Equivalent to des encryption using a single key recall that, for example, the caesar cipher is a group if a message were encrypted with the caesar cipher with a key of 3 and then re-encrypted with the caesar cipher with a key of 5, the result is equivalent to encrypting the message with the caesar cipher with a key of 8. Full-text paper (pdf): a secure re-encryption scheme for data sharing in unreliable cloud environment.
Secure re-encryption scheme in untrusted cloud it is a time based re-encryption scheme, which allows each cloud server to automatically re-encryption data based on its internal clock the basic idea of secure re-encryption scheme in untrusted cloud scheme is to associate the data with an access control and an access time.
At  the encryption and re-encryption is done using abe technique in this paper we have used instant mailing scheme for instant password ivconclusion and future enhancement the proposed r3 scheme, a new method for managing access control based on the cloud server’s internal clock. Keys proxy re-encryption enables this in a not-terribly-ineﬃcient way 1 first, encrypt the ﬁlesystem using a fast symmetric key cryptosystem such as aes a separate session key is used for each ﬁle 2 group manager alice then encrypts all of the ﬁle session keys under her proxy re-encryption public key pk a 3. The delay of issuing the pre keys may cause potential security risks in this paper, we propose a time-based proxy re-encryption (timepre) scheme to allow a user's access right to expire automatically after a predetermined period of time in this case, the data owner can be offline in the process of user revocations.
With the prevalence of internet access, document storage has become a fundamental web service in recent years one important topic is how to design a secure channel for efficiently sharing documents with another receiver in this paper, we demonstrate a re-encryption method that is designed with row complete matrices with this new method, the document owner can share a ciphertext in the cloud. Attribute based re-encryption  and time based encryption  provide better method for data sharing in cloud there is a necessity of accountability of the sensitive data.
In this method automatic re-encryption of data will takes place based on the internal clock value present at the cloud server to execute this automatic reencryption we will make use of encryption technique called attribute based - encryption (abe) with des (data encryption standard. A study of secure and efficient data sharing scheme for cloud storage architecture re-encryption key changing a’s crypt to b’s crypt proxy re-encryption function and searchable encryption function this method provides efficiency in terms of calculation volume. Data encryption standard (des): des (data encryption standard) algorithm purpose is to provide a standard method for protecting sensitive commercial and unclassified data it is scalable algorithm due to varying the key size and block size the data encryption standard is one of the most common used encryption mechanisms.