# US 11,121,854 B2 · Imaging module, image processing device, and image processing method

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- Number: US 11,121,854 B2
- Document ID: US11121854B2
- Status: Granted
- Kind: B2
- Application number: 16/229,278
- Filed: 2018-12-21
- Published: 2019-06-27
- Granted: 2021-09-14
- Earliest claimed: 2017-12-22
- Assignees: Axell Corporation
- Applicants: Axell Corporation
- Inventors: Kazuki Kyakuno; Yusuke Hoshizuki
- Web page: https://patentgrep.com/patent/US11121854B2

## CPC

- H04L 9/008: {involving homomorphic encryption}
- G06N 3/04: Architecture, e.g. interconnection topology
- G06N 3/0464: Convolutional networks [CNN, ConvNet]
- G06N 3/09: Supervised learning
- H04L 9/14: using a plurality of keys or algorithms
- H04L 9/3093: {involving Lattices or polynomial equations, e.g. NTRU scheme}
- H04L 9/3297: {involving time stamps, e.g. generation of time stamps}
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- G06N: COMPUTING ARRANGEMENTS BASED ON SPECIFIC COMPUTATIONAL MODELS

## Abstract

An aspect of the invention is directed to an imaging module including: an imaging device which converts an input optical image into image data; an encryption device which encrypts the image data by a homomorphic encryption method; and an interface which outputs encrypted image data received from the encryption device.

## Claims

### Claim 1

A non-transitory computer readable recording medium storing an image processing program which causes a processor of an imaging module to execute:
converting an input optical image into image data;
encrypting the image data by a homomorphic encryption method;
outputting the encrypted image data;
receiving a result signal that is encrypted by the homomorphic encryption method and is a result of processing performed on the encrypted image data;
decrypting the result signal; and
outputting the decrypted result signal,
wherein a data amount of the result signal that can be decrypted by the decrypting in a prescribed time is smaller than a data amount of the image data that can be encrypted by the encrypting in the prescribed time.

### Claim 2 (depends on 1)

The non-transitory computer readable recording medium storing the image processing program according to claim 1, wherein the outputting of the encrypted image data further comprises outputting a public key.

### Claim 3 (depends on 1)

The non-transitory computer readable recording medium storing the image processing program according to claim 1, wherein the image processing program further causes the processor of the imaging module to execute:
generating a public key with which a constant to be used in an inference process is to be encrypted, wherein
the outputting of the encrypted image data further comprises outputting the encrypted image data and the public key to an inference device which encrypts, with the public key, the constant to be used in the inference process and performs, with the encrypted image data that is not decrypted, the inference process, and
the receiving comprises receiving the encrypted result signal that is inferred in the inference device with the encrypted image data.

### Claim 4

A non-transitory computer readable recording medium storing an image processing program which causes a processor of an imaging module to execute:
converting an input optical image into image data;
encrypting the image data by a homomorphic encryption method;
adding a time stamp to the encrypted image data and outputting the encrypted image data;
receiving an input signal;
referring to a time stamp added to the input signal;
when a time longer than or equal to a prescribed threshold time has not elapsed from a time indicated by the time stamp, decrypting the input signal, which is a result signal that is encrypted by the homomorphic encryption method and is a result of processing performed on the encrypted image data and outputting the decrypted result signal; and
when a time longer than or equal to the prescribed threshold time has elapsed from the time indicated by the time stamp, abstaining from decrypting the input signal.

### Claim 5 (depends on 4)

The non-transitory computer readable recording medium storing an image processing program according to claim 4, wherein the outputting of the encrypted image data further comprises outputting a public key.

### Claim 6 (depends on 4)

The non-transitory computer readable recording medium storing the image processing program according to claim 4, wherein the image processing program further causes the processor of the imaging module to execute:
generating a public key with which a constant to be used in an inference process is to be encrypted, wherein
the outputting of the encrypted image data further comprises outputting the encrypted image data and the public key to an inference device which encrypts, with the public key, the constant to be used in the inference process and performs, with the encrypted image data that is not decrypted, the inference process, and
the receiving comprises receiving the encrypted result signal that is inferred in the inference device with the encrypted image data.

### Claim 7

A non-transitory computer readable recording medium storing an image processing program which causes a processor of an imaging module to execute:
converting an input optical image into image data;
generating a public key and a private key every image frame;
encrypting the image data by a homomorphic encryption method;
outputting the encrypted image data;
receiving a result signal that is encrypted by the homomorphic encryption method and is a result of processing performed on the encrypted image data;
decrypting the result signal; and
outputting the decrypted result signal, wherein
the encrypting comprises encrypting pixel values of each image frame with a public key that is dedicated to the image frame, and
the decrypting comprises decrypting the result signal with the private key such that a number of times decryption can be performed with each private key is restricted to a prescribed upper limit number.

