# US 12,120,244 B2 · Human readable content for digital signatures

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- Number: US 12,120,244 B2
- Document ID: US12120244B2
- Status: Granted
- Kind: B2
- Application number: 17/702,135
- Filed: 2022-03-23
- Published: 2023-09-28
- Granted: 2024-10-15
- Earliest claimed: 2022-03-23
- Assignees: The United States of America as represented by the Secretary of the Navy
- Applicants: United States of America as represented by the Secretary of the Navy
- Inventors: Matthew Galligan; John P. Waxler; Nhan Nguyen
- Web page: https://patentgrep.com/patent/US12120244B2

## CPC

- H04L 9/0631: {Substitution permutation network [SPN], i.e. cipher composed of a number of stages or rounds each involving linear and nonlinear transformations, e.g. AES algorithms}
- H04L 9/3247: {involving digital signatures}
- H04L 9/006: {involving public key infrastructure [PKI] trust models (network architecture or network communication protocol for supporting authentication of entities using certificates in a packet data network H04L63/0823)}
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A method for increasing validity of digital signatures comprising: receiving a request from a browser to have a user apply a digital signature to a document; verifying that the document complies with a predefined ruleset (e.g., prescribing font colors); presenting the user with the document on a user-computer interface in such a way that the document's entire content is completely reviewable by the user only if the document complies with the predefined ruleset; upon receiving instruction from the user to sign the document, generating a digital signature according to Advanced Encryption Standard (AES) public key infrastructure (PKI) that protects the document in its entirety, as presented to the user in the previous step; enabling the user to perform one or more of printing, sharing, and saving the digitally-signed document in a memory store; and sending the digitally-signed document with the newly-generated signature to the browser.

## Claims

### Claim 1

A method for increasing validity of digital signatures comprising the following steps:
receiving with an operating system running on a computer operated by a user, a request from a browser to have the user apply a digital signature to a document, wherein the document originates from a website;
verifying with the operating system that the document complies with a predefined ruleset before the user is given an opportunity to apply the digital signature, wherein the predefined ruleset prescribes font colors;
if the document does not comply with the predefined ruleset, declining to present the document to the user for the digital signature;
if the document does comply with the predefined ruleset, presenting the user with the document on a user-computer interface in such a way that the document's entire content is completely visible and reviewable by the user;
upon receiving instruction from the user to sign the document, generating the digital signature according to public key infrastructure (PKI) to create a digitally-signed document that replicates the document in its entirety as presented to the user in the presenting step without any additions or deletions to the document but for the addition of the digital signature;
enabling the user to perform one or more of printing, sharing, and saving the digitally-signed document in a memory store; and
sending the digitally-signed document to the browser.

### Claim 2 (depends on 1)

The method of claim 1, wherein the steps are performed in the browser only without requiring any native digital-signature-related software to be installed on the user's computer.

### Claim 3 (depends on 1)

The method of claim 1, wherein the predefined ruleset requires that the document include only raw text.

### Claim 4 (depends on 1)

The method of claim 1, wherein the predefined ruleset requires that the document include only raw text and bitmap format images.

### Claim 5 (depends on 1)

The method of claim 1, wherein the predefined ruleset includes portable document format (PDF) only once an internal validation is performed to ensure that text formatting is within acceptable ranges, and there are no ‘hidden’ payloads.

### Claim 6 (depends on 1)

The method of claim 1, wherein the step of generating the digital signature comprises using binary/string concatenation to protect the entirety of the document.

### Claim 7 (depends on 1)

The method of claim 1, wherein the step of generating the digital signature comprises hashing the entire document such that the digital signature protects the entirety of the document.

### Claim 8 (depends on 1)

The method of claim 1, wherein the step of generating the digital signature comprises using attributes of an e-pen signature to create a key that ties the digital signature to the digitally-signed document as evidence that the e-pen signature was used to sign the digitally-signed document, but not another.

### Claim 9

A method for increasing validity of a digital signature comprising the following steps:
loading a configuration file on an operating system running on a computer, wherein the configuration file is configured to force public key infrastructure (PKI) on documents that require the digital signature from a user of the computer;
receiving with the operating system, a request to have the user apply the digital signature to a given document;
verifying, with the operating system, that the given document complies with a predefined ruleset before the user is given an opportunity to apply the digital signature to the given document, wherein the predefined ruleset prescribes font size, color, and legibility standards, and wherein the predefined ruleset prohibits inclusion of data in the given document that is not explicitly defined and allowed by the predefined ruleset;
presenting the user with the given document on a user-computer interface in such a way that an entire content of the given document is completely reviewable by the user only if the given document complies with the predefined ruleset;
upon the operating system receiving instruction from the user to sign the given document, generating the digital signature according to public key infrastructure (PKI) thereby creating a digitally-signed document that replicates the entire content of the given document, as presented to the user in the presenting step;
enabling the user to perform one or more of printing, sharing, and saving the digitally-signed document in a memory store; and
sending the digitally-signed document to a browser.

### Claim 10 (depends on 9)

The method of claim 9, wherein the request to have the user apply the digital signature to a given document comes from a website.

### Claim 11 (depends on 10)

The method of claim 10, wherein the digitally-signed document is protected such that once the digital signature is generated no content changes may be made to the digitally-signed document.

### Claim 12 (depends on 11)

The method of claim 11, wherein the digitally-signed document is further protected such that any future distribution of the digitally-signed document is subject to distribution limitations.

### Claim 13 (depends on 12)

The method of claim 12, wherein the distribution limitations include an expiration date after which the digitally-signed document will no longer be readable.

### Claim 14 (depends on 12)

The method of claim 12, wherein the distribution limitations include limiting the distribution of the digitally-signed document to a predefined list of recipients.

### Claim 15 (depends on 9)

The method of claim 9, wherein the predefined ruleset is implemented in a language selected from a group consisting of Extensible Markup Language (XML), JavaScript Object Notation (JSON), and Yet Another Markup Language (YAML).