WingArc and Cybertrust Launch "Trustee eSeal" Digital Trust Service to Address AI Tampering Risks

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

Against the backdrop of 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 confirmed being embedded. For corporate business transactions, ensuring authenticity is a crucial element.

In response to this situation, WingArc, in collaboration with Cybertrust, has newly developed "Trustee eSeal" to prove the issuer of PDF documents, in addition to "Trustee Timestamp" (Note 1), which proves the existence time of PDF documents. "Trustee eSeal" adopts Cybertrust's "iTrust eSeal Certificate" (Note 2) and expands the functionality to apply eSeals to "Trustee," a ledger platform.

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

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 both legal reliability and operational efficiency in the complete paperless transition of inter-company transactions, and realizing a highly data-driven society suited for the AI era. (Note 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 obtained "JIPDEC Trusted Service Registration (Certification Authority)" which is operated under strict regulations based on rigorous screening by JIPDEC. "Trustee eSeal" ensures the highest level of reliability by adopting the "iTrust eSeal Certificate" issued under these strict operational standards.

"Trustee" Services to Address 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 URL: https://www.wingarc.com/product/trustee/

Feature

Details

1

Protection of Electronic Data Content

The content of the data designated for signature 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

The 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 from the user. Through login authentication and access control, 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 during pre-notified service maintenance periods and emergency maintenance.

7

International Standards

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

* https://cloudsignatureconsortium.org/ * The API alone cannot be used; a dedicated "Trustee Client Tool" is required. This will be provided free of charge to contract customers.

(Note 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.

https://www.soumu.go.jp/menu_news/s-news/01cyber01_02000001_00245.html

(Note 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 is possible to prove the issuer and prevent tampering, ensuring high reliability and authenticity for electronic documents. https://www.cybertrust.co.jp/e-seal-certificate/

(Note 3) WingArc1st and Cybertrust Collaborate to Build a Digital Trust Infrastructure for the AI Era https://corp.wingarc.com/public/202603/news2957.html

About WingArc1st Inc.

WingArc1st provides ledger and document management solutions that support the efficient operation of all business processes, 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 fully utilize data and drive innovation. In 2025, we entered the digital trust service market and began offering "Trustee." Our company is selected as a "Health Management Brand 2026" company. Furthermore, on January 31, 2024, we obtained certification for "ISO 30414," an international guideline for human capital information 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 electronic certification authority, and 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, we promote services that prove the correctness of "people, things, and events" for advanced fields including IoT, supporting the reliability of our customers' services. "Trust for all people, things, and events." Cybertrust realizes a safe and secure society with highly specialized and neutral technology related to IT infrastructure.

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