### Claim 8 (depends on 7)

The non-transitory computer readable recording medium storing the image processing program according to claim 7, wherein the outputting of the encrypted image data further comprises outputting a public key.

### Claim 9 (depends on 7)

The non-transitory computer readable recording medium storing the image processing program according to claim 7, wherein the image processing program further causes the processor of the imaging module to execute:
generating a public key with which a constant to be used in an inference process is to be encrypted, wherein
the outputting of the encrypted image data further comprises outputting the encrypted image data and the public key to an inference device which encrypts, with the public key, the constant to be used in the inference process and performs, with the encrypted image data that is not decrypted, the inference process, and
the receiving comprises receiving the encrypted result signal that is inferred in the inference device with the encrypted image data.

### Claim 10

An imaging module comprising:
a control circuit configured to
convert an input optical image into image data,
encrypt the image data by a homomorphic encryption method; and
an interface configured to
output the encrypted image data, and
receive a result signal that is encrypted by the homomorphic encryption method and is a result of processing performed on the encrypted image data,
wherein the control circuit is further configured to decrypt the result signal,
wherein the interface is further configured to output the decrypted result signal, and
wherein a data amount of the result signal that can be decrypted by the control circuit in a prescribed time is smaller than a data amount of the image data that can be encrypted by the control circuit in the prescribed time.

### Claim 11 (depends on 10)

The imaging module according to claim 10, wherein the interface is further configured to output the encrypted image data and a public key.

### Claim 12 (depends on 10)

The imaging module according to claim 10, wherein
the control circuit is further configured to generate a public key with which a constant to be used in an inference process is to be encrypted, and
the interface is further configured to
output the encrypted image data and the public key to an inference device which encrypts, with the public key, the constant to be used in the inference process and performs, with the encrypted image data that is not decrypted, the inference process, and
receive the encrypted result signal that is inferred in the inference device with the encrypted image data.

### Claim 13

An imaging module comprising:
a control circuit configured to
convert an input optical image into image data,
encrypt the image data by a homomorphic encryption method, and
add a time stamp to the encrypted image data; and
an interface configured to
output the encrypted image data, and
receive an input signal, wherein
the control circuit is further configured to refer to a time stamp added to the input signal,
when a time longer than or equal to a prescribed threshold time has not elapsed from a time indicated by the time stamp, the control circuit is further configured to decrypt the input signal, which is a result signal that is encrypted by the homomorphic encryption method and is a result of processing performed on the encrypted image data, and the interface is further configured to output the decrypted result signal, and
when a time longer than or equal to the prescribed threshold time has elapsed from the time indicated by the time stamp, the control circuit is further configured to abstain from decrypting the input signal.

### Claim 14 (depends on 13)

The imaging module according to claim 13, wherein the interface is further configured to output the encrypted image data and a public key.

### Claim 15 (depends on 13)

The imaging module according to claim 13, wherein
the control circuit is further configured to generate a public key with which a constant to be used in an inference process is to be encrypted, and
the interface is further configured to
output the encrypted image data and the public key to an inference device which encrypts, with the public key, the constant to be used in the inference process and performs, with the encrypted image data that is not decrypted, the inference process, and
receive the encrypted result signal that is inferred in the inference device with the encrypted image data.

### Claim 16

An imaging module comprising:
a control circuit configured to
convert an input optical image into image data,
generate a public key and a private key every image frame, and
encrypt the image data by a homomorphic encryption method such that pixel values of each image frame are encrypted with a public key that is dedicated to the image frame; and
an interface configured to
output the encrypted image data, and
receive a result signal that is encrypted by the homomorphic encryption method and is a result of processing performed on the encrypted image data,
wherein the control circuit is further configured to decrypt the result signal with the private key such that a number of times decryption can be performed with each private key is restricted to a prescribed upper limit number, and
wherein the interface is further configured to output the decrypted result signal.

### Claim 17 (depends on 16)

The imaging module according to claim 16, wherein the interface is further configured to output the encrypted image data and a public key.

### Claim 18 (depends on 16)

The imaging module according to claim 16, wherein
the control circuit is further configured to generate a public key with which a constant to be used in an inference process is to be encrypted, and
the interface is further configured to
output the encrypted image data and the public key to an inference device which encrypts, with the public key, the constant to be used in the inference process and performs, with the encrypted image data that is not decrypted, the inference process, and
receive the encrypted result signal that is inferred in the inference device with the encrypted image data.
