# US 10,873,631 B2 · Method for storing data in a cloud and network for carrying out the method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,873,631 B2 - Document ID: US10873631B2 - Status: Granted - Kind: B2 - Application number: 16/579,897 - Filed: 2019-09-24 - Published: 2020-01-16 - Granted: 2020-12-22 - Earliest claimed: 2019-09-24 - Assignees: NEC Corporation - Applicants: NEC Corporation - Inventors: Jens-Matthias Bohli; Ghassan Karame; Frederik Armknecht - Web page: https://patentgrep.com/patent/US10873631B2 ## CPC - H04L 67/1097: for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS] - G06F 3/0619: {in relation to data integrity, e.g. data losses, bit errors} - G06F 3/065: {Replication mechanisms} - G06F 11/2056: {by mirroring} - H04L 9/3271: {using challenge-response} - H04L 63/123: {received data contents, e.g. message integrity} - H04L 67/06: specially adapted for file transfer, e.g. file transfer protocol [FTP] - H04L 67/1095: Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes - H04L 9/008: {involving homomorphic encryption} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract A method for storing data in a cloud includes receiving at least one data file to be stored together with a predefined number t of replicas of the at least one data file within the cloud, at least one authentication tag corresponding to the at least one data file and t functions that are configurable to take at least a predefined time to compute; storing the at least one data file within the cloud; computing t solutions of the t functions within the cloud; generating the t replicas of the at least one data file based on the t solutions of the t functions and the at least one data file within the cloud, wherein each of the t functions is used for at least one of the t replicas of the at least one data file; and storing the t replicas within the cloud. ## Claims ### Claim 1 A method for storing data in a cloud, the method comprising: receiving at least one data file to be stored together with a predefined number t of replicas of the at least one data file within the cloud, at least one authentication tag corresponding to the at least one data file and t functions that are configurable to take at least a predefined time to compute; storing the at least one data file within the cloud; computing t solutions of the t functions within the cloud; generating the t replicas of the at least one data file based on the t solutions of the t functions and the at least one data file within the cloud, wherein each of the t functions is used for at least one of the t replicas of the at least one data file; and storing the t replicas within the cloud. ### Claim 2 (depends on 1) The method according to claim 1, wherein the t functions each are not parallelizable and/or comprise an exponent E and/or comprise a one-way function. ### Claim 3 (depends on 1) The method according to claim 1, wherein the t functions are time-lock puzzles. ### Claim 4 (depends on 3) The method according to claim 3, wherein at least one or each of the time-lock puzzles is based on exponentiation modulo a composite number. ### Claim 5 (depends on 3) The method according to claim 3, wherein at least one or each of the time-lock puzzles exhibits a trapdoor based on an Euler totient function. ### Claim 6 (depends on 3) The method according to claim 3, wherein at least one or each of the time-lock puzzles is based on finding a pre-image of a one-way function. ### Claim 7 (depends on 1) The method according to claim 1, wherein each of the t solutions is efficiently verifiable. ### Claim 8 (depends on 1) The method according to claim 1, wherein the receiving includes receiving a processed file comprising the at least one data file and the at least one authentication tag. ### Claim 9 (depends on 1) The method according to claim 1, further including receiving a challenge issued for blocks contained across all of the t replicas. ### Claim 10 (depends on 9) The method according to claim 9, further including computing a response to the challenge under consideration of the at least one authentication tag and the at least one data file and the t replicas stored. ### Claim 11 A method for storing data to a cloud, the method comprising: providing at least one data file to be stored together with a predefined number t of replicas of the at least one data file within the cloud, at least one authentication tag corresponding to the at least one data file and t functions that are configurable to take at least a predefined time to compute; and transmitting the at least one data file, the at least one authentication tag and the t functions to a cloud storage service, to enable the cloud storage service to: store the at least one data file within the cloud; compute t solutions of the t functions within the cloud; generate the t replicas of the at least one data file based on the t solutions of the t functions and the at least one data file within the cloud, wherein each of the t functions is used for at least one of the t replicas of the at least one data file; and store the t replicas within the cloud. ### Claim 12 (depends on 11) The method according to claim 11, wherein the t functions each are not parallelizable and/or comprise an exponent E and/or comprise a one-way function. ### Claim 13 (depends on 11) The method according to claim 11, wherein the t functions are time-lock puzzles. ### Claim 14 (depends on 13) The method according to claim 13, wherein at least one or each of the time-lock puzzles is based on exponentiation modulo a composite number. ### Claim 15 (depends on 13) The method according to claim 13, wherein at least one or each of the time-lock puzzles exhibits a trapdoor based on an Euler totient function. ### Claim 16 (depends on 13) The method according to claim 13, wherein at least one or each of the time-lock puzzles is based on finding a pre-image of a one-way function. ### Claim 17 (depends on 11) The method according to claim 11, wherein each of the t solutions is efficiently verifiable. ### Claim 18 (depends on 11) The method according to claim 11, wherein the transmitting includes transmitting a processed file comprising the at least one data file and the at least one authentication tag. ### Claim 19 (depends on 11) The method according to claim 11, further including issuing a challenge for blocks contained across all of the t replicas. ### Claim 20 (depends on 19) The method according to claim 19, further including receiving a response to the challenge, computed under consideration of the at least one authentication tag and the at least one data file and the t replicas stored.