# US 2017/0286702 A1 · Secured file sharing system

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- Number: US 2017/0286702 A1
- Document ID: US20170286702A1
- Status: Published application
- Kind: A1
- Application number: 15/469,366
- Filed: 2017-03-24
- Published: 2017-10-05
- Earliest claimed: 2016-03-30
- Assignees: PhazrIO Inc.
- Applicants: PhazrIO Inc.
- Inventors: Chi-Kwan J. Cheung
- Web page: https://patentgrep.com/patent/US20170286702A1

## CPC

- G06F 21/606: {by securing the transmission between two devices or processes}
- G06F 21/42: using separate channels for security data
- G06F 21/6209: {to a single file or object, e.g. in a secure envelope, encrypted and accessed using a key, or with access control rules appended to the object itself}
- H04L 51/08: Annexed information, e.g. attachments
- H04L 63/0853: {using an additional device, e.g. smartcard, SIM or a different communication terminal (cryptographic mechanisms or cryptographic arrangements for entity authentication involving additional secure or trusted devices H04L9/3234)}
- H04L 63/18: {using different networks or channels, e.g. using out of band channels (cryptographic mechanisms or cryptographic arrangements for key distribution involving distinctive intermediate devices or communication paths H04L9/0827; cryptographic mechanisms or cryptographic arrangements for authentication using a plurality of channels H04L9/3215)}
- H04L 63/0428: {wherein the data content is protected, e.g. by encrypting or encapsulating the payload}
- H04W 4/14: Short messaging services, e.g. short message services [SMS] or unstructured supplementary service data [USSD]
- 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)
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

One embodiment provides a file sharing system. During operation, the system identifies a data file to be sent to a second device of a second user and generates a plurality of coded fragments from the data file based on a generator matrix of erasure encoding. An individual coded fragment does not include plaintext data. The system generates a plurality of sub-files, each of which comprises one or more coded fragments, of the data file. The system attaches a first sub-file to an electronic communication destined to the second device, uploads a second sub-file to a cloud provider, and embeds a link, which may expire and is protected based on a verification code, associated with the uploaded second sub-file into the electronic communication. The system sends the electronic communication to the second device and the verification code in a text message to a cell phone of the second user.

## Claims

### Claim 1

A method for facilitating secure file sharing, comprising:
identifying, by a first device of a first user, a data file to be sent to a second device of a second user;
generating a plurality of coded fragments from the data file based on a generator matrix of erasure encoding, wherein an individual coded fragment does not include plaintext data of the data file;
generating a plurality of sub-files of the data file, wherein a respective sub-file comprises one or more coded fragments;
attaching a first sub-file of the plurality of sub-files to an electronic communication destined to the second device;
uploading a second sub-file of the plurality of sub-files to a cloud provider;
embedding a link associated with the uploaded second sub-file into the electronic communication, wherein the link is protected based on a verification code;
sending the electronic communication to the second device; and
sending the verification code in a text message to a cell phone of the second user.

### Claim 2 (depends on 1)

The method of claim 1, wherein the electronic communication is one of: an electronic mail (email) and a chat message.

### Claim 3 (depends on 1)

The method of claim 1, further comprising determining a number of sub-files based on a number of communication techniques used to share the data file.

### Claim 4 (depends on 1)

The method of claim 1, further comprising discarding one or more coded fragments based on a minimum number of coded fragments needed to reconstruct the data file.

### Claim 5 (depends on 1)

The method of claim 1, wherein generating the plurality of coded fragments from the data file includes:
obtaining a plurality of data elements from the data file;
converting a respective data element in the plurality of data elements to a numerical representation;
representing the numerical representations as a data matrix; and
multiplying the data matrix with the generator matrix.

### Claim 6 (depends on 1)

The method of claim 1, further comprising maintaining a mapping between an address of the second user and the cell phone number.

### Claim 7 (depends on 6)

The method of claim 6, further comprising attaching a third sub-file of the plurality of sub-files to a chat message destined to a user account of the second user, wherein the mapping further comprises the user account.

