Locksmith

Cross-platform software license validation backend. Supports online activation via a REST API and fully offline validation via signed license files. No frontend is provided — integrate against the API or ship the public key with your application.

License Fields

A license is composed of five independent dimensions. Each is validated separately; they can be combined freely to express any commercial licensing model.

Time

Controls how long the license is valid.

Value	Description
perpetual	No expiry date. Valid indefinitely from valid_from.
limited	Expires on expires_at. The duration is arbitrary — 1 month, 1 year, 3 years, etc.

Version

Controls which application versions the license covers.

Value	Description
any	Any version of the application is permitted.
maintenance	Only versions sharing the same major version as major_version are permitted. New major versions require a new or upgraded license.
specific	Only the exact version string in locked_version is permitted.

Edition

Controls which product editions are covered. editions is a list of case-insensitive strings. Leave empty to allow any edition. Common values:

home · pro · enterprise · server

Custom editions (e.g. "studio", "ultimate") are supported — the vendor defines the edition names; the client reports its edition at activation.

Host OS

Controls which operating systems the license is valid on. platforms is a list of case-insensitive strings. Leave empty to allow any platform.

Values can be broad or specific:

Example value	Meaning
windows	Any Windows version.
windows_server_2022	Windows Server 2022 only.
macos	Any macOS version.
linux	Any Linux distribution.

The client reports its platform string at activation. Naming is freeform — the vendor decides the convention; it is embedded and signed into the license.

Restriction

Controls how many simultaneous uses are permitted and how they are counted.

Mode	Field	Description
activations	activation_limit	Maximum number of distinct machines that may activate this license. Each machine is identified by its hardware-derived SHA-256 fingerprint.
users	user_limit	Maximum number of distinct named users (DOMAIN\username) that may be bound to this license.
floating	concurrent_limit	Maximum number of users or machines that may hold an active session concurrently. Check-out / check-in model.

Omit all limit fields (or set to null) to place no restriction on activations.

---

Entitlements

Entitlements allow a single license to govern multiple applications (bundles) with independent constraints per application. Each entitlement is matched by app_id and can specify its own edition, version, platform, and seat-count rules, overriding the license-level defaults for that application.

Field	Description
app_id	Reverse-domain identifier for the application (e.g. com.example.myapp).
editions	Allowed edition names for this app. Overrides the license-level editions.
min_version	Inclusive minimum app version (e.g. "2.0.0").
max_version	Inclusive maximum app version (e.g. "2.9.9").
platforms	Allowed host OS values for this app. Overrides the license-level platforms.
seats	Seat count override for this app. Falls back to the license-level limit if omitted.

A license with no entitlements applies to all applications unconditionally.

Bundle entitlements file (bundle.json) example:

[
  {
    "app_id": "com.example.editor",
    "editions": ["pro", "enterprise"],
    "min_version": "3.0.0",
    "seats": 5
  },
  {
    "app_id": "com.example.renderer",
    "platforms": ["windows", "linux"],
    "seats": 2
  }
]

---

Quick Start

1. Install

pip install -e ".[dev]"

2. Generate a keypair (server, once only)

locksmith-setup --out-dir keys

Keep keys/privkey.pem secret. Distribute keys/pubkey.pem with your application.

3. Configure

cp .env.example .env
# Set LOCKSMITH_ADMIN_API_KEY to a strong random value:
python -c "import secrets; print(secrets.token_hex(32))"

4. Start the server

locksmith-serve
# Listening on http://0.0.0.0:8000
# Interactive docs at http://localhost:8000/docs

5. Issue a license

# Perpetual, any version, any edition, any platform — no restriction
locksmith-issue --email user@example.com

# 1-year license, Pro or Enterprise editions, Windows and Linux, max 3 activations
locksmith-issue --email user@example.com \
  --expires-days 365 \
  --editions pro,enterprise \
  --platforms windows,linux \
  --activation-limit 3

# Maintenance — covers major version 2.x only, any platform, 5 activations
locksmith-issue --email user@example.com \
  --version-policy maintenance --major-version 2 \
  --activation-limit 5

# Floating — max 10 concurrent sessions
locksmith-issue --email user@example.com \
  --restriction floating --concurrent-limit 10

# Bundle — multiple applications from a JSON file
locksmith-issue --email user@example.com \
  --entitlements-file bundle.json

---

CLI Reference

Command	Description
locksmith-setup	Generate an RSA keypair for the license server.
locksmith-issue	Sign and issue a .lic license file. Accepts a customer .lsreq file to skip manual entry.
locksmith-verify	Verify a .lic file offline using only the public key (development / support tool).
locksmith-request	Run on the customer's machine to generate a .lsreq request file to send to the vendor.
locksmith-serve	Start the FastAPI license server.

API Endpoints

Method	Path	Auth	Description
GET	/health	None	Liveness probe.
POST	/licenses	Admin	Issue a new license; returns the raw .lic JSON.
GET	/licenses/{id}	Admin	Retrieve license metadata, entitlements, and usage counts.
DELETE	/licenses/{id}	Admin	Revoke a license immediately.
POST	/activate	None	Online activation — verifies the license and records the machine or user against the appropriate limit.
POST	/validate	None	Offline validation — accepts a .lic file upload and returns a verification result.
POST	/request	None	Accept a customer .lsreq file and queue it for vendor review.

POST /activate fields: license_id, machine_id, app_id, app_version, edition (optional), platform (optional).

POST /validate form fields: file (.lic), app_version, app_id, edition, platform — all optional except file.

Admin routes require Authorization: Bearer <LOCKSMITH_ADMIN_API_KEY>.

---

Offline Flow

1. Customer runs locksmith-request on their machine → produces customer.lsreq
2. Customer sends customer.lsreq to the vendor
3. Vendor runs locksmith-issue --request-file customer.lsreq → produces license.lic
4. Vendor sends license.lic back to the customer
5. Customer places license.lic in the application directory
6. Application calls validate_license(License.from_file("license.lic"), signer, ...) — fully offline

Note: Revocation and floating seat check-in/check-out require a network connection. Offline licenses rely on expiry as the revocation backstop.

---

Extending to KMS

FileSigner (local PEM files) implements the BaseSigner abstract interface in locksmith/core/keys.py. To use AWS KMS, HashiCorp Vault, or any other signing backend, implement BaseSigner.sign() and BaseSigner.verify() and pass your implementation to create_app() via app.state.signer.

Running Tests

pytest --cov=locksmith