An Efficient Algorithm on Text Based Data Encryption ...

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text using a secret key and an encryption algorithm. ... encrypting or signing messages. ... Digital signatures are usually applied to hash values as these are ...
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An Efficient Algorithm on Text Based Data Encryption System Tanmoy Kumar Bishoi a and Ramkrishna Ghosh b,* a

Global Institute of Science Technology, Haldia, WB, INDIA b Haldia Institute of Technology, Haldia, WB, INDIA E-mail: [email protected]

Abstract: Security is the most challenging aspects in the internet and network applications. Cryptography is one of the main categories of computer security that converts information from its normal form into an unreadable form. Encryption is a process of generating secret text from the input text using a secret key and an encryption algorithm. The two main aspects that identify and evaluate one encryption algorithm from another are its ability to secure the data against attacks and its speed and efficiency in doing so. Input text is referred to as plain text and the secret text generated is known as cipher text. In this paper, we present a technique based on key encryption algorithm which uses ASCII vales of input text to encrypt the data. Keywords: Encryption, Decryption, ASCII, Strings, Plain Text, Cipher Text, Symmetric key, Asymmetric key 1. Introduction Cryptography is the practice and method for secure communication in the presence of third parties called adversaries. More precisely, it is about constructing an analyzing protocol overcoming the influence of adversaries and which are related to various aspects in information security such as data confidentiality, data integrity, and authentication. Applications of cryptography include ATM cards, computer passwords, and electronic commerce. A cryptographic algorithm, or cipher, is a mathematical function used in the encryption and decryption process. This algorithm works in combination with a key; that may be a word, number, or phrase; to encrypt the plaintext. The same plaintext encrypts to different cipher text with different keys. The security of encrypted data is entirely dependent on the strength of the algorithm and the secrecy of the key. There are two main types of cryptography. Those are public-key and private-key. Public-key is a form of cryptography in which two digital keys are generated, one is private, which must not be known to another user, and one is public, which may be made available in public. These keys are used for either encrypting or signing messages. The public-key is used to encrypt a message and the private-key is used to decrypt the message. However, in another scenario, the private-key is used to sign a message and the public key is used to verify the signature. The two keys are related by a hard one-way (irreversible) function, so it is computationally infeasible to determine the private key from the public key. 2. Literature Survey 2.1 Encryption And Decryption There are two main types of cryptography. They are Secret Key Cryptography which is also known as Symmetric Key Cryptography and Public Key Cryptography which is also known as Asymmetric Key Cryptography. 2.1.1 Symmetric-Key Encryption In this process, the encryption key can be calculated from the decryption key and vice versa. With most symmetric algorithms, the same key is used for both encryption and decryption.

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Figure (a): Symmetric-Key Encryption

Symmetric-key encryption can be highly efficient, so that users do not experience any significant time delay. It also provides a degree of authentication, since message encrypted with one key cannot be decrypted with any other symmetric key. 2.1.2 Asymmetric-Key Encryption Asymmetric encryption comprises a pair of keys, a public key and a private key, associated with an entity. Each public key is published, and the corresponding private key is kept secret.

Figure (b): Asymmetric-Key Encryption

To send encrypted data, the data is encrypted with that person's public key, and the person receiving the encrypted data decrypts it with the corresponding private key. Compared with symmetric-key encryption, public-key encryption requires more processing and may not be feasible for encrypting and decrypting large amounts of data. 2.2 Confidentiality To ensure data remains private. Confidentiality is usually achieved using encryption. Encryption algorithms (that use encryption keys) are used to convert plain text into cipher text and the equivalent decryption algorithm is used to convert the cipher text back to plain text. Symmetric encryption algorithms use the same key for encryption and decryption, while asymmetric algorithms use a public/private key pair. 2.3 Data integrity To ensure data is protected from accidental or deliberate (malicious) modification. Integrity is usually provided by message authentication code or hashes. A hash value is a fixed length numeric value derived from a sequence of data. Hash values are used to verify the integrity of data sent through insecure channels. The hash value of received data is compared to the hash value of the data as it was sent to determine if the data was altered.

