Cryptography Notes

Secret Key Cryptography and Public Key Cryptography Review

Abstract

• This paper reviews secret key and public key cryptography algorithms.
• Discusses cryptography's importance in data security.
• Traces the history of cryptography back to ancient times and wars.
• Notes that while cryptography has advanced, it is still not perfect.
• In secret-key cryptography, private keys are used for both encryption and decryption, and are shared between sender and receiver, offering faster performance as part of symmetric cryptography.
• In public-key cryptography, public keys are used only for encrypting data, with a shared private key needed for decryption.

Introduction

• Public Key Cryptography (PKC) secures communication by using key pairs: a public key for encryption and a private key for decryption.
• PKC enables secure data exchange over insecure channels without shared secret keys.
• Cryptography involves data hiding or encryption so only the intended recipient can interpret it.
• Cryptography has been used since ancient times and is now used in e-commerce, password management, and card payments.

Literature Survey

• Neal Koblitz et al. proposed elliptic curve cryptosystems for secure communication on insecure networks.
  • These systems use elliptic curves over finite fields.
  • They are more secure because the discrete logarithm problem on elliptic curves is harder than the classical discrete logarithm problem.
  • The scheme is based on the multiplicative group of a finite field.
• Hugo Krawczyk et al. worked on encryption and authentication schemes for communication protection.
  • They introduced an entity authentication and symmetric encryption scheme.
  • This scheme constructs secure channels to protect communications over hostile networks.
  • They showed that the authenticated encryption approach was not secure against random attacks.
  • The limitation was a forty-bit key size.
• Laurent Eschenauer et al. proposed a key-based scheme for distributed sensor networks.
  • The key management scheme satisfies operational and security requirements.
  • Requirements include cryptographic protection, sensor capture detection, key revocation, and sensor disabling.
• Lo et al. proposed an efficient key management scheme in a large leaf class hierarchy for access control.
  • Users are divided into different security classes.
  • A new key assignment scheme reduces the computation needed for key generation.
  • Information retrieval and the amount of leaf classes are much greater than non-leaf classes.
• Bharat B. Madan et al. worked on different approaches to model and quantify the security attributes of intrusion-tolerant systems.
  • They covered problems concerning the quantification of security attributes of intrusion-tolerant systems.
  • The response of a security intrusion-tolerant system to an attack was modeled as a random process.
  • They facilitate utilizing stochastic modeling techniques to predict attacker behavior.
• Tariq Jamil et al. worked on the Rijndael method/algorithm for protecting sensitive unclassified government information.
  • This algorithm is a new Advanced Encryption Standard (AES) algorithm recommended by the US National Institute of Standards and Technology.
  • Performance of the Rijndael algorithm is based on the speed of encryption, decryption process, and key setup time.
• Ho Won Kim et al. worked on the design and implementation of a private and public key crypto processor and its application for security systems.
  • They present a design and implementation of a crypto processor, a special-purpose microprocessor optimized to execute cryptography algorithms.
  • This crypto processor can be used in storage devices, embedded systems, network routers, and security applications.
• Prosanta Gope et al. have been developing a new block cipher cryptographic symmetric key algorithm called TACIT encryption technique for secure routing.
  • It used an independent approach with suitable mathematics assumed to be computationally secured.
  • Key distribution system was being applied on a secure policy-based routing.
  • It was limited to text file conversion.
• Ismail .I.A et al. researched how to fix the Hill cipher.
  • This method changes the key after a few characters to get a different key for each block encryption.
  • It is much stronger against known plain text attacks and statistical attacks.
  • The new suggested algorithm is called HillMRIV cipher.
• Yogesh Karandikar et al. proposed an effective key management approach for differential access control in dynamic environments.
  • In group communication, each user accesses multiple resources, and many users can access each resource.
  • Every subscriber of a resource must be distributed each resource encryption key, and every subscriber must receive the entire key.
  • They developed a new approach of key management to enforce differential access controls in highly dynamic environments for secure group communication framework.
• Yanchao Zhang et al. worked on Location-Based Compromise-Tolerant Security Mechanisms for Wireless Sensor Networks.
  • They worked on the notion of location-based keys by binding private keys of individual nodes to both their IDs and geographic locations.
  • They developed an LBK-based neighborhood authentication scheme to localize the impact of compromised nodes to their vicinity.
• N. R. Potlapally et al. worked on energy consumption characteristics of cryptographic algorithms and security protocols.
  • They provide a detailed analysis of the energy demands of a large variety of implemented cryptographic algorithms.
