Envelope Encryption vs Field-Level Encryption vs Tokenization

Each technique answers a different question about where sensitive data lives.

Envelope encryption = whole files. What it protects: whole documents, files, and objects at rest. The file is encrypted with a unique DEK; the DEK is wrapped by a KEK. Even a full storage breach yields only ciphertext. Cost: you cannot query inside an encrypted file without decrypting it.

Field-level = specific columns. What it protects: specific columns or fields in a database — credit card numbers, national IDs, health data — while leaving the rest queryable. You can still search and filter on encrypted fields only with special techniques (deterministic encryption, blind indexes).

Tokenization = removes the value. What it protects: the sensitive value itself, by replacing it with a random token stored in a vault. The real value never lives in your application database or logs. If the database leaks, attackers get tokens with no meaning. But every lookup needs a vault round-trip.

The right technique depends on the data type, how it is used, and what your compliance regime demands.

Files and objects → envelope encryption. Choose envelope encryption when you store whole files or objects: signed PDFs, contracts, medical images, evidence packages. It is also the standard for cloud storage and KMS-managed object encryption. If you cannot query inside it, you usually do not need to.

Structured sensitive columns → field-level. Choose field-level encryption when you store structured records with a few highly sensitive columns: a signer database with national ID numbers, a CRM with payment details, a health record with diagnosis codes. You keep the row structure and queryability of everything else.

Identifiers & payment data → tokenization. Choose tokenization when the sensitive value is used mainly as an identifier or for transactions: payment card data (PCI DSS), account numbers, phone numbers in logs. Removing the value shrinks your compliance scope dramatically — the vault becomes the only place the real data exists.

Real systems use all three. Production systems typically combine all three: envelope encryption for stored documents and backups, field-level encryption for sensitive database columns, tokenization for card data — plus TLS for everything in transit. The question is never "which one," it is "which layer needs which."