HSM-Backed Sign Server Architecture

Digital signatures are only as strong as the protection of the private key. If the key is exposed, copied, or mishandled, the legal and technical value of every signature collapses.

Khatim Sign Server’s hsm-backed sign server architecure is designed so that cryptographic keys remain protected inside certified hardware or trusted cloud vaults, while applications still get the speed and automation they require.

Why Keys Must Stay in Hardware

Private keys represent authority. Moving them into files, application memory, or desktops dramatically increases the attack surface.

By performing signing operations inside Hardware Security Modules (HSMs) or managed cloud key vaults, organizations gain:

• Strong isolation from operating systems

• Protection against extraction and tampering

• Role-based access control

• Cryptographic operations within certified boundaries

• Reliable audit evidence

This approach ensures signatures remain defensible even under regulatory scrutiny or legal challenge.

Compliance Drivers

Regulated industries, QTSPs, and enterprises operating under eIDAS, financial, or healthcare mandates must demonstrate strict control over signing keys.

Auditors routinely expect:

• Hardware-backed key storage

• Controlled access to cryptographic operations

• Traceable usage

• Separation of duties

• Tamper resistance

An HSM-centric design is therefore not optional – it is foundational.

Khatim aligns operational efficiency with these expectations, enabling compliant service delivery without slowing the business.

Remote Signing Model

In a modern enterprise, documents originate from many systems – ERP, CRM, billing engines, contract platforms, citizen portals. Instead of spreading keys across environments, Khatim Sign Server centralizes them. Applications simply send signing requests via secure RESTful APIs. The server authenticates the request, applies policy, invokes the HSM or cloud KMS, and returns a compliant signature. Business systems never touch the private key.
They simply receive trusted results.

Khatim Integrations with HSM & Cloud KMS

Khatim Sign Server is designed to integrate seamlessly with both on-premise Hardware Security Modules and cloud-based key management platforms. For traditional HSM deployments, administrators can either

• Generate new cryptographic keys directly inside the device or securely import existing keys according to organizational policy.

• For globally trusted workflows such as AATL signatures, Khatim also supports the use of asymmetric keys already protected within cloud KMS providers like AWS or Azure. These keys remain under hardware-backed protection in the cloud while Khatim handles policy enforcement, certificate lifecycle, and signing orchestration.

AATL-Based Signatures with AWS/Azure

The platform supports Adobe Approved Trust List (AATL) based PDF signatures backed by AWS Key Management Service (KMS) or Azure Key Vaults. This means every signature is not only secure but also globally recognized by Adobe and other relying parties.

Organizations can leverage cloud-hosted hardware protection while maintaining enterprise governance.

Configuring AATL-based keys is straightforward:

• Configure AWS/Azure KMS/KeyVault in System Keys → Key Vault

• Import asymmetric keys using

  • ARN, Client ID, and Client Secret

  • Application / Client ID, Directory / Tenant ID and Secret Value

• Generate a CSR from the imported key

• Have the CSR certified by a trusted AATL Certification Authority

• Import the issued X.509 certificate back into the system

• Create a signing policy and bind the certificate

• Send PDFs via REST APIs and sign using required PAdES profiles

The result: hardware-backed, globally trusted signatures delivered through modern automation.