International Journal of Computer Engineering and Applications, Volume XII, Special Issue, April 18, www.ijcea.com ISSN 2321-3469 CRYPTOGRAPHIC BLOCK CIPHER ALGORITHMS Anil Gopal Sawant Dr. Vilas N. Nitnaware Research Scholar, Ph.D. Student Principal JJT University, Rajasthan, India D. Y. Patil School of Engineering Academy, Pune [email protected] [email protected] Abstract — Today, billions of people all over the world parameters and compared them to choose the best data communicate by various ways including electronic networks, encryption algorithm so that we can be used in future work. such as e-mail, Social network, ATMs, e-commerce or mobile phones. Also now a day’s, world research is happening in Keywords— Cryptography, Internet of things, Digitization, Block artificial intelligence and Internet of things makes electronic cipher. devices are increasingly connected with each other and also interact with each other which creates huge data. The rapid I. INTRODUCTION increase of Digitization resulted to an increased reliance Cryptography is a technique of protecting secure on cryptography. Modern era has seen the rise of computing information from unwanted individuals by converting it into devices, especially hand held devices. Information, in large unintelligible form. It is an art to transform or change the quantity, can be digitalized and stored on these devices. Also data to make it secure and immune against security attacks. these information must be shared to others devices, connected either via wired or wireless links, which are insecure channels. Cryptography[1,2] is used for secure Information is a long term resource to any individual and/or communication of the electronic channel in the presence of organization and hence privacy of the information is of great third parties to secured the data with respect to importance. Cryptographyis a way to ensure the authentication, confidentiality, authentication, data integrity, access control integrity, accessibility, confidentiality, and identity of user data and non-repudiation. An original message is known as the and also maintained the security and privacy of user data. plaintext, while the encrypted message is called the cipher- Encryption is the process of converting normal data or plaintext text[18]. The way of transforming from plaintext to cipher- to something incomprehensible or cipher-text by applying text is known as enciphering or encryption[18, 19] and again mathematical transformations or formulae. These mathematical restoring the plaintext from the cipher-text is deciphering or transformations or formulae used for encryption processes are called algorithms. We have analysed data encryption algorithms decryption[25]. DES, Triple DES, AES, IDEA, RC5, TWOFISH, THREEFISH and BLOWFISH etc. All These Block Cipher Algorithms are symmetric key cryptographic algorithms. In this paper, we have analysed various encryption algorithms on the basis of different 1 CRYPTOGRAPHIC BLOCK CIPHER ALGORITHMS Access Control :Only authorised users can access the data. This is done to avoid unauthorized user access. A key is used at the time of encryption and decryption process. The security level of cryptography is determined by key length[18]. II. OVERVIEW OF VARIOUS ALGORITHMS In this section we will discuss about various cryptographic algorithms to be analysed for their performance evaluation[15]. To start the algorithm analysis firstly we should know that what is Algorithm actually. “An algorithm is a sequence of unambiguous instructions for solving a problem”, i.e., for obtaining a required output for Figure 1. Process of Cryptography any legitimate input in a finite amount of time. We are taking The many schemes used for encryption constitute the area eight encryption algorithms under consideration those are Basic terminologies in cryptography are as follows: DES, Triple DES, AES, IDEA, RC5, TWOFISH, THREEFISH and This terminology is very important to understand because in BLOWFISH [18] etc. every algorithm description, we are going to discuss these common terms: A. DES (Data Encryption Standard) Plain-text: The original text or message used in It was developed in the early 1975 at IBM labs by communication in called as Plain text[20]. Example: John Horst Fiestel. The DES was approved by the NBS (National sends “Hello” to Perry. Here “Hello” is Plain text or Original Bureau of Standards, now called NIST (National Institute of message. The original message to be encrypted. Standards and Technology) in 1978. The DES was Encryption: Encryption is a process of converting Plain text standardized by the ANSI (American National Standard into Cipher text. This non-readable message can securely be Institute) under the name of ANSI X3.92, better known as communicated over the unsecure network. Encryption DEA (Data Encryption Algorithm)[4]. The DES was once a process is done using encryption algorithm. The process of predominant symmetric-key