transcription/docs/ver1/ver1-step5-results.md

Ver1 Step 5 Results: Private-Network Safety Baseline

Summary

Step 5 implementation status: complete.

This document records completed private-network safety controls, validation evidence, and residual risks for Ver1 Step 5.

Implemented in this step:

1. Added private-network security assumptions and control matrix (docs/ver1/ver1-step5-security-assumptions.md).
2. Implemented optional single-operator access control for /ui* and /api* via HTTP Basic auth.
3. Added upload-size guardrails (MAX_UPLOAD_BYTES) and config fail-fast validation for operator credential requirements.
4. Hardened unexpected-error user-facing messaging to reduce sensitive detail leakage.
5. Added Step 5 tests for access control, security settings, and upload size boundaries.
6. Executed dependency/security scans (pip-audit, bandit) with no critical/high findings.

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Implemented Changes

1) Security assumptions and threat model

Completed.

• Added docs/ver1/ver1-step5-security-assumptions.md defining:
  • trusted private-network deployment assumptions
  • single-operator usage model
  • explicit out-of-scope classes (enterprise IAM, internet-facing zero-trust, multi-tenant controls)
• Added Step 5 control/ownership matrix and residual-risk notes.

2) Single-operator access control baseline

Completed.

• New module: src/transcription/security.py
  • is_protected_path(...) protects /ui* and /api*
  • enforce_request_access(...) enforces optional operator auth
  • robust Basic auth parsing and safe denial responses via AccessDeniedError
• App middleware added in src/transcription/app.py:
  • enforces auth on protected paths
  • returns consistent 401 envelope and WWW-Authenticate: Basic for denied requests
• Health endpoint /healthz remains intentionally unauthenticated.

3) Input validation and safe-output hardening

Completed baseline.

• src/transcription/services/upload.py
  • added size-based validation guard (max_upload_bytes)
  • emits user_input_error with actionable guidance on over-limit uploads
• src/transcription/errors.py
  • classify_unexpected_error(...) now returns operation-only message without embedding raw exception text
  • preserves traceability via existing error_id and taxonomy while reducing accidental sensitive leak risk

4) Secret handling and configuration safety

Completed baseline.

• src/transcription/config.py additions:
  • max_upload_bytes (default 15 * 1024 * 1024)
  • operator_access_enabled (default False)
  • operator_username (default operator)
  • operator_password (optional, required when auth enabled)
• Added settings validator enforcing fail-fast config safety:
  • raises validation error if OPERATOR_ACCESS_ENABLED=true and OPERATOR_PASSWORD unset
• README.md updated with Step 5 security env settings and explicit secret-handling guidance.

5) Dependency/security scanning baseline

Completed.

• Dependency vulnerability scan:
  • uvx pip-audit
  • Result: No known vulnerabilities found
• Static security scan:
  • uvx bandit -r src/transcription
  • Result: No issues identified (0 low/medium/high)

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Test and Verification Evidence

Added/Updated Tests

1. tests/api/test_access_control.py
   • unauthorized protected API denied (401 + challenge)
   • invalid credentials denied
   • valid credentials accepted
   • /ui protected when auth enabled
   • /healthz remains unprotected
2. tests/services/test_upload.py
   • added rejection test for payloads above MAX_UPLOAD_BYTES
3. tests/test_config.py
   • added security defaults assertions
   • added fail-fast assertion for missing OPERATOR_PASSWORD when auth enabled
4. tests/test_errors.py
   • updated expectations for sanitized unexpected-error message behavior
5. Updated integration expectations where failure detail should no longer include raw exception text:
   • tests/services/test_worker.py
   • tests/integration/test_pipeline_flow.py
6. tests/test_app.py updated for new middleware wiring.

Validation Runs

Run and record outcomes:

• uv run pytest --collect-only -q -> passed
• uv run pytest -m unit -q -> passed
• uv run pytest -m "not external" -q -> passed
• uv run pytest -q -> passed

Security Scan Evidence

Record scan commands and outcomes:

• dependency scan command(s): uvx pip-audit
• static/security lint command(s): uvx bandit -r src/transcription
• critical/high findings: none
• remediation/defer decisions: no remediations required for Step 5 baseline

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Requirement Traceability (Step 5)

Step 5 Area	REQ Coverage	Status	Evidence
Private-network and single-operator safety posture	REQ-9	met	docs/ver1/ver1-step5-security-assumptions.md, README security section
Access control behavior at UI/API boundaries	REQ-5, REQ-7	met	src/transcription/security.py, src/transcription/app.py, tests/api/test_access_control.py
Input validation and safe user-facing error behavior	REQ-1, REQ-2, REQ-5	met	src/transcription/services/upload.py, src/transcription/errors.py, updated tests
Config and startup safety controls	REQ-8, REQ-10	met	src/transcription/config.py, tests/test_config.py, README.md
Persistence and domain integrity continuity	REQ-11, REQ-12	met (no regressions)	full test lane pass including integration and worker flows

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Operational Artifacts Produced

• docs/ver1/ver1-step5.md
• docs/ver1/ver1-step5-results.md
• docs/ver1/ver1-step5-security-assumptions.md
• src/transcription/security.py
• tests/api/test_access_control.py

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Risks, Exceptions, and Follow-Ups

1. Basic auth is intentionally right-sized for trusted private-network use; if deployment posture changes, stronger identity controls are required.
2. Current model remains single shared operator credential (no per-user audit identity).
3. No built-in brute-force/rate-limit controls in Step 5 scope; evaluate in future hardening if threat model expands.

Open follow-ups to carry forward:

• Consider stronger auth/session model if system becomes multi-user or internet-accessible.
• Consider request throttling/rate limiting if threat model changes.

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Step 5 Exit Assessment

• Private-network assumptions and controls: met
• Access-control baseline effectiveness: met
• Validation and safe-output safety: met (baseline)
• Secret handling and config safety: met
• Dependency/security risk closure: met (no critical/high findings)
• Test and regression safety: met

Step 5 completion status: complete

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Handoff to Step 6

Once Step 5 is marked complete, Step 6 can proceed with:

• clearer operational security assumptions for logs/runbooks
• hardened boundary behavior for diagnosis and support
• reduced risk posture for personal-scale ongoing operations