# US 11,442,922 B2 · Data management method, data management apparatus, and non-transitory computer readable medium

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- Number: US 11,442,922 B2
- Document ID: US11442922B2
- Status: Granted
- Kind: B2
- Application number: 16/566,893
- Filed: 2019-09-11
- Published: 2020-03-26
- Granted: 2022-09-13
- Earliest claimed: 2019-09-11
- Assignees: FUJIFILM Business Innovation Corp.
- Applicants: FUJIFILM Business Innovation Corp.
- Inventors: Taro Terao
- Web page: https://patentgrep.com/patent/US11442922B2

## CPC

- G06F 16/2365: {Ensuring data consistency and integrity}
- H04L 9/3239: {involving non-keyed hash functions, e.g. modification detection codes [MDCs], MD5, SHA or RIPEMD}
- G06F 8/71: Version control (security arrangements therefor G06F21/57); Configuration management
- G06F 21/64: Protecting data integrity, e.g. using checksums, certificates or signatures
- H04L 9/3236: {using cryptographic hash functions}
- H04L 9/3242: {involving keyed hash functions, e.g. message authentication codes [MACs], CBC-MAC or HMAC}
- H04L 63/126: {the source of the received data}
- H04L 9/50: {using hash chains, e.g. blockchains or hash trees}
- H04L 2209/56: Financial cryptography, e.g. electronic payment or e-cash
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A data management method includes: in a case where A denotes a set of symbols, A* denotes a set of all character strings composed of the symbols in A, L denotes a subset of A, and h(L) denotes a mapping performed on L with h that denotes a cryptographical hash function, regarding h: A*→A, multiple peers each hold an inverse mapping hL−1 of hL: L→h(L) that denotes a partial mapping of h, and in a case where at least one original data item M and an encrypted data item C encrypted from the original data item M are present, the encrypted data item C being held in hL−1, and correspondence between the original data item M and the encrypted data item C is to be validated, calculating a hash value h(M); decrypting the encrypted data item C with a hash value k; and comparing a result of the decrypting with the original data item M.

## Claims

### Claim 1

A data management apparatus comprising:
a memory;
a holding unit including a plurality of peers that hides and stores a plurality of original data items M;
a calculation unit;
a decryption unit; and
a comparison unit,
the calculation unit calculating a hash value k of the original data item M among the plurality of the original data item M hold by the holding unit by performing a mapping on the original data item M with a cryptographical hash function, that is, the hash value k is obtained from h(M),
the decryption unit performing decryption of the encrypted data C with the hash value k and obtaining a decrypted data item,
the comparison unit comparing the decrypted data item with the original data M, if the decrypted data item is the same as the original data item M, it is determined that the original data M corresponds to the encrypted data C, which means the encrypted data C is encrypted from the original data M,
if the decrypted data item is not the same as the original data item M, it is determined that the original data M does not correspond to the encrypted data C,
thereby the correspondence between the encrypted data C and the original data M is validated.

### Claim 2 (depends on 1)

The data management apparatus according to claim 1,
wherein the hash value k of the original data item M is set as a privilege identifier,
wherein a hash value p of the encrypted data item C corresponding to the original data item M is set as a public identifier, the hash value p is obtained by performing a mapping on the encrypted data item C with the cryptographical hash function, that is the hash value p is obtained from h(C), and
wherein the holding unit hides and stores a plurality of the original data item M.

### Claim 3 (depends on 2)

The data management method according to claim 2, further comprising
recording a plurality of pairs (p, k), wherein the hash value p is the privilege identifier and the hash value p is the privilege identifier, and
in a case that a content encryption key is lost, the privilege identifier and the privilege identifier is reproduced, and the correspondence between the encrypted data C and the original data M is validated.

### Claim 4

A non-transitory computer readable medium storing a program causing a computer to execute a process, the process comprising:
calculating a hash value k of an original data item M by performing a mapping on the original data item M with a cryptographical hash function, that is, the hash value k is obtained from h(M);
decrypting an encrypted data item C with the hash value k and obtain a decrypted data item; and
comparing the decrypted data item with the original data item M,
if the decrypted data item is the same as the original data item M, it is determined that the original data M corresponds to the encrypted data C, which means the encrypted data C is encrypted from the original data M,
if the decrypted data item is not the same as the original data item M, it is determined that the original data M does not correspond to the encrypted data C,
thereby the correspondence between the encrypted data C and the original data M is validated.

### Claim 5 (depends on 4)

The non-transitory computer readable medium storing the program causing the computer to execute the process according to claim 4, in the process,
wherein the hash value k of the original data item M is set as a privilege identifier,
wherein a hash value p of the encrypted data item C corresponding to the original data item M is set as a public identifier, the hash value p is obtained by performing a mapping on the encrypted data item C with the cryptographical hash function, that is the hash value p is obtained from h(C), and
wherein the holding unit hides and stores a plurality of the original data item M.

### Claim 6 (depends on 5)

The non-transitory computer readable medium storing the program causing the computer to execute the process according to claim 5, the process further comprising
recording a plurality of pairs (p, k), wherein the hash value p is the privilege identifier and the hash value p is the privilege identifier, and
in a case that a content encryption key is lost, the privilege identifier and the privilege identifier is reproduced, and the correspondence between the encrypted data C and the original data M is validated.

### Claim 7

A data management method, adaptive for a cipher system conforming to a distributed electronic ledger technology, wherein the method comprising:
calculating a hash value k of an original data item M by performing a mapping on the original data item M with a cryptographical hash function, that is, the hash value k is obtained from h(M);
decrypting an encrypted data item C with the hash value k and obtain a decrypted data item; and
comparing the decrypted data item with the original data item M,
if the decrypted data item is the same as the original data item M, it is determined that the original data M corresponds to the encrypted data C, which means the encrypted data C is encrypted from the original data M,
if the decrypted data item is not the same as the original data item M, it is determined that the original data M does not correspond to the encrypted data C,
thereby the correspondence between the encrypted data C and the original data M is validated.

### Claim 8 (depends on 7)

The data management method according to claim 7,
wherein the hash value k of the original data item M is set as a privilege identifier,
wherein a hash value p of the encrypted data item C corresponding to the original data item M is set as a public identifier, the hash value p is obtained by performing a mapping on the encrypted data item C with the cryptographical hash function, that is the hash value p is obtained from h(C), and
wherein a specific administrator peer hides and stores a plurality of the original data item M.

### Claim 9 (depends on 8)

The data management method according to claim 8, further comprising
recording a plurality of pairs (p, k), wherein the hash value p is the privilege identifier and the hash value p is the privilege identifier, and
in a case that a content encryption key is lost, the privilege identifier and the privilege identifier is reproduced, and the correspondence between the encrypted data C and the original data M is validated.