Automated Attribute-Based Solution Cryptographic Credentials For Scalable Access Control InCloud ComputingLiterature surveyData security and access control is one of the most challenging ongoing research work in cloud computing, because of users outsourcing their sensitive data to cloud providers. Existing solutions that use pure cryptographic techniques to mitigate these security and access control problems suffer from heavy computational overhead on the data owner as well as the cloud service provider for key distribution and management.Problems of access control in cloud computing includes the mechanism to distribute decryption key,number of users may become large and solution is not efficient.[6]In distributed systems users need to share sensitive objects with others basedon the recipients ability to satisfy a policy. Attribute-Based Encryption (ABE)[3]is paradigm where such policies are specified and cryptographically enforcedin the encryption algorithm itself.the drawbacks include the threshold lacksexpressibility,flexibility.Both ciphertext and decryption keys are associated with set of attributes.[3]Ciphertext-Policy ABE (CP-ABE)[1] is a form ofABE where policies are associated with encrypted data and attributes are associatedwith keys. User attributes are represented in keys. The advantage includes the user who can see the message content can decrypt in absence of group keys,It save the cost to distribute group keys.This scheme suffered with the major drawback of lacking in updating efficiency,if any changes made to the attribute the private key associated with the attribute should also be changed.[1]CP-ASBE a new form of CP-ABE which, unlike existingCP-ABE schemes that represent user attributes as a monolithic set in keys, organizesuser attributes into a recursive set based structure and allows users to imposedynamic constraints on how those attributes may be combined to satisfy a policy. Specifically CP-ASBE allows user attributes to be organized into a recursive family of sets and policies that can selectively restrict decrypting users to use attributes from within a single set or allow them to combine attributes from multiple sets. Thus by grouping user attributes into sets such that those belonging to a single set have no restrictions on how they can be combined.Key Policy Attribute Based Encryption(KP-ABE)[1],Cipher text is associated with set of attributes where the decryption key is associated with tree access structure. interior nodes of the access tree are threshold gates and leaf nodes are associated with attributes. User secret key is definedto reflect the access structure so that the user is able to decrypta ciphertext if and only if the data attributes satisfy his accessstructure.A KP-ABE scheme is composed of four algorithmsSetup:This algorithm takes as input a security parameter and the attribute universe U = {1, 2, . . . ,N} of cardinalityN. It defines a bilinear group G1 of prime order p with agenerator g,a bilinear map e : G1 G1 ! G2 which has theproperties of bilinearity, computability, and non-degeneracy.It returns the public key PK as well as a system master key.MK as followsPK = (Y, T1, T2, . . . , TN)MK = (y, t1, t2, . . . ,tN) While PK is publicly known toall the parties in the system, MK is kept as a secret by theauthority party.Encryption:This algorithm takes a message M, the public keyPK, and a set of attributes I as input. It outputs the ciphertextKey Generation:This algorithm takes as input an access treeT, the master key MK, and the public key PK. It outputsa user secret key SK as follows. Then it outputs SK as follows.SK = {ski}i2Lwhere L denotes the set of attributes attached to the leafnodes of T and ski = gpi(0)ti .Decryption:This algorithm takes as input the ciphertext Eencrypted under the attribute set I, the users secret keySK for access tree T, and the public key PK. It first computes e(Ei, ski) = e(g,g)pi(0)s for leaf nodes. Then, itaggregates these pairing results in the bottom-up manner usingthe polynomial interpolation technique. Finally, it may recoverthe blind factor Y s = e(g, g)ysand output the message M ifand only if I satisfies T. This is an enhanced KP-ABE scheme which supports usersecret key accountability.