1. Introduction

Cryptography is an effective way of protecting sensitive information transmitted through computer networks[1]. It is an art of hiding information by encoding it into unreadable formats. The main goal of cryptosystem is to prevent un-authorized access of information by adopting non- breakable algorithms[2,5]. The information can only be revealed if the attacker has enough time, desire and resources. Thus the cryptosystem makes obtaining the information too work insensitive to be worth it to the attacker. The analytical criteria's of the cryptography is confidentiality, data integrity, authentication and non-repudiation[3,8].

Confidentiality is the feature of secrecy made for the information. It ensures that any un-authorized parties cannot access the information. It also guaranties for physical and logical protection of data[4].

Data integrity provide assurance from manipulation during transmission, accidentally or intentionally[7].

Authentication is related with validity of identified parties entering into a communication[6]. Non-repudiation ensures that sender and receiver cannot deny from their actions[5,11]. This procedure protect from denial of the activities made by sender or receiver.

Cryptography has a long and fascinating history proliferation of computers and communication system has brought it with a demand to protect information in "digital age"[9]. Such algorithms are called ciphers. In this paper we have done the analytical survey of the block ciphers and stream ciphers. Further a report on competitive performance has been layout for both the symmetric and asymmetric cryptographic systems[10].

2. Organization

In section 3, if have depicted the basics of cryptography. The task of en-cipher and de-cipher has been introduced.

In section 4, we have analyzed the survey result of the various cipher models symmetric, as well as asymmetric consisting block and stream ciphers both.

Finally in section 5, we have presented our views and the conclusion for the performance evaluation of the cipher models.

3. Basics of Cryptography

Figure 3.1. Encipher Process.

Figure 3.2. Decipher process.

Figure 3.3. Configuration of a cryptosystem.

Cryptography is the method of conversion of the plaintext (original data) into cipher text (unreadable data). The process of encryption transforms plain text into cipher text whether the process of decryption transforms cipher text into plain text.

The cryptographic systems work on two mode i.e. bit by bit mode which is called stream cipher and another where a group of character by a char mode which is called block cipher[15,18].

In block cipher algorithms, message is divided into blocks and mathematical functions are performed (like substitution, transposition, transformation) to encrypt and decrypt these blocks[13,14].

Stream cipher encrypts and decrypts data on bit or byte at a time. It is most suitable for chip level or hardware implementations[12,16].

Figure 3.4. Model of a block cipher.

Figure 3.5. Model of a Stream Cipher.

4. Survey on Cryptographic System

A cryptographic system recognized by its way of performing encryption/decryption. Modern cryptographic systems are classified as symmetric and asymmetric cryptosystem[17]. A symmetric cryptosystem use the same key to encrypt and decrypt the message, whether in asymmetric cryptosystem encryption and decryption is by using public and private key[18,20,21].

Following table enumerates the difference characteristics between symmetric as asymmetric system.

4.1. Symmetric Cryptosystems

It is the mechanism of cryptography based on only single key called "secret key" for encryption and decryption[19,23].

We are analyzing the following symmetric block cipher algorithms[24,25].

Ÿ MARS : Developed by the IBM team who have developed DES and Lucipher in 1974.

Ÿ RC6 : Recent code 6 developed by RSA laboratory.

Ÿ Serpent : It is developed by Ross Anderson Eli Biham and Lars Knudsen.

Ÿ Twofish : Developed by counterpane systems.

Ÿ Rijndael : Developed by Joan Daemon and Vincent Rijmen.

We can conclude the superiority of Rijndael algorithm in the comparative analysis of various symmetric block ciphers.

Following are the tables to demonstrate the performance of ciphers.

Table 4.11. Encryption/Decryption performance. 32 bit (C) 32 bit Java 64 bit C and Assembly 8 bit C and Assembly MARS ++ ++ ++ ++ RC6 +++ +++ ++ ++ RIJNDAEL ++ ++ +++ +++ SERPENT + + + + TWOFISH ++ + ++ ++

Table 4.12. Key Setup performance. 32 bit (C) 32 bit Java 64 bit C and Assembly 8 bit C and Assembly MARS ++ ++ + ++ RC6 ++ ++ ++ + RIJNDAEL +++ +++ +++ +++ SERPENT + ++ ++ + TWOFISH + + + ++

4.2. Asymmetric Cryptosystem

In this cryptosystem different key is used to encrypt a message than the key that is used to decrypt the message.

We are analyzing the following asymmetric cryptosystem[24,28].

Ÿ RSA : It is invented by Ron Rivest, Adi Shamir and Leonard Adleman.

Ÿ ECC : Elliptic curve cryptosystem is useful for limited source devices.

Ÿ ECRYPT : A Prominent cryptosystem like RSA.

Ÿ HASH : A mathematical function based cryptosystem.

Ÿ DSAsg : Cryptosystem used in designing digital signatures and certificates.

Following table depicts the key length comparison for the security of various asymmetric cryptosystem over time of development in digital era[26,27].

Table 4.21. Key length Vs Security. Year Encrypt HASH RSA DSAsg ECC 2002 72 144 1028 127 135 2005 74 148 1149 131 139 2010 78 156 1369 138 146 2015 82 164 1613 145 154 2020 86 172 1882 151 160

5. Conclusions

Among the various models of symmetric cipher analyzed the Rijndael is the best. Actually it is the role model of DES and AES. This model is adopted by different information security agencies like NSA, NIST and FIPS[30].

Among the various asymmetric cipher RSA is a moderate and most useful cipher for small data encryption like digital signature, ATM Pin etc.[24].

But RSA is much slower than Rijndael and other symmetric cipher[14].

The symmetric cipher like Rijndael is support to be secure against mathematical attacks until 2090[15]. Thus they are very suitable for hardware level security in communicating devices.