### Claim 8 (depends on 1)

The method of claim 1, further comprising determining a number of coded fragments for a respective sub-file based on a size of a file allowed by a corresponding communication technique.

### Claim 9 (depends on 1)

The method of claim 1, wherein the electronic communication further comprises metadata encrypted by a key, wherein the metadata includes one or more of: a number of sub-files, a number of coded fragments in a respective sub-file, and a communication technique for a respective sub-file.

### Claim 10 (depends on 1)

The method of claim 1, further comprising:
determining whether the data file is selected as an attachment from an application facilitating the electronic communication; and
in response to determining that the data file is selected as an attachment, launching a second application facilitating the secure file sharing as a companion application.

### Claim 11

A method for facilitating secure file sharing, comprising:
obtaining, by a first device of a first user, a first sub-file of a data file from an electronic communication sent from a second device of a second user, wherein the first sub-file represents a portion of the data file;
identifying a link associated with a second sub-file of the data file from the electronic communication, wherein the second sub-file is uploaded to a cloud provider, and wherein the link is protected based on a verification code;
obtaining the verification code from the first user, wherein the verification code is sent to a cell phone number of the first user;
obtaining the second sub-file from the cloud provider by providing the verification code to a portal, wherein the link leads to the portal;
retrieving a plurality of coded fragments of the data file from the first and second sub-files, wherein an individual coded fragment does not include plaintext data of the data file; and
reconstructing the data file from the plurality of coded fragments based on a decoder matrix of erasure encoding, wherein the decoder matrix is determined based on a generator matrix used to generate the plurality of coded fragments.

### Claim 12 (depends on 11)

The method of claim 11, wherein the electronic communication is one of: an electronic mail (email) and a chat message.

### Claim 13 (depends on 11)

The method of claim 11, wherein reconstructing the data file comprises:
determining matrix elements associated with the plurality of coded fragments;
determining the decoder matrix by forming the sub-matrix of the generator matrix based on a transformation of the determined matrix elements; and
multiplying the decoder matrix with a data matrix comprising the plurality of coded fragments.

### Claim 14 (depends on 11)

The method of claim 11, further comprising obtaining a third sub-file of the data file from a chat message destined to a user account of the first user.

### Claim 15 (depends on 11)

The method of claim 11, wherein the electronic communication further comprises metadata encrypted by a key, wherein the metadata includes one or more of: a number of sub-files, a number of coded fragments in a respective sub-file, and a communication technique for a respective sub-file.

### Claim 16 (depends on 11)

The method of claim 11, further comprising:
determining whether the first sub-file is selected for downloading from an application facilitating the electronic communication; and
in response to determining that the first sub-file is selected for downloading, launching a second application facilitating the secure file sharing as a companion application.

### Claim 17 (depends on 11)

The method of claim 11, wherein the portal is one of:
a plug-in of the cloud provider, wherein the plug-in is configured to verify the verification code for the second sub-file; and
a web portal running on a web server, wherein the web portal is configured to forward a download request for the second sub-file to the cloud provider in response to verifying the verification code.

### Claim 18 (depends on 11)

The method of claim 11, wherein the verification code is associated with an expiration time.

### Claim 19

A computer system operating as a first device of a first user, the computer system comprising:
a processor; and
a storage device storing instructions that when executed by the processor cause the processor to perform a method, the method comprising:
identifying, by the computer system, a data file to be sent to a second device of a second user;
generating a plurality of coded fragments from the data file based on a generator matrix of erasure encoding, wherein an individual coded fragment does not include plaintext data of the data file;
generating a plurality of sub-files of the data file, wherein a respective sub-file comprises one or more coded fragments;
attaching a first sub-file of the plurality of sub-files to an electronic communication destined to the second device;
uploading a second sub-file of the plurality of sub-files to a cloud provider;
embedding a link associated with the uploaded second sub-file into the electronic communication, wherein the link is protected based on a verification code;
sending the electronic communication to the second device; and
sending the verification code in a text message to a cell phone of the second user.

### Claim 20 (depends on 19)

The computer system of claim 19, wherein the method further comprises attaching a third sub-file of the plurality of sub-files to a chat message destined to a user account of the second user.