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- 1. 1 A REVIEW STUDY OF CRYPTOGRAPHY TECHNIQUES NAVDEEP KAUR1 RUCHIKA JERATH2 1M.Tech (cse) pursuing, RIMT, Mandi Gobindgarh. 2Asst. Professor, Dept. of CSE, RIMT, Mandi Gobindgarh, Punjab, India ABSTRACT: Cryptography is a technique which provides security to the messages sent between sender and receiver on a network. Only authorized users can access the message. It helps to maintain the integrity of communication on a network. There are two main term of cryptography which are encryption and decryption. Encoding of message provided by Encryption and decoding of message provided by Decryption. Cryptography is a technique which provides security to our data by using two methods which are substitution and transposition encryption method. There are two main types of cryptography schemes used one is symmetric key cryptography which depends on single key value and asymmetric key cryptography which depends on pair of keys. Keywords: Cryptography, Substitution Techniques, Transposition Techniques, Symmetric Key Cryptography, Asymmetric Key Cryptography. 1. INTRODUCTION Cryptography is a technique to provide the security to data communication in the presence of third party. Every user wants a secure network to communicate that data should be secure and there is no intruder can read their data. Cryptography is used in Wireless and wired network for providing secure data communication. Cryptography converts the plain text into cipher text and cipher text into a plain text. Plain text is converted into a cipher text which is at a sender side known as encryption and cipher text is converted into a plain text which is at a receiver side known as decryption. Encryption converts readable form of message into unreadable form. Decryption converts unreadable form of message to readable form. Cryptography is divided into two types’ symmetric key cryptography and asymmetric key cryptography. Symmetric key cryptography use single key for encryption and decryption hence it is called as secret key cryptography and asymmetric key use pair of public and private key so it is called as public key cryptography. Cryptography services . A service that improve the security of the data processing systems. There are four type of services provided by Cryptography such as confidentiality, integrity, authentication, non-repudiation 1.1 Basics of Cryptography Cryptography provides security to the data during the transmission by performing some operations. The main aim of cryptography is to help user to hide information from unauthorized user. 1.1.1 ENCRYPTION Encryption is a technique which is converting a readable form of message into unreadable form which means conversion of plain text into cipher text. Encryption is performed when message is send by sender. The process of encryption is shown below fig. fig.process of encryption
- 2. 2 1.1.2 DECRYPTION It is a technique of cryptography which is converting an unreadable form of message into readable form which means that conversion of cipher text into a plain text known as decryption. Decryption is performed when message is received by receiver. The process of decryption is shown below fig. fig. process of decryption 2. ANALYSIS OF CRYPTORAPHICS TECHNIQUES: 2.1 Secret Key & Public Key Cryptography There are two keys are used in the cryptography which is secret key (symmetric cipher) and public key (asymmetric cipher). 2.2 SYMMETRIC KEY CRYPTOGRAPHY It is the one type of encryption algorithm which converts plain text into cipher text. It provides the security of data when data is transmission from one to another by using single secrete key. This secrete key is same to perform encryption and decryption. This key is known to only those users who are sending and receiving the message on that network. Secret key maintain the security of data therefore no other person access the data. Fig. process of symmetric key cryptography. Encryption algorithm is divided into two parts: Block Cipher : When messages are too long then it is difficult to encrypt the data then block cipher overcome this problem by the dividing the data into the fixed size of blocks. which are maybe 64 bit or 128 bit size of blocks. Encryption is performed on individual block by using same key. There are various modes of block cipher which are Electronic Code Book (ECB), Cipher Block Chaining (CBC), Cipher Feedback (CFB), and Output Feedback (OFB). Stream Cipher But in the stream cipher the data is encrypt within one digit block. It does not encrypt the whole digits within the block in one time, it encrypt only one digit at particular one time encryption. 2.3. ASYMMETRIC KEY CRYPTOGRAPHY It is also called as public key cryptography. Rather than using single key for encryption and decryption two different key are use for encryption and decryption. Where one key encrypt and other can decrypt. If sender sends a message then encryption is perform on sender side by using receiver public key and sends a message to the receiver. Only receiver can able to see a message and receiver decrypt a message by using receiver Private Key so security is maintained. Here key management is required. [1] Fig. Process of Asymmetric Key Cryptography.