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2.4 Authentication To assure that data originates from a particular party. Digital certificates are used to provide authentication. Digital signatures are usually applied to hash values as these are significantly smaller than the source data that they represent. 3. Research Elaborations In this paper, we have proposed a technique to encrypt message using key. The text taken from keyboard and is encoded into ASCII equivalent. We also have taken a key with digit or character i.e. alphanumeric. The phrase or message is broken into two sub strings and the algorithm reverses both the sub strings individually. Then the corresponding ASCII key value is taken for each character or digit and added with ASCII value of each sub string character. Figure (c) show the process stated below. Table 1. Process of encryption of text data Key 6 3 A ASCII-8 54 51 65 Value For Key Character Message A ASCII 65 Value For Message Character Broken Message SUB 1 A P Reverse SUB 1 I T

P 80

T 84

T

I

P

A

7 55

5 53

B 66

8 56

9 57

I 73

T 84

U 85

D 68

E 69

U

D

E

D

U

T

68

85

84

SUB 2 T Reverse SUB 2 E

After Reversing, ASCII Value For Message Character: 73

84

80

65

69

(ASCII Value of Key Character + After Reversing ASCII Value of Message Character)%254 54+ 73

51+ 84

65 + 80

55+65

54 + 69

51+ 68

65 + 85

55+ 84

119

150

139

ASCII value of Encrypted character 127

135

145

120

123

4. Advantages of the New Algorithm 1. The Algorithm is very simple in nature. 2. In this Algorithm break and reverse operation would make it more secure. 3. This Algorithm is easy to implement. 4. For a small amount of data this algorithm will work very smoothly.

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Conclusions In this paper, we proposed an algorithm to encrypt the data based on symmetric key encryption technique. The above system is giving very good results. The system can be improved by using variable length key. It also can be improved for to decrypt the message form of data. Keeping this goal in mind, the algorithm has been designed in a quite simple manner but tried to keep its security issue in high level value. REFERENCES [1] Ayushi, ‘A Symmetric Key Cryptographic Algorithm’, International Journal of Computer Applications,(0975-8887) (2010) 1(15): 1-4. [2] S. William in Cryptography and Network Security: Principles and Practice, 2nd edition, Prentice-Hall, (1999), 23-50. [3] D. Salama, A. Minaam, H. M. Abdual-Kader, M. M. Hadhoud ‘Evaluating the Effects of Symmetric Cryptography Algorithms on Power Consumption for Different Data Types’, International Journal of Network Security, (2010) 11(2): 7887. [4] D. Chatterjee, J. Nath, S. Dasgupta, A. Nath, ‘A new Symmetric key Cryptography Algorithm using extended MSA method: DJSA symmetric key algorithm’, International Conference on Communication Systems and Network Technologies, (2011), E-ISBN- 978-0-7695-4437-3, DOI:10.1109/CSNT.2011.25, 89-94. [5] C. Paar, JanPelzl, Bartpreneel in Understanding Cryptography: A Text book for student and Practitioners, Springer, (2010). [6] M. P. Gharat, D. Motawani, ‘Overview on Symmetric Key Encryption Algorithms’, Int. Journal of Engineering Research and Applications, (2014) 4(9): 123-126 [7] T. N. Shankar, G. Sahoo, ‘Cryptography by Karatsuba Multiplier with ASCII Codes’, International journal on computer applications, (2010) 1(12): 53-60. [8] B. Forouzan in Cryptography and Network Security, 4th edition, Mc Graw Hill Inc., (2007) [9] A. Kahate in Computer and Network security, 2nd edition , Tata Mc Graw Hill, (2008) [10] S. Saigal, Saloni, A. Sharma, “A Secret Key Cryptographic Algorithm”, Journal of computing, (2011) 3(8), 25-29. [11] Z. H. Sarker, Md. S. Parvez, "A Cost Effective Symmetric Key cryptographic Algorithm for Small Amount of Data”, IEEE Xplore, (1995), http://www.sreemallatech.in/downloads/NET%20PROJECT.pdf.

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