SIGBLOCK

SIGBLOCK is a modular security framework that provides policy-driven control over digital signatures in data workflows. It enables organizations to declare and enforce rules about which signatures are accepted, how they are validated, and what actions are taken when a signature is blocked, invalid, or fails revocation checks.

The architecture includes a Policy Engine, a Signature Verification Service, a Block List where known bad keys or signatures are recorded, a Key Management module, and an Audit Logger. It interoperates with standard PKI infrastructure and can support multiple signature algorithms and certificate chains.

During operation, a document or message is processed by SIGBLOCK: the system extracts the signature, applies policy to determine acceptability, verifies cryptographic validity, checks revocation status, and consults the Block List. Depending on results, the item is accepted, flagged for manual review, or rejected.

Key features include a dedicated Policy Language for expressing rules, multi-algorithm support, revocation and key-compromise handling, scalable verification, tamper-evident audit logs, and pluggable connectors for mail systems, document repositories, and software distribution pipelines.

SIGBLOCK is used in email gateways, document management, software distribution, and regulated data exchanges in finance and healthcare. It improves governance of signatures, mitigates risk from compromised keys, and supports compliance with data integrity requirements.

Development remains active in academic and industry contexts, with prototypes and commercial offerings exploring policy-driven signature governance and supply-chain security.