  • They also discuss opportunities for energy-efficient implementations of security protocols.
• Darpan Anand et al. studied techniques and applications related to identity-based cryptography.
  • They looked at various applications of identity-based encryption to the problems associated with variation networks, such as ad-hoc networks.
  • The scheme is then used in mobile networks and other wireless networks.
  • They discussed the benefits and limitations of identity-based cryptography.
  • The main limitation was that the available methods were restricted to a fixed output block.
• Pavan. N et al. presented another scheme in image steganography using the Hill cipher for key hiding.
  • They implemented the Hill cipher algorithm for hiding text behind a cover image and decrypting the cover image to get the original text.
  • The key being encrypted and scrambled in the cover image scheme eliminates the use of a key distribution system.
  • This makes the system highly secure for the various network applications.
• Kundan Kumar Rameshwar Saraf et al. wrote a paper titled "Text and Image Encryption Decryption Using Advanced Encryption Standard".
  • AES has its own limitation.
  • With slight variation in the method AES can be used for the protection of the Images as well as text.
  • They implemented encryption and Decryption for text and image using AES.
• A paper "Image Encryption and Decryption using Blowfish Algorithm was written by al. [19].
  • They have written a paper about encryption and decryption of images using a secret-key block cipher called 64-bits Blowfish.
  • It was designed for increased security and to improve performance.
  • It employs the algorithm with a variable key size of up to 448 bits; this uses the Feistel network.
  • It iterates simple function 16 types.
  • "The blowfish algorithm is safe from unauthorized attack and runs faster than the popular existing algorithms".
• B. Persis described that "most of the web based applications requires a security for the data, number of symmetric and Asymmetric algorithms approaches with maximum protection for the data to be transferred.
  • This paper narrates about the design and implementation of simplified algorithm based on Data Encryption Standard (DES) algorithm though it resembles its almost looks similar to it but functions in a different way.
  • The data to be encrypted is manipulated with the private key that is created".
• D.Maheswari et. al told that "in recent years the need of security has increased many folds.
  • Cryptography is an answer today for secure communication and password management.
  • It embraces two mechanisms: encryption and decryption.
  • In cryptography, mathematical principles can be used in order to encrypt and decrypt our message, making them secure in transit.
  • In this paper, we propose to use principles of Hill Cipher for developing an algorithm of Encryption and Decryption to make Transmission of Messages secure from eavesdropping".
• Ali Mohammed et. AL defined that Nowadays security is very important to protect our sensitive information in computer or over the internet such as in online banking, online shopping, stock market and bill payments etc.
  • Without security our information exchanged over internet are not safe.
  • Encryption Algorithms provides the security to the information which is exchanged over the internet.
  • "In this work, we are proposing a new cryptographic algorithm AEDS (Advanced Encryption and Decryption Standard), which is developed by combining properties of DES and AES algorithms.
• Borislav Stoyanov et. al described that "An improved encryption algorithm based on numerical methods and rotation–translation equation is proposed".
  • We are going to develop the new encryption-decryption algorithm using the concept of symmetric key instead of public key.
  • Symmetric key algorithms use the same key for encryption and decryption.
  • Most of the symmetric key encryption algorithms use either the block ciphers or the stream ciphers.
  • Our objective in the work is to upgrade an existing encryption algorithm with the use of a faster convergent iterative method for providing secure convergence of the corresponding numerical scheme, and improved security by use of a rotation – translation formula".
• Subhi et. al described that Nowadays there is a lot of importance given to data security on the internet.
  • DES is one of the more popular block cipher encryption/decryption procedures applied at present.
  • In this paper, a high throughput hardware implementation of the DES Encryption algorithm in a reconfigurable hardware implementation is presented.
  • It is accomplished using a new proposed implementation of the DES algorithm based on the pipelined concept.
  • The decryption implementation of the proposed design is implemented using Spartan-3E (XC3S500E) family FPGAs and proves to be one of the fastest hardware implementations with far greater security.
  • "At a clock frequency of 167.448MHz for encryption and 167.870MHz for decryption, it can encrypt or decrypt data blocks at a rate of 10688Mbps".
• Pronika et. Al mentioned in status that "In this tumultuous 21st century, we are surrounding by lots of applications such as social media websites all over the internet or this era can also define as digital era in which everything is accessible over the internet".
  • There are billions of people using the internet all over the world and they share their information over the same, and because of this, lots of peop

