Envelope Encryption.

A pattern in which bulk data is encrypted by a fast data encryption key, which is itself encrypted (wrapped) by a master key stored in a KMS or HSM. It belongs to the Cryptography category of cybersecurity.

A pattern in which bulk data is encrypted by a fast data encryption key, which is itself encrypted (wrapped) by a master key stored in a KMS or HSM.

Envelope encryption decouples bulk symmetric encryption from key custody. A per-object Data Encryption Key (DEK) - typically a fresh AES-256 key - encrypts the payload, then the DEK is itself encrypted by a long-lived Key Encryption Key (KEK), also called the master key, that never leaves a KMS or HSM. Only the wrapped DEK is stored alongside the ciphertext; decryption requires a KMS call that unwraps the DEK under proper IAM controls. This pattern enables fast local encryption, fine-grained per-tenant or per-record keys, cheap key rotation (rewrap the DEK, not the data), and clean audit trails. It is the basis of AWS KMS, Google Cloud KMS, S3 SSE-KMS, and most cloud storage encryption.

Defences for Envelope Encryption typically combine technical controls and operational practices, as detailed in the full definition above.

Common alternative names include: Wrapped key encryption, DEK/KEK pattern.