# US 2013/0159697 A1 · Distributing data to multiple clients from server > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0159697 A1 - Document ID: US20130159697A1 - Status: Published application - Kind: A1 - Application number: 13/713,190 - Filed: 2012-12-13 - Published: 2013-06-20 - Earliest claimed: 2011-12-16 - Assignees: International Business Machines Corporation - Inventors: Kohichi Kamijoh; Hisashi Miyashita; Hiroaki Nakamura - Web page: https://patentgrep.com/patent/US20130159697A1 ## CPC - H04L 9/00: {Cryptographic mechanisms or cryptographic} arrangements for secret or secure communications; Network security protocols - H04L 9/0662: {with particular pseudorandom sequence generator} - H04N 21/2347: involving video stream encryption - H04N 21/25875: {involving end-user authentication (restricting access to computer systems by authenticating users using a predetermined code G06F21/33; arrangements for secret or secure communication including means for verifying the identity or authority of a user of the system H04L9/32; networks authentication protocols H04L63/08; authentication in wireless network security H04W12/06)} - H04N 21/4405: involving video stream decryption - H04N 21/4753: {for user identification, e.g. by entering a PIN or password (cryptographic authentication protocols H04L9/32; networks authentication protocols H04L63/08)} - H04N 21/654: Transmission by server directed to the client - H04N 21/8193: {dedicated tools, e.g. video decoder software or IPMP tool} - H04L 2209/08: Randomization, e.g. dummy operations or using noise - H04N 21/26613: {for generating or managing keys in general (key distribution for secret or secure communication involving central third party, e.g. key distribution center [KDC] or trusted third party [TTP] H04L9/083; network support of key management H04L63/06; key management for network security in communication control or processing H04W12/04)} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract Provided are techniques for distributing data in a trackable manner while suppressing an increase in the size of data to be distributed as much as possible and minimizing interruption of usage of the data. A method for distributing data to multiple clients from a server includes the steps of: generating a common noise by using noises unique to the multiple clients, respectively; embedding the common noise in the data to be distributed to make the data unusable; and distributing the data containing the embedded common noise, so that the data containing the embedded common noise is made usable by each of the multiple clients using a unique noise generated in the client. ## Claims ### Claim 1 A method for distributing data to a plurality of clients from a server, the method comprising the steps of: generating a common noise by using noises unique to the plurality of clients, respectively; embedding the common noise in the data to be distributed to make the data unusable; and distributing the data containing the embedded common noise, so that the data containing the embedded common noise is made usable by each of the plurality of clients using a unique noise generated in the client. ### Claim 2 (depends on 1) The method according to claim 1, wherein the unique noise is a synthesis of a first noise and a second noise, the first noise having a larger amplitude than the second noise. ### Claim 3 (depends on 1) The method according to claim 1, wherein the unique noise is generated according to a given parameter. ### Claim 4 (depends on 3) The method according to claim 3, wherein the unique noise N(k,t) of a client k which is one of the plurality of clients is obtained according to the following formula: N(k,t)=αrand(t+s0)+βrand(t+s1k) where N(k,t) is the unique noise of client k, rand( ) is random number generation function having very long cycle (T), t is a variable, α and β are coefficients such that α>1 and 0<β<<1, and s0 and s1k are seeds for client k. ### Claim 5 (depends on 3) The method according to claim 3, wherein when the parameter is t0, the parameter t0 is obtained according to the following formula: t 0 = arg    max t   A  ( t , Δ ) where A  ( t , Δ   t ) = min p , q ∈ D , p ≠ q  ∫ t t + Δ  ( N  ( p , t ) - N  ( q , t ) )    t where A is a minimum difference, t is a variable, Δt is the length in number of cycles) of noise necessary for embedding in content to be distributed, D is a set of clients included in distribution list, p,q is any combination of members in D, and N(q,t) is the unique noise of client k. ### Claim 6 (depends on 3) The method according to claim 3, wherein the distributing step includes a step of sending the parameter, and the data containing the embedded common noise is made usable by each of the clients using the unique noise generated according to the parameter received by the client. ### Claim 7 (depends on 6) The method according to claim 6, wherein distribution data including the parameter and the data containing the embedded common noise is sent to each of the plurality of distribution-target clients, the distribution data encrypted by using an encryption key unique to the client, and wherein each of the clients is provided with the parameter by decrypting the distribution data using a decryption key unique to the client. ### Claim 8 (depends on 1) The method according to claim 1, wherein the generating step includes a step of calculating the mean of the unique noises of the plurality of clients, respectively. ### Claim 9 (depends on 1) The method according to claim 1, wherein the server includes a mechanism for generating the unique noises of all the plurality of clients, and each of the plurality of clients includes a mechanism for generating its own unique noise. ### Claim 10 (depends on 1) The method according to claim 1, wherein the data includes a variable-length code (VLC) portion, and the embedding step includes a step of changing the VLC portion included in the data based on the common noise. ### Claim 11 (depends on 10) The method according to claim 10, wherein the changing step includes the steps of: determining a map generated based on the common noise for a set of VLCs having an equal length; and replacing a VLC in the data according to the map. ### Claim 12 (depends on 11) The method according to claim 11, further comprising the steps of: labeling members included in the set of equal-length codes; and replacing a given VLC portion with a VLC corresponding to a label after replacement calculated according to the following formula: L′=(L−Np(t))modc where L′ is the label corresponding to VLC after replacement, L is the label corresponding to VLC before replacement, Np(t) is common noise, and c is a number of members in set of VLCs having certain length. ### Claim 13 (depends on 10) The method according to claim 10, wherein the common noise is embedded in at least any of a DCT coefficient, a DC component, a macroblock pattern and a motion vector of the data. ### Claim 14 (depends on 10) The method according to claim 10, wherein the changing step includes a step of changing a level of the VLC portion based on the common noise. ### Claim 15 (depends on 14) The method according to claim 14, wherein the step of changing the level of the VLC portion includes a step of embedding information indicating in which direction, positive or negative, the level is changed. ### Claim 16 (depends on 1) The method according to claim 1, wherein in the step of embedding the common noise, a common noise amplified or damped based on a predetermined coefficient is embedded in the data. ### Claim 17 (depends on 16) The method according to claim 16, wherein when the unique noise of a client k which is one of the plurality of clients is N(k,t), the predetermined coefficient is determined by a function dependent on a variable t. ### Claim 18 (depends on 1) The method according to claim 1, wherein the data to be distributed is data of a still image or video. ### Claim 19 (depends on 1) The method according to claim 1, further comprising a step of receiving a distribution list D specifying a plurality of clients to which the data is to be distributed. ### Claim 20 (depends on 1) A computer-readable storage medium comprising executable program code for implementing the method of claim 1. ### Claim 21 A program for distributing data to a plurality of clients from a server, the program causing a computer to execute the steps of: generating a common noise by using noises unique to the plurality of clients, respectively; embedding the common noise in the data to be distributed to make the data unusable; and distributing the data containing the embedded common noise, so that the data containing the embedded common noise is made usable by each of the plurality of clients using a unique noise generated in the client. ### Claim 22 A system for distributing data to a plurality of clients from a server, the system comprising: a unit configured to generate a common noise by using noises unique to the plurality of clients, respectively; a unit configured to embed the common noise in the data to be distributed to make the data unusable; and a unit configured to distribute the data containing the embedded common noise, so that the data containing the embedded common noise is made usable by each of the plurality of clients using a unique noise generated in the client.