Oracle's Transparent Data Encryption (TDE) is a pivotal feature for securing sensitive information in your database. It offers robust encryption for data stored in tables, tablespaces, and backups, ensuring that unauthorized users cannot access your critical data. TDE relies on external security modules, known as TDE wallets or keystores, to manage and protect encryption keys.
Understanding TDE Configuration and Usage
To set up TDE, you'll need the "Administer Key Management" privilege or SYSKM administrative rights. However, these privileges are not required for routine use of TDE. TDE supports various Advanced Encryption Standard (AES) cipher keys, including 128, 192, or 256 bits, allowing for flexible and secure encryption settings.
TDE encrypts all data within an encrypted tablespace, including redo logs, but does not cover data stored outside the tablespace, such as BFILE data.
Two-Tiered Encryption Architecture
TDE employs a two-tiered key architecture for both tablespace and column encryption. The TDE master key, which is crucial for the encryption and decryption processes, is securely stored in an external keystore. This keystore could be an Oracle Wallet, Oracle Key Vault, or Oracle Cloud Infrastructure (OCI) Key Management Store (KMS).
For column-level encryption, the master key is also stored in an external keystore. The Oracle Wallet, which uses the PKCS#12 standard, secures certificates and encryption keys. This wallet is encrypted with an AES256 key derived from the TDE wallet password.
A unique feature of Oracle TDE is its ability to maintain a history of retired master