GPG, or GNU Privacy Guard, is an open-source standard for encrypting data using public and private keys. Field-level encryption means you encrypt specific fields inside a record instead of the whole payload. This approach reduces exposure, limits blast radius, and makes compliance easier. The sensitive value is locked before it ever touches disk or leaves your control plane.
When records live in relational databases, NoSQL stores, or log streams, a breach often exposes full datasets. Field-level encryption makes pulled data meaningless without the private key. GPG uses asymmetric cryptography, so public keys encrypt, private keys decrypt. Even teammates with read access cannot see protected fields without explicit permission.
Implementation is straightforward. First, generate a GPG key pair. Next, decide which fields hold sensitive information — names, SSNs, payment data, API tokens. Use the public key to encrypt those fields before writing to the database. On read, authorized services use the private key to decrypt. Key management matters: store keys outside application repos, rotate them often, monitor usage.