[2]Fuzzy Identity Based Encryption From Lattices[3],Inconstructing a Fuzzy IdentityBased Encryption (Fuzzy IBE) scheme based on lattices. A fuzzy IBE scheme is exactly like anidentity-based encryption scheme except that ciphertext encrypted under an identity idenc can be decrypted using the secret key correspondingto any identity iddecthat is close enough" to idenc. Examples arise when using one's biometric information as the identity, but also in general access control systems that permit access as long asthe user satisfies a certain number of conditions.Theconstruction is secure in the selective security model under the learning with errors (LWE) secure under the worst-case hardness of shortvector problems" on arbitrary lattices. Extended the construction to handle large universes,and to resist chosen ciphertext (CCA) attacks. [3]Identity Based Encryption(IBE) is an important primitive ofID-based cryptography. As such it is a type ofpublic-key encryptionin which thepublic key of a user is some unique information about the identity of the user (e.g. a user's email address). This can use the text-value of the name or domain name as a key or the physical IP address it translates to. The first implementation of an email-address based PKI was developed byAdi Shamirin 1984which allowed users to verifydigital signaturesusing only public information such as the user's identifier.He was however only able to give an instantiation ofidentity-based signatures. It includes the major advantages of any identity-based encryption scheme is that if there are only a finite number of users, after all users have been issued with keys the third party's secret can be destroyed. This can take place because this system assumes that, once issued, keys are always valid .The obtained drawback is if a Private Key Generator (PKG)[7] is compromised, all messages protected over the entire lifetime of the public-private key pair used by that server are also compromised. This introduces a key-management problem where all users must have the most recent public key for the server.Because the Private Key Generator (PKG) generates private keys for users, it may decrypt and/or sign any message without authorisation. This implies that IBE systems cannot be used fornon-repudiation IBE solutions may rely on cryptographic techniques that are insecure against code breakingquantum computerattacks.Hierarchical Identity Based Encryption (HIBE)[5] system where the ciphertext consists of just three group elements and decryption requires only two bilinear map computations,regardless of the hierarchy depth. Encryption is as ecient as in other HIBE systems.The scheme is selective-ID secure in the standard model and fully secure in the random oracle model. This system has a number of applications, it gives very ecient forward secure public key and identity based cryptosystems , it converts the NNL broadcast encryption system into an ecient public key broadcast system, and it provides an ecient mechanism for encrypting to the future. The system also supports limited delegation where users can be given restricted private keys that only allow delegation to bounded depth.The HIBE system can be modied to support sublinear size private keys at the cost of some ciphertext expansion.[5]In Hierarchical Attribute Based Encryption[4] to keep the shared data confidential against untrusted cloud service providers (CSPs), a natural way is to store only the encrypted data in a cloud. The key problems of this approach include establishing access control for the encrypted data, and revoking the access rights from users when they are no longer authorized to access the encrypted data. This approach solves both problems.[8]The hierarchical attribute-based encryption scheme (HABE) is introduced by combining a hierarchical identity-based encryption (HIBE) system and a ciphertext-policy attribute-based encryption (CP-ABE) system, so as to provide not only fine-grained access control, but also full delegation and high performance.It provides the scalable revocation scheme by applying proxy re-encryption (PRE) and lazy re-encryption (LRE) to the HABE scheme, so as to efficiently revoke access rights from users.[4]`REFERENCES[1]S. Yu, C. Wang, K. Ren, and W. Lou. Achieving Secure, Scalable, and Fine-grained Data Access Control in Cloud Computing. In Proceedings of IEEE INFOCOM 2010, pages 534-542.[2] G.Wang, Q. Liu, and J.Wu, Hierachicalattibute-based encryption forfine-grained access control in cloud storage services, in Proc. ACMConf. Computer and Communications Security (ACM CCS), Chicago,IL, 2010.[3]S. Yu, C. Wang, K. Ren, and W. Lou, Achiving secure, scalable, and fine-grained data access control in cloud computing, in Proc. IEEEINFOCOM 2010, 2010, pp. 534542.

[4]R. Bobba, H. Khurana, and M. Prabhakaran, Attribute-sets: A practicallymotivated enhancement to attribute-based encryption, in Proc.ESORICS, Saint Malo, France, 2009. [5] A. Sahai and B. Waters, Fuzzy identity based encryption, in Proc.Acvances in CryptologyEurocrypt, 2005, vol. 3494, LNCS, pp.457473 [6] Dan Boneh,XavierBoyen and Eu-Jin Goh,Hierarchical Identity Based Encryption with Constant Size Ciphertext, , in Proc.Acvances in CryptologyEurocrypt, 2005, vol. 3494, LNCS, pp.723-762[7]J. Li, N Li, and W. H. Winsborough, Automated trust negotiation using cryptographic credentials, in Proc. ACM Conf. Computer andCommunications Security (CCS), Alexandria, VA, 2005.[8]T. Yu and M. Winslett, A unified scheme for resource protection inautomated trust negotiation, in Proc. IEEE Symp. Security and Privacy,Berkeley, CA, 2003.