-word (64-bit) input (plaintext) and output (ciphertext) block sizes. RC5 uses an \expanded key table, " S, derived from the user's supplied secret key. The size t of table S depends on the number r of rounds: S has t =2(r +1) words. There are thus several distinct \RC5 " algorithms

This paper introduces a new adaptive chosen ciphertext attack against certain protocols based on RSA. We show that an RSA private-key operation can be performed if the attacker has access to an oracle that, for any chosen ciphertext, returns only one bit telling whether the ciphertext corresponds

Abstract Current research literature for protecting mobile agents from malicious execution environments, such as homomorphic encryption schemes, Boolean circuits, obfuscation and computing with encrypted functions, provide building blocks for the possibility of secure remote encrypted computations

Cloud storage is an online data storage and it is located as centrally.Cloud data ownerprovidethe facility for users to online store their data and access from any location. Though it has reliable for the user to achieve a secure and dependent cloud storage service. Ina key aggregate crypto-systemkey is generated fordifferent attributes of data in different cipher text classes and its associated keys. It derived aggregate key on the basis of attribute and identitywhich, depending on the different classes according to cloud data owner. By using this technique aunique cryptographic key achieves. It is optimallysecure for cloud data and privacy preserving key generating process.The cloud data ownerdecidesthe access levelof the data, such as public, private and hierarchyaccess level in order toenhance the data access capability in a data sharing cloud mechanism.Blowfish is thebest data security algorithm. It is higher security and faster execution as compared toother cryptographic algorithms. The blowfish algorithmis a secure for storing data in the cloud.It is an effective derivation of secret key generation and key management.

A new secret-key block cipher is proposed as a candidate for a new encryption standard. In the proposed cipher, the plaintext and the ciphertext are 64 bit blocks, while the secret key is 128 bit long. The cipher is based on the design concept of "mixing operations from different algebraic

of the above definition. This gives the first mode provably secure against chosen ciphertext attacks. Although RPC is slightly less efficient than, say, CBC mode (requiring about 33 % more block cipher applications and having ciphertext expansion of the same amount when using a block cipher with 128-bit

We describe a parallelizable block-cipher mode of operation that simultaneously provides privacy and authenticity. OCB encrypts-and-authenticates a nonempty string M # {0, 1} # using #|M |/n# + 2 block-cipher invocations, where n is the block length of the underlying block cipher. Additional

One of the important aspects of the security of block ciphers is the randomness of the cipher text. One criterion used to evaluate the Advanced Encryption Standard (AES) candidate algorithms was their demonstrated suitability as random number generators. In this paper, we introduced a new approach

We propose a generalisation of Paillier’s probabilistic public key system, in which the expansion factor is reduced and which allows to adjust the block length of the scheme even after the public key has been fixed, without loosing the homomorphic property.We show that the generalisation

Abstract. We present a method for efficient conversion of differential (chosen plaintext) attacks into the more practical known plaintext and ciphertext-only attacks. Our observation may save up to a factor of 2 20 in data over the known methods, assuming that plaintext is ASCII encoded English (or