Abstract: An operation method for an instant messenger server is provided. The method includes generating a schedule which depends on an account of a host in response to a schedule generation request of the host, determining invitees based on at least one of a chat room list and a friend list of the account of the host, synchronizing schedules which depend on accounts of users who participate in the schedule, based on whether at least one guest included in the invitees participates, and providing a notification of the schedule to at least one of the users who participate in the schedule, through a user interface (UI) of a chat room provided through the instant messaging service.

Abstract: An operation method for an instant messenger server is provided. The method includes generating a schedule which depends on an account of a host in response to a schedule generation request of the host, determining invitees based on at least one of a chat room list and a friend list of the account of the host, synchronizing schedules which depend on accounts of users who participate in the schedule, based on whether at least one guest included in the invitees participates, and providing a notification of the schedule to at least one of the users who participate in the schedule, through a user interface (UI) of a chat room provided through the instant messaging service.

Abstract: A surveillance server connected to a camera through a network is provided, the camera acquiring an image of a surveillance area. The surveillance server includes: a data acquisition unit configured to acquire from the camera image data of the image that is encrypted; a mode selection unit configured to select a processing mode of the image data; and a decryption control unit configured to decrypt the image data in response to selection of a first mode.

Abstract: A surveillance server connected to a camera through a network is provided, the camera acquiring an image of a surveillance area. The surveillance server includes: a data acquisition unit configured to acquire from the camera image data of the image that is encrypted; a mode selection unit configured to select a processing mode of the image data; and a decryption control unit configured to decrypt the image data in response to selection of a first mode.

Abstract: An encryption method and apparatus thereof is disclosed. In one embodiment the method includes (a) receiving the content data via the network, (b) changing a sequence of the received content data according to a predetermined algorithm or randomly to store in a form of a cache file, (c) generating a decryption key including information of the changed sequence of the data, and (d) encrypting the decryption key according to a predetermined encryption system, wherein if a playback or transmission of the stored content is requested, the encrypted decryption key is decrypted and the corresponding data is extracted from the cache file according to the sequence information of the decryption key to be played back or transmitted. According to one embodiment of the invention, a user is unable to illegally use content data stored in his local client and content data stored in a local client can be quickly decrypted so as not to affect playback of the content data.

Abstract: Disclose is a method and system enabling joint viewing of moving picture while chatting. In order to match the screen being played and chatting message, a method for synchronizing contents playing times for the contents being played is further disclosed. A room master client among user clients joined the joint viewing room receives buffering state information from all clients in joint viewing and transmits playback start message to the clients in joint viewing according to the buffering state information. After contents playback is started, the room master client provides information on current contents playing time to the other user clients periodically, and the other clients synchronize contents playing times based on the current contents playing time of the room master client.

Abstract: Disclose is a method and system enabling joint viewing of moving picture while chatting. In order to match the screen being played and chatting message, a method for synchronizing contents playing times for the contents being played is further disclosed. A room master client among user clients joined the joint viewing room receives buffering state information from all clients in joint viewing and transmits playback start message to the clients in joint viewing according to the buffering state information. After contents playback is started, the room master client provides information on current contents playing time to the other user clients periodically, and the other clients synchronize contents playing times based on the current contents playing time of the room master client.

Abstract: An encryption method and apparatus thereof is disclosed. In one embodiment the method includes (a) receiving the content data via the network, (b) changing a sequence of the received content data according to a predetermined algorithm or randomly to store in a form of a cache file, (c) generating a decryption key including information of the changed sequence of the data, and (d) encrypting the decryption key according to a predetermined encryption system, wherein if a playback or transmission of the stored content is requested, the encrypted decryption key is decrypted and the corresponding data is extracted from the cache file according to the sequence information of the decryption key to be played back or transmitted. According to one embodiment of the invention, a user is unable to illegally use content data stored in his local client and content data stored in a local client can be quickly decrypted so as not to affect playback of the content data.