tftsr-devops_investigation/docs/wiki/Security-Model.md

Security Model

Threat Model Summary

TFTSR handles sensitive IT incident data including log files that may contain credentials, PII, and internal infrastructure details. The security model addresses:

1. Data at rest — Database encryption
2. Data in transit — PII redaction before AI send, TLS for all outbound requests
3. Secret storage — API keys in Stronghold vault
4. Audit trail — Complete log of every external data transmission
5. Least privilege — Minimal Tauri capabilities

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Database Encryption (SQLCipher AES-256)

Production builds use SQLCipher:

• Cipher: AES-256-CBC
• KDF: PBKDF2-HMAC-SHA512, 256,000 iterations
• HMAC: HMAC-SHA512
• Page size: 16384 bytes
• Key source: TFTSR_DB_KEY environment variable

Debug builds use plain SQLite (no encryption) for developer convenience.

Release builds now fail startup if TFTSR_DB_KEY is missing or empty.

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Credential Encryption

Integration tokens are encrypted with AES-256-GCM before persistence:

• Key source: TFTSR_ENCRYPTION_KEY (required in release builds)
• Key derivation: SHA-256 hash of key material to a fixed 32-byte AES key
• Nonce: Cryptographically secure random nonce per encryption

Release builds fail secure operations if TFTSR_ENCRYPTION_KEY is unset or empty.

The Stronghold plugin remains enabled and now uses a per-installation salt derived from the app data directory path hash instead of a fixed static salt.

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PII Redaction

Mandatory path: No text can be sent to an AI provider without going through the PII detection and user-approval flow.

log file → detect_pii() → user approves spans → apply_redactions() → AI provider

• Original text never leaves the machine
• Only the redacted version is transmitted
• The SHA-256 hash of the redacted text is recorded in the audit log for integrity verification
• pii_spans.original_value is cleared after redaction to avoid retaining raw detected secrets in storage
• See PII Detection for the full list of detected patterns

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Audit Log

Every external data transmission is recorded:

write_audit_event(
    &conn,
    action,       // "ai_send", "publish_to_confluence", etc.
    entity_type,  // "issue", "document"
    entity_id,    // UUID of the related record
    details,      // JSON: provider, model, hashes, log_file_ids
)?;

The audit log is stored in the encrypted SQLite database. It cannot be deleted through the UI.

Tamper Evidence

audit_log entries now include:

• prev_hash — hash of the previous audit entry
• entry_hash — SHA-256 hash of current entry payload + prev_hash

This creates a hash chain and makes post-hoc modification detectable.

Audit entry fields:

• action — what was done
• entity_type — type of record involved
• entity_id — UUID of that record
• user_id — always "local" (single-user app)
• details — JSON blob with hashes and metadata
• timestamp — UTC datetime

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Tauri Capabilities (Least Privilege)

Defined in src-tauri/capabilities/default.json:

Plugin	Permissions granted
dialog	allow-open, allow-save
fs	read-text, write-text, read, write, mkdir — scoped to app dir and temp
shell	allow-open only
http	default — connect only to approved origins

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Content Security Policy

default-src 'self';
style-src 'self' 'unsafe-inline';
img-src 'self' data: asset: https:;
connect-src 'self'
  http://localhost:11434
  https://api.openai.com
  https://api.anthropic.com
  https://api.mistral.ai
  https://generativelanguage.googleapis.com;

HTTP is blocked by default. Only whitelisted HTTPS endpoints (and localhost for Ollama) are reachable.

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TLS

All outbound HTTP requests use reqwest with certificate verification enabled and a request timeout configured for provider calls.

CI/CD currently uses internal http:// endpoints for self-hosted Gitea release automation on a trusted LAN. Recommended hardening: migrate runners and API calls to HTTPS with internal certificates.

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Security Checklist for New Features

• Does it send data externally? → Add audit log entry
• Does it handle user-provided text? → Run PII detection first
• Does it store secrets? → Use Stronghold, not the SQLite DB
• Does it need filesystem access? → Scope the fs capability
• Does it need a new HTTP endpoint? → Add to CSP connect-src
• Does it add a new provider endpoint? → Avoid query-param secrets, use auth headers