A Comparative Study of different attribute based encyrption models for cloud data security

With the rapid development of the distributedcomputing and internet architectures, there is an exponential demand for data processing and sharing resources in the cloud environment. The third-party provider needs to implement trusted access control and confidentiality for the cloud customers. Also, it is highly recommendable for the large scale applications to support one to many communications to reduce the data encryption and decryption mode. Ensuring the security and access of the cloud data is a major issue, as users often store their sensitive data with the third party authorities, but these TPA may be interested. The access control mechanism ensures that trusted clients are able to access data and unauthorized clients are not able to access data from the remote cloud server. Most of the client’s data stored in the remote cloud server are highly sensitive and need to secure against third party authorities and unauthorized users. In this paper, traditionally, Attribute based encryption and decryption such as CP-ABE, KP-ABE,HPABE, Homomorphic ABE approaches are studied with different security parameters. Also, an analysis of the different attribute based encryption techniques along with limitations and security challenges are discussed. Keywords— ABE, Cloud security, Encryption andDecryption Algorithm I.INTRODUCTION To protect the data and privacy from disclosure, a number of schemes have been proposed for data access control in cloud computing. Before applying an access control scheme in a practical system, it is indispensable to evaluate its performance in various aspects, such as efficiency and flexibility. The cloud service providers adopted various methodologies to provide a more secure and trust worthy environment for their customers. They prefer to encrypt customer’s sensitive data before uploading it to cloud. The prime goal of attribute-based encryption model is to provide security and access control. They identified users’ attributes as the main component and used in both secret key as well as in cipher text. When the attributes of secret key and cipher text are identical as threshold d, decryption occurs. Another significant feature of ABE is collision resistance. The only flaw of this scheme is users’ public keys are required by the data owner in encryption. This drawback forbids the implementation of this model in real environment due to involvement of monotonic attributes. The traditional cryptosystem framework based on public key infrastructure (PKI) can achieve data security, confidentiality and non-repudiation along with limitations. In order to encrypt data, the third party provider needs to obtain the authorized user’s public keys and then communicate the cipher data to the individual authorized user, which increases the bandwidth and processing overhead[1-4]. Third party cloud servers are vulnerable to different type of message integrity attacks[1-4]. Sahai and waters proposed a fuzzy Identity based encryption scheme in which a descriptive attributes set are considered as identity for encryption and decryption process. For the privacy or secret key kAS corresponds to the attribute set S. We can decrypt the data using k AS ' corresponds to the attribute set s ' and satisfies the condition |SS ' |d ,where d is the minimum number of attributes. With the immense growth of cloud services, data servers are needed to be trusted as well as safe enough in order to store much confidential sensitive information. Numbers of algorithms involving various access control schemes are developed to achieve data ISSN: 2231-5373 http://www.ijmttjournal. org Page 113 International Journal of Mathematics Trends and Technology (IJMTT) – Volume 51 Number 2 November 2017 security in cloud. But with the rapid growth of technology, now-a-days data are stored in distributed cloud servers. Distributed cloud servers are data servers responsible for storing data in different servers which is by default exposed to other data owners. Some frequently used symmetric cryptographic algorithms are AES, DES, IDEA, TDES, Blowfish and RC6. RSA and ECC can be categorized under asymmetric cryptographic algorithms. Symmetric cryptographic algorithms generally consider a common key both for the process of encryption and decryption. But, the asymmetric cryptographic algorithm uses separate keys for encryption and decryption. Here, a public key is considered for encryption and a private key is used for decryption. The initial or first tier of security is formed by implementing digital signature scheme[5]. Cloud computing environment in mostly insecure, as it is used worldwide. All the data are needed to be encrypted prior to uploading it on cloud. Several classical public key encryption approaches can be implemented to enhance security, but it also gives rise to some issues which are mentioned below 1. For the encryption process to be executed, data owners require user’s public key. 