algorithm[6] for the encryption mapping the original data to a meaningless form. of electronic data. DES uses 56 bits key for encryption and Key: A key is a numeric or Alpha-numeric text decryption. It completes the 16 rounds of encryption on each (mathematical formula). In encryption process it takes place 64 bits block of data. Data encryption standard works on a on Plain text and in decryption process it takes place on particular principle. Data encryption standard is a symmetric cipher text. The confidential key is the input to encryption encryption[9] system that uses 64-bit blocks, 8 bits (one algorithm. The algorithm in turn produces different outputs octet) of which are used for parity checks (to verify the key's for different keys used[19]. integrity)[25]. Each of the key's parity bits (1 every 8 bits) is Cipher-text: The plain text is encrypted in un-readable used to check one of the key's octets by odd parity, that is, message. This message has no meaning is called Cipher Text. each of the parity bits is adjusted to have an odd number of The meaningless message obtained after encryption process. '1's in the octet it belongs to[14]. DES is now considered to Decryption: The encryption process in reverse order form be insecure for various other applications. This is mainly the decryption process. The output of this decryption process because to the 56-bit key size being too small to provide is the original message. security. But now it is an outdated symmetric key data Key Size: Key size is the length of key which is measure in encryption method[18]. bits, used in different algorithm with different key sizes[26]. Block Size : Key cipher works on fixed length string of bits B. DES (Triple Data Encryption Standard) called Block size. This block size can changes from In cryptography techniques, Triple Data Encryption Standard algorithm to algorithm[15]. (3DES) is the common name for the Triple Data Encryption Round :Round of encryption means that how much time Algorithm (TDEA) symmetric-key block cipher, which encryption function is executed in complete encryption applies the Data Encryption Standard (DES) encryption process till it gives cipher text as output. algorithm three times to each data block. Triple-DES is also proposed by IBM in 1978 as a substitute to DES. So, 3DES is simply the DES symmetric encryption algorithm[19], used A. Main Objectives of Cryptography three times on the same data. Three DES is also called as T- Confidentiality: Only an authorized recipient should be able DES. It uses the simple DES encryption algorithm three to extract the contents of the message from its encrypted times to enhance the security of encrypted text[14]. form. Integrity: The recipient should be able to determine if the message has been altered. Assuming receiver that received message has not been altered in any way from the original message[19]. Authentication: The sender and receiver can confirm each other’s identity and the origin/destination of the information. Non-repudiation: The emitter should not be able to deny sending the message. 2 International Journal of Computer Engineering and Applications, Volume XII, Special Issue, April 18, www.ijcea.com ISSN 2321-3469 Add Round Key: In this step, round key is added to the output of the previous step during the forward encryption process. This step normally differs from others because of various key size. In AES encryption process[23,24], it uses different round keys. These keys are applied along with other mathematical operations on an array of data in this process. This data is present in blocks of particular size. This array is called state array. This encryption process includes following process: Figure 2. 3DES Structure 1. Initially derive the different round keys from cipher key. In this technique, same data is encrypted two times 2. Initialize the state array with block data or plaintext. more using DES. This makes the encryption more stronger 3. then Start with initial state array by adding round key. and more difficult to break and hence three times secured. 4. Perform the process of state manipulation in nine rounds. Triple DES is basically a Block cipher which uses generally 5. After tenth round of manipulation, we will get the final 48 rounds i.e. Three times the DES in its computation, and output as cipher text. By following above process we get the also key length of 168 bits. 3-DES also Uses the Block size final encrypted text or cipher text. of 64 bits for encryption[14]. The main advantage of Triple DES is that it is three times secure (as it is combination or D. Blowfish three DES algorithms with different keys at each level) than Blowfish was developed by bruce schneier in 1993. It is DES that’s why it is preferred over simple DES encryption basically a symmetric block cipher algorithm having variable algorithm. It provide adequate security to the data but it is not length key from 32 bits to 448 bits in sizes.