphers on the basis of application of inner talk about in further encryption of digits. Stream ciphers have performed an important role in cryptography and still being used because of its efficiency and especially, in hardware implementations where hardware resources are constrained.
Stream ciphers are the key topic of research in this thesis and it will be mentioned more comprehensively in later chapters. For a general explanation of stream ciphers, see section 2.
Today the cryptology is not merely limited by data encryption and decryption as stated above, it includes an array of usages. The field of cryptology can be an emerging field where continuous expansions and adjustments are taking place. The field of cryptography was evolved for military consumption but it has expanded and is also highly found in civilian applications also. Cryptography is the analysis of numerical techniques, algorithms and protocols that provides four basic services for information security, particularly privacy, authentication, data integrity and non-repudiation.
Privacy or confidentiality: The basic goal of cryptography is to keep the information magic formula from unauthorized folks. Cryptography is the most typical mean to provide confidentiality or level of privacy to the information.
Data Integrity: Data integrity means that system must be able to discover the unauthorized manipulation of the data. Data manipulation identifies insertion, deletion or substitution of data.
Authentication: Authentication service supplies the ability to effectively identify the functions in the communication and origin of the data.
Non-Repudiation: Non-repudiation service stops an entity from denying any activity done by itself or existence of the communication at any later stage in case of any dispute.
Major effort towards standardization of cryptographic primitives was started out by European Payment research project funded from 2000-2003 in form of NESSIE (New European Strategies for Signatures, Integrity and Encryption). In March 2000 NESSIE urged the public for submissions of cryptographic primitives, and against this call 42 primitives were submitted in February 2003. The submissions were selected in different categories for standardization. Various cryptographic primitives were standardized except Stream Ciphers and none of them of the six submitted stream ciphers were considered as upto standard. During this period another firm, the International Standards Organization's ISO/IEC 18033 also initiated an identical task for standardization and decided on two stream ciphers: SNOW 2. 0 and MUGI. Other than these two work a Cryptography Research and Analysis Committee was create by japan Government which started out a job CRYPTREC in 2001 to evaluate and recommend the cryptographic primitives in different category for use. Inside the stream cipher category, three ciphers were recommended that are MUGI, MULTI-S01 and RC4 (128-tad keys only). But, Later on these ciphers were also found to be susceptible to the cryptanalytic attacks
This failure on the side of cryptographic primitives in stream cipher category prompted Adi Shamir in 2004 RSA Data Security Conference to question, whether there is a dependence on Stream Ciphers or not. He also defined two areas were Stream Ciphers can still be useful where exceptionally high throughput is necessary in software and exceedingly low resource consumption is required in hardware.
To explore the Stream Cipher condition and to develop a point out of artwork stream cipher which can secure and match the above mentioned requirements, ECRYPT launched the eSTREAM task in 2004.
eSTREAM made a demand distribution in two categories; hardware centered and software based mostly stream ciphers. In response to this call 34 ciphers were posted in both categories. In various phases of this project, cipher information were declared. The final profile released in January 2012, seven ciphers were preferred. The determined ciphers are HC-128, Rabbit, Salsa20/12 and SOSEMANUK in profile 1 (Software structured Ciphers) and Grain v1, MICKEY 2. 0 and Trivium in account 2 (Harware structured cipher). Even after these standardization initiatives, many weaknesses were within these ciphers.
This point out of Stream Ciphers has led me to involve in the research of the Stream Cipher and work at a secure and useful Stream Cipher.