Abstract: A method for generating a key stream according to an embodiment includes generating r round keys that are each N-dimensional integer vectors including elements of an integer set defined based on a prime number t, based on a random bit string, an encryption counter, and a secret key that is an N-dimensional integer vector consisting of elements of the integer set , generating a first round output vector x1 by performing a modular addition operation on an initial vector and a first round key RK1 of the r round keys with the prime number t as a modulus, and generating a key stream that is an N-dimensional integer vector consisting of elements of the integer set from the first round output vector x1 by using a second to r-th round keys of the r round keys, and one or more first round functions and a second round function.

Abstract: The present invention relates to a catalyst for hydrogenation of an aromatic compound, which is capable of greatly reducing the inactivation of a catalyst by using a support including a magnesium-based spinel structure, and a preparation method therefor.

Abstract: A synchronization method and apparatus for synchronizing data at synchronization intervals configured individually for respective data objects in a portable terminal is provided. The synchronization method includes configuring respective synchronization intervals of a plurality of data objects, and synchronizing the data objects the respective synchronization intervals. The data synchronization method and apparatus allows for setting of respective synchronization intervals to a first value for the data that are changed frequently and a second value for the data that are not changed frequently. Also, the data synchronization method and apparatus is capable of configuring the synchronization intervals of the data objects according to properties of the data objects so as to reduce unnecessary data synchronization attempts.