User talk:Athiranambiar25/sandbox

CP-ABE
CP-ABE is and extension of abe technique.A simple Attribute Based Encryption is dependent on attributes.In ABE, the encrypted data or cipher text are dependent on attributes.There is no concept of access policy in ABE. There are two variations of ABE techniques.They are KP-ABE, and CP-ABE. The former one,Key Policy Attribute Based Encryption (KP-ABE) works as follows:In KP-ABE,the encrypted messages are dependent on attributes and the user's private key has access policy defined on it.KP-ABE provides security and access policy but the drawbacks are that the decryptor cannot choose who can decrypt the text and the data owner has to trust the key issuer.Since K-ABE is not used in the real environment, it's not widely adopted. Looking on to CP-ABE, CP-ABE works reverse to that of CP-ABE.In CP-ABE,the encrypted data or cipher text are dependent on access policy and the user's private key is associated with attributes.Since the encrypted data is dependent on access policy.the encryptor can choose who can decrypt the data. CP-ABE supports collusion resistance.The access policy defined in the encrypted message is a access tree like structure whose non leaf nodes represent the threshold gates like AND,OR and leaf nodes represent the attributes[1]. An cipher text-policy attribute based encryption scheme consists of four fundamental algorithms: Setup, Encrypt, KeyGen, and Decrypt. Setup. The setup algorithm takes no input other than the implicit security parameter. It outputs the public parameters PK and a master key MK. Encrypt(PK,M, A). The encryption algorithm takes as input the public parameters PK, a message M, and an access structure A over the universe of attributes. The algorithm will encrypt M and produce a cipher text CT such that only a user that possesses a set of attributes that satisfies the access structure will be able to decrypt the message. We will assume that the cipher text implicitly contains A. Key Generation(MK,S). The key generation algorithm takes as input the master key MK and a set of attributes S that describe the key. It outputs a private key SK. Decrypt(PK, CT, SK). The decryption algorithm takes as input the public parameters PK, a cipher text CT, which contains an access policy A, and a private key SK, which is a private key for a set S of attributes. If the set S of attributes satisfies the access structure A then the algorithm will decrypt the cipher text and return a message M. Ciphertext-Policy Attribute Based Encryption allows for a new type of encrypted access control where user’s private keys are specified by a set of attributes and a party encrypting data can specify a policy over these attributes specifying which users are able to decrypt. Our system allows policies to be expressed as any monotonic tree access structure and is resistant to collusion attacks in which an attacker might obtain multiple private keys. Athiranambiar25 (talk) 16:58, 18 November 2017 (UTC)