Privacy-compliant proxy
system for large language models, comprehensive: a) an
authentication module for validating user access using API keys, JWT tokens or cookies with role-based
access control, b) a multi-layered PIl recognition module with at least four parallel recognition
layers, comprising a neural
named entity recognition layer, a rule-based regex recognition layer, a keyword-based recognition layer, and a context-based recognition layer, c) a
pseudonymization module for replacing identified personal data with type-preserving pseudonyms with session-consistent assignment and randomized starting counters as an anti-cardinality measure, d) a multi-provider proxy module for forwarding pseudonymized requests to at least one external AI
language model provider, e) a de-
pseudonymization module for retranslating the pseudonyms in the AI response and a response PII redaction module for detecting and redacting AI-generated new personal data in the response, characterized in that f) a
hybrid signature and audit chain module is provided which generates an audit entry for each transaction, signs it with both a classical signature method (Ed25519) and a post-
quantum secure signature method (ML-DSA-65), and links the entries in a
hash chain, with each signature being verified immediately after generation and before being written to the
database (write-time
verification), and g) a zero-knowledge
encryption module is provided which encrypts the audit entries after signing with a user-specific Data
Encryption Key (DEK), the DEK being derived from the user
password and existing only in
volatile memory during the active session, and the
hash chain and signatures being preserved in
plaintext so that the integrity of the audit chain can be verified without decrypting the contents.