This packages originated from https://github.com/facebook/relay. It verifies automatically generated files and effectively prevents from manual pollution. Usage (simplified GraphQL schema snapshoting example):

```rust // we can save a signed file let newsnapshot = signedsource::signfile(&format!("# {}\n\n{}", signedsource::SIGNING_TOKEN, schema))

// or verify its content signedsource::issigned(&oldsnapshot) signedsource::isvalidsignature(&old_snapshot) ```

It is also possible to re-sign file which is already signed (means update the signature when it already exists).