WingArc1st and Cybertrust Launch "Trustee eSeal" as Second Digital Trust Service to Address AI Tampering Risks

WingArc1st Inc. (Headquarters: Minato-ku, Tokyo; President and CEO: Jun Tanaka; hereinafter "WingArc1st") and Cybertrust Inc. (Headquarters: Minato-ku, Tokyo; President: Yuji Kitamura; hereinafter "Cybertrust") have jointly developed "Trustee eSeal," a digital trust service that proves the issuer of PDF documents, and will begin offering it on June 30, 2026 (Tue).

With the widespread adoption of generative AI, the risk of tampering with electronic documents is increasing, with malicious instructions or false information that cannot be visually detected being embedded. For corporate transactions, ensuring authenticity is a crucial element.

Against this backdrop, WingArc1st, in collaboration with Cybertrust, has newly developed "Trustee eSeal" to prove the issuer of PDF documents, in addition to "Trustee Timestamp"*1, which proves the existence time of PDF documents. "Trustee eSeal" adopts "iTrust eSeal Certificate"*2 provided by Cybertrust and extends the functionality to apply eSeals to "Trustee," a business form platform.

By applying "Trustee eSeal" to a PDF, it is possible to prove "which organization issued it and when." Recipients can verify the issuing company and its corporate number, thus 100% proving the issuer and ensuring the reliability of the electronic document.

Furthermore, "Trustee Timestamp" will be provided free of charge to users who contract "Trustee eSeal."

By combining proof of "who issued it (Trustee eSeal)" and "when it existed (Trustee Timestamp)," the authenticity of electronic documents can be strongly guaranteed.

This service is the result of a collaboration agreed upon in March 2026 to build a digital trust infrastructure for the AI era, promoting the coexistence of legal reliability and operational efficiency in complete paperless inter-company transactions, and realizing a society that utilizes advanced data in line with the AI era.*3

PDFs, eSeals, and timestamps that comply with international standards maintain future compatibility and vendor-free flexibility. The Certification Authority that issues the "iTrust eSeal Certificate" has passed WebTrust for CA, an international audit standard, and has also undergone strict examination based on JIPDEC's rigorous standards, obtaining "JIPDEC Trusted Service Registration (Certification Authority)" operated under strict regulations. "Trustee eSeal" ensures the highest level of reliability by adopting the "iTrust eSeal Certificate," which is issued based on these strict operational standards.

"Trustee" Services Addressing AI Tampering Risks

Item

Trustee eSeal

Trustee Timestamp

Proof Function

◎Issuer (Proof of Corporation)

◎Proof of Existence Time

Tampering Detection

◎

◎

Proof of Compliance with Electronic Book Preservation Act

―

◎ (Ensuring Authenticity)

Issuing Company

Electronic Certification Authority

Time Certification Authority

"Trustee eSeal" Feature Highlights

Feature

Details

1

Protection of Electronic Data Content

The content of the data designated for signing by the user is not transmitted to this service; only the hash value is transmitted, so this service does not handle the content of the electronic data.

2

Advanced Security Management of Keys

User's signing keys are securely generated and managed in cryptographic modules (HSMs) certified to FIPS 140-3 Level 3 or higher, or ISO/IEC 15408 EAL4+ or higher.

3

Strict Authentication Requirements

Before applying a signature, strict authentication of authorized users and systems, as well as authorization for the use of signing keys, is performed to confirm that the request is legitimate. Through login authentication, access control, etc., it is confirmed that authorized personnel within the organization are operating according to proper procedures.

A mechanism is in place to technically ensure that the signing key cannot be used by anyone other than the user.

4

Reliability of Certificates

Electronic certificates issued by trusted certification authorities registered in the Adobe Approved Trust List (AATL) are used. This allows for intuitive and visual confirmation of the issuer and the presence of tampering in Adobe Acrobat.

5

Support for Long-Term Signature Format

By embedding the signature timestamp and verification information, and applying an archive timestamp in addition to the signature value obtained from this service, the signature generation application can create long-term signature format (PAdES-LTV) that allows for long-term verification of signature authenticity even after the electronic certificate expires.

6

Availability and Operational Continuity

This service is provided 24 hours a day, 365 days a year, except for pre-notified service maintenance periods and emergency maintenance.

7

International Standards

Based on the CSC (Cloud Signature Consortium) API* international standard, the mechanism to ensure that only the key owner can use the signing key is strengthened.

* https://cloudsignatureconsortium.org/

* The CSC API cannot be used alone; a dedicated "Trustee Client Tool" is required. This tool is provided free of charge to contracted customers.

*1 "Trustee Timestamp" uses the certified time certification service "WingArc Timestamp Service" related to the Ministry of Internal Affairs and Communications Notification No. 146 of Reiwa 3.

*2 Regarding iTrust eSeal Certificate

The iTrust eSeal Certificate utilizes an "Electronic Certificate for eSeal" issued only to organizations strictly vetted by Cybertrust. By applying an eSeal to electronic documents issued by an organization, it enables proof of issuer and tamper-proofing, ensuring high reliability and authenticity for electronic documents. *3 WingArc1st and Cybertrust Collaborate to Build a Digital Trust Infrastructure for the AI Era

About WingArc1st Inc.

WingArc1st provides business form and document management solutions that support the efficient operation of all business process forms, and data empowerment solutions that promote business reform for growth through data utilization. By providing innovative software and services that support data-driven decision-making and actions, we are creating a future where companies and organizations can maximize their data utilization and drive innovation. The company entered the digital trust service market in 2025 and began offering "Trustee." WingArc1st is selected as a "2026 Certified Health & Productivity Stock" company. Furthermore, on January 31, 2024, it obtained certification for "ISO 30414," an international guideline for human capital disclosure, the first in the information and communications industry.

About Cybertrust Inc.

Cybertrust offers trust services utilizing authentication and security technologies provided since 2000 as Japan's first commercial certification authority, as well as platform services for on-premises, cloud, and embedded domains applying Linux kernel technology and open-source software (OSS) expertise. Furthermore, by combining these technologies and achievements, the company promotes services that prove the correctness of "people, things, and events" for advanced fields such as IoT, supporting the reliability of customer services.

"Trust in all people, things, and events." Cybertrust realizes a safe and secure society with highly specialized and neutral technologies related to IT infrastructure.

URL for this Release https://www.cybertrust.co.jp/pressrelease/2026/0630-wingarc-itrust.html

* Company names, product names, and service names mentioned in this press release are trademarks or registered trademarks of our company or each company and organization.