2. The storage overhead is increased, as for a single plain text there exist many public keys. 3. In order to resolve the above issues, Sahai and Waters introduced a new technique and named it as attribute-based encryption (ABE) technique in the year 2005. At first they developed the basic algorithm of attribute based encryption which is modified and extended by various different models in the subsequent period of time [5]. In the above approach, users’ identity is considered as attributes and set of attributes are used together to encrypt and decrypt data. Attribute based encryption (ABE) The main objective of the ABE is to provide better security and access control mechanism. ABE can be stated as a special type of public key encryption method which is responsible for encryption and decryption according to the attribute values. In the above approach, both the secret key and cipher text depends on attributes. The cipher text is decrypted by decryption algorithm, when attributes of user keys matches attributes of cipher text. If the number of matching is equivalent with the minimum threshold d, the decryption algorithm is executed successfully. Key Policy Attribute Based Encryption(KP-ABE) The traditional attribute based encryption technique is modified and extended in order to overcome the above issues. Every individual user is associated with an access tree structure. Threshold gates represent the nodes of access trees, whereas attribute values are assigned to leaf nodes. User’s secret key has the responsibility of representing access tree structure. Cipher text includes set of attributes and the secret keys are merged with monotonic access structures in order to choose the particular cipher text which is meant for that user to decrypt[6-7]. Chaos based hash functions have gained a lot of attraction by the researchers in the field of cloud computing and mobile computing. Due to the limited computing power, chaotic orbits will become nonperiodic. Most of the traditional chaos based hash functions are processed in sequential model, which restricts their execution speed and performance on the mobile computing. In [8] a parallel keyed hash function using the chaos-based algorithm is proposed. The limitations in the parallel chaos model were presented in [9]. Various experimental results have been performedon arbitrary messages and finally concluded that the parallel chaotic hash function is not secured against the statistical attacks. To overcome this problem, complex chaoticbased hashing techniques are developed which are nonlinear, random and dynamic in nature. It can be represented by either discrete or continuous systems. Henon mapping and logistic mapping can be categorized under discrete, whereas Lorenz and Rossler system comes under continuous. This system is highly responsive to initial conditions. Lyapunov exponents are one of the important components of chaotic system which decides whether the given system is chaotic or not. Our proposed scheme involves various logical functions and is developed according to the complex temporal behavior and provides high sensitivity to the initial constraints of the high-dimensional chaotic maps. The main objective of a chaotic-hashing system is the convergence property in the complex chaotic systems. The features responsible for this convergence are:a) Both are deterministic. b) Both are complex and not predictable. c) In chaotic system, a small change in the initial conditions can affect and reflect a huge change in the output. ISSN: 2231-5373 http://www.ijmttjournal. org Page 114 International Journal of Mathematics Trends and Technology (IJMTT) – Volume 51 Number 2 November 2017 I. Related Work Symmetric Key Encryption (SKE): Symmetric Key Encryption is a special cryptographic approach which applies a shared secret key for both the process of encryption and decryption. The key which is used for encryption is also considered for the process of decryption. Therefore, both the sender and receiver must have the same shared secret key. The sharing of secret key can become a major disadvantage of encryption scheme. If an unauthorized user gets access to this key, then the cloud data can be compromised[78-81]. Public Key Encryption (PKE): In the process of Public Key Encryption, two different keys are used for encryption and decryption process. Among two of these keys, one key is public and the other one is private. The public key is distributed publicly and the private key is only available to the receiver. All messages are encrypted with receiver’s public key and the process of decryption is carried out by the private key. The conventional attribute based encryption approach is modified and extended in the subsequent time. Two other techniques are developed such as, Cipher-text Policy Attribute Based Encryption (CP-ABE) and the Key Policy Attribute Based Encryption (KP-ABE). CPABE and KP-ABE are two extended versions of traditional ABE scheme. Also, summarized key management models with different cloud properties a