Secret Key Cryptography

• In secret key cryptography, the plaintext message to be encrypted is decoded using a collection of bits called the secret key.
• Because the same key is used to decode the text message, it is often referred to as a symmetric key.
• The secret key is also a part of the encryption algorithm in cryptography since it is the first comprehensible message or piece of data supplied into the encryption process as input.
• Plaintext is unrelated to an algorithm value known as the main. Depending on the key, the approach produces different outcomes.
• The technique makes advantage of the key to exact substitution and alteration.
• Two distinct ciphertexts produced by two different keys can be constructed for the same letter.
• As of right now, the ciphertext is a stream of nearly random information.
• After the secret key distribution issue is resolved, secret key cryptography can be useful.
• Algorithms are very safe and efficient in encrypting data.
• Most sensitive data transmitted over an SSL session is encrypted with a secret key.
• The usage of secret-key cryptography is beneficial. The methods provide very high privacy and speedy data encryption.
• Most of the private data sent during a TLS transaction is sent via secret-key cryptography.
• Secret key cryptography is sometimes called symmetric cryptography since just one key is needed for both data encryption and decryption.
• Cryptographic techniques include Data Encryption Standard (DES), triple-strong DES (3DES), Rivest Cypher 2 (RC2), and Rivest Cypher 4 (RC4).
• Diagram Fig 1 Secret-Key Cryptography

Types of Cryptography

The majority of authors and researchers categorize cryptography into three main groups:

Cryptology Using Secret Keys

• Also known as Secret Key or Symmetric cryptography.
• Uses a single key for both encryption and decryption.
• The key used to convert plain text into cypher text may also be used to reverse the cypher text back into plain text.

Algorithm Types

Secret Key Cryptography (SKC)

• Encrypts and decrypts data using just one key.
• Schemes fall into two categories: block cyphers or stream cyphers.
• Block cypher schemes encrypt one block of data at a time using the same key on each block, whereas stream cyphers work on a single bit (byte or computer word) at a time and employ some sort of feedback mechanism to ensure that the key is continuously changing.
• Propagation error is the primary disadvantage of this approach since a distorted bit during transmission would produce n distorted bits at the receiving end.
• Stream cyphers are periodic, therefore even though they don't spread transmission mistakes, the key-stream will ultimately repeat.
• This typically leads to the usage of TTPs or big keys for the public verification function in digital signature methods.

Public Key Cryptography (PKC)

• Encrypts data using a single key and decrypts it using a separate key.
• The earliest description of modern PKC used a two-key cryptosystem, which allowed two parties to communicate securely across an insecure channel without disclosing their secret key to one another.
• One of the keys in PKC is called the public key, and its owner is free to distribute it as widely as they choose. The other key is kept secret and is referred to as the private key.
• One of the earliest and most widely used PKC implementations for digital signatures and key exchange is RSA.
• This method's primary benefit is that, instead of requiring an unconditionally trusted TTP, key administration on a network simply requires the presence of a functionally trusted TTP. The TTP may only be needed "off-line," as opposed to in real time, depending on how it is used.
• Numerous public-key cryptosystems produce comparatively effective signature techniques. Compared to its symmetric-key cousin, the key used to specify the public verification function is usually substantially smaller.

Hash Functions (HF)

• To permanently "encrypt" data, the HF applies a mathematical modification.
• This algorithm encrypts and decrypts data without the need for keys.
• Instead, it makes use of a fixed-length hash value that is calculated from a plaintext, making it difficult to retrieve the plaintext's length or contents.
• These techniques are commonly employed to generate a digital fingerprint of a file's content, which is frequently used to verify that a virus or other unauthorized party hasn't changed the file.
• Many operating systems also frequently use hash algorithms to encrypt passwords in order to offer a degree of file integrity.

Conclusion

• A predetermined cryptographic key, or collection of keys, is used in both public-key and secret-key cryptography.
• A key is a collection of bits that an algorithm or cryptographic technique uses to encrypt and decode data.
• A cryptographic key is like a lock key in that it can only be unlocked with the right key.
• A description of the encryption method's general methodology is given. Next, in order to verify the security complexity of each encryption method, a comparison analysis is conducted. Additionally, the study is carried out using a program to guarantee a satisfactory degree of security for data transmission and time.
• Since data encryption research is still in its infancy, there will likely always be new encryption techniques developed along with a growing number of attacks. As a result, future research efforts will focus on confirming these techniques' efficacy.