Biblio

An emerging widely used technology cloud computing which a paddle of computing resources is available for the users. Through the internet-based the resources could be supplied to cloud consumers at their request but it is not directly active management by the user. This application-based software infrastructure can store data on remote serves, which can be accessed through the internet and a user who wants to access data stored in the cloud have to use an internet browser or cloud computing software. Data protection has become one of the significant issues in cloud computing when users must rely on their cloud providers for security purposes. In this article, a system that can embarrass the disclosure of the key for distributing a file that will assure security dispensing asymmetric key and sharing it among the cloud environment and user perform the integrity check themselves rather than using third-party services by using compression or hash function where the hash is created using a hash function and it was not mentioned in the previous paper. After the user receives the data every hash is compared with other hash values to check the differences of the data. The time-consumption of encryption and decryption of the data is calculated and compared with the previous paper and the experiment shows that our calculation took around 80% less time.

Lin et al.'s scheme is a hash function Message Authentication Codes (MAC) block cipher based scheme that's composed of the compression function. Fixed point messages have been found on SMALLPRESENT-[s] algorithm. The vulnerability of block cipher algorithm against fixed point attacks can affect the vulnerability of block cipher based hash function schemes. This paper applies fixed point attack against Lin et al.'s modified scheme based on SMALLPRESENT-[8] algorithm. Fixed point attack was done using fixed point message from SMALLPRESENT-[8] algorithm which used as Initial Value (IV) on the scheme branch. The attack result shows that eight fixed point messages are successfully discovered on the B1 branch. The fixed point messages discovery on B1 and B2 branches form 18 fixed point messages on Lin et al.'s modified scheme with different IVs and keys. The discovery of fixed point messages shows that Lin et al.'s modified scheme is vulnerable to fixed point attack.

Cryptographic hash functions are used to protect the integrity of information. Hash functions are designed by using existing block ciphers as compression functions. This is due to challenges and difficulties that are encountered in constructing new hash functions from the scratch. However, the key generations for encryption process result to huge computational cost which affects the efficiency of the hash function. This paper proposes a new, secure and efficient compression function based on a pseudorandom function, that takes in two 2n-bits inputs and produce one n-bit output (2n-to-n bit). In addition, a new keyed hash function with three variants is proposed (PinTar 128 bits, 256 bits and 512 bits) which uses the proposed compression as its underlying building block. Statistical analysis shows that the compression function is an efficient one way random function. Similarly, statistical analysis of the keyed hash function shows that the proposed keyed function has strong avalanche property and is resistant to key exhaustive search attack. The proposed key hash function can be used as candidate for developing security systems.