- 3. 3 Table.1 advantage and disadvantage of symmetric cipher and asymmetric cipher [2] 2.4 DES (Data Encryption Standard): DES defined as a block encryption algorithm. It was the first encryption standard published by NIST (National Institute of Standards and Technology). It is a symmetric algorithm, means same key is used for encryption and decryption. It uses one 64-bit key. Out of 64 bits, 56 bits make up the independent key, which determine the exact cryptography transformation; 8 bits are used for error detection. The main operations are bit permutations and substitution in one round of DES. Six different permutation operations are used both in key expansion part and cipher part. Decryption of DES algorithm is similar to encryption, only the round keys are applied in reverse order. The output is a 64- bit block of cipher text. Many attacks and methods recorded the weaknesses of DES, which made it an insecure block cipher key [3] 2.5. 3DES (Triple DES): 3DES is an enhancement of Data Encryption Standard. It uses 64 bit block size with 192 bits of key size. The encryption method is similar to the one in the original DES but applied 3 times to increase the encryption level and the average safe time. 3DES is slower than other block cipher methods. [4] 2.6 AES (ADVANCED ENCRYPTION STANDARDS) The Advanced Encryption Standard (AES) is a symmetric-key block cipher algorithm, U.S. government standard for secure data and classified data for encryption and decryption.[5] In December 2001, the National Institute of Standards (NIST) approved the AES as Federal Information Processing Standards Publication (FIPS PUB) 197, which specifies application of the Rijndael algorithm to all sensitive classified data.[6] The AES has three fixed 128-bit block ciphers with cryptographic key sizes of 128, 192 and 256 bits. Key size is unlimited, whereas the block size maximum is 256 bits. The AES design is based on a substitution- permutation network (SPN) and does not use the Data Encryption Standard (DES) Feistel network.[7] The AES replaced the DES with new and updated features: Block encryption implementation 128-bit group encryption with 128, 192 and 256-bit key lengths Symmetric algorithm requiring only one encryption and decryption key Data security for 20-30 years Worldwide access No royalties Easy overall implementation 2.7 RSA (Rivest-Shamir-Adleman) RSA is a cryptosystem for public-key encryption, and is widely used for securing sensitive data, particularly when being sent over an insecure network such as the Internet. RSA was first described in 1977 by Ron Rivest, Adi Shamir and Leonard Adleman of the Massachusetts Institute of Technology. Public-key cryptography, also known as asymmetric cryptography, uses two different but mathematically linked keys, one public and one private. The public key can be shared with everyone, whereas the private key must be kept secret. In RSA cryptography, both the public and the private keys can encrypt a message; the opposite key from the one used to encrypt a message is used to decrypt it. This attribute is one reason why RSA has become the most widely used asymmetric algorithm: It provides a method of assuring the confidentiality, integrity, authenticity and non-reputability of electronic communications and data storage.[8] 3. CONCLUSION In this paper I have studied about cryptographic techniques and provide the security to data by hiding original data. It is prevent unauthorized user to access the data. It provide authentication to user to protect from unauthorized user. Cryptography is a best way for secure data. The process of encryption and decryption is the main mechanism which is working and guiding the flow of data. Reference: [1] Saykhede, A. et al. “A Survey Paper on Type and Method of Cryptography Technique” INTERNATIONAL JOURNAL FOR RESEARCH E-ISSN: 2349-7610 VOLUME-2, SPECIAL ISSUE- 1, MARCH-2015 [2] http://disp.ee.ntu.edu.tw
- 4. 4 [3] Juneja, M. et al. “A Review of Cryptography Techniques and Implementation of AES for Images” International Journal of Computer Science and Electronics Engineering (IJCSEE) Volume 1, Issue 4 (2013) ISSN 2320-401X; EISSN 2320-4028 [4] Juneja, M. et al “A Review of Cryptography Techniques and Implementation of AES for Images” International Journal of Computer Science and Electronics Engineering (IJCSEE) Volume 1, Issue 4 (2013) ISSN 2320-401X; EISSN 2320-4028 [5] https://www.techopedia.com [6] https://www.techopedia.com [7] https://www.techopedia.com [8] http://searchsecurity.techtarget.com