Abstract: Provided is an apparatus and a method of restricting an access to an application module of a mobile wireless device. The apparatus for restricting an access to an application module of a mobile wireless device according to an exemplary embodiment of the present invention includes an access restriction unit for receiving a request for an access to an application module from a basic module, and for restricting the access of the basic module to the application module when a restriction on the access is required. Further included is an access restriction determination unit for determining whether the restriction on the access of the basic module to the application module according to an access environment is required. Also included is an access environment determination unit for monitoring the access environment of the basic module to the application module and for providing the access restriction determination unit with a result of monitoring the access environment.

Abstract: An apparatus and method are provided for reducing time taken for generating a digital signature and generating the digital signature using a minimum number of operations using at least two secret keys. One secret key among at least two secret keys may be set from a value resulting from hashing a message to be transmitted. A number of times for hashing the secret key is determined, and a value resulting from hashing the determined secret key by the determined hashing number of times is set as the digital signature.

Abstract: Provided are a method and an apparatus for generating and validating a digital signature. The apparatus for generating the digital signature includes: a converter converting a message to be transmitted into a codeword having a set length using a Griesmer code; and a digital signature generator allowing each of bits constituting the codeword to correspond to one of a plurality of secret keys constituting a table and combining the corresponding secret keys to generate the digital signature. The apparatus for validating the digital signature includes: a converter converting a received message into a codeword having a set length using a Griesmer code; and a digital signature validator allowing each of bits constituting the codeword to correspond to one of a plurality of public keys constituting a table and validating whether a value obtained by combining the corresponding public keys is equal to a value obtained by hashing the digital signature.

Abstract: A method for assigning conditional access system (CAS) keys to a terminal to thus reduce the number of entitlement management messages (EMMs) required to send contents to a digital broadcast subscriber. To this end, a broadcast center causes transmission of the CAS-related key to limit access to the digital content, over a mobile communication network used for a mobile communication, and causes transmission of the digital content over a digital broadcasting network used for digital broadcasts. Since the CAS-related key is transmitted to the digital broadcast subscriber's terminal over the mobile communication network, it is possible to effectively utilize the frequency bandwidth of the digital broadcasting network for the digital broadcasting. Furthermore, the security of the CAS-related key can be strengthened by sending the CAS-related key to the terminal over the mobile communication network.

Abstract: A data encryption method using a public key includes encoding data into a first code using a first public key, selecting a predetermined error vector, encoding the selected error vector into a second code using a second public key, and generating a ciphertext by adding the first and second codes. A corresponding decryption method includes performing first decoding of the ciphertext using a first set of a plurality of secret keys, determining locations of errors in the result of the first decoding using a second set of the plurality of secret keys and declaring erasures to the locations, performing second decoding according to a predetermined decoding algorithm and correcting a predetermined number of errors and the declared erasures, and detecting data from a result of correcting the errors and erasures.

Abstract: A weighted secret sharing and reconstructing method includes encoding the secret using a predetermined code, producing voices so that different weights are assigned to errors in an error vector according to locations of the errors, encrypting the encoded secret using the error vector and distributing the encrypted encoded secret to a plurality of participants.

Abstract: An encryption method for encrypting data for multi-level access control in an ad-hoc network including hierarchical security classes includes encoding data into a predetermined code using a first public key of a highest security class, adding a private key of a security class to which a user belongs, to the predetermined code, and generating a ciphertext by adding a second public key, published by the security class to which the user belongs, to the addition result. A corresponding decryption method includes subtracting the private key from the ciphertext, performing a first decoding using a secret key known by a security class, to which a receiver belongs, by the receiver of the ciphertext, and correcting errors included in the second public key and detecting the data by performing a second decoding of the result of the first decoding using a code known by the security class to which the receiver belongs.