Context
Some models at EnergyYar contained sensitive data whose integrity needed protection. My résumé records implementing an HMAC-based Data Integrity Mixin to help detect tampering.
Engineering work
The implementation connected data integrity protection to the model layer. The available record establishes the HMAC-based approach, but does not specify the internal serialization, key storage, rotation policy, or model fields.
What HMAC establishes
A message authentication code can detect modification when verification uses the expected message and shared secret. It does not encrypt data, establish user authorization, or address a compromised secret. These are properties of the technique, not claims about undocumented internal controls.
Explore the principle
The Data Integrity Playground provides an independent browser-based HMAC-SHA256 demonstration with a stated serialization scheme. It uses sample data and is not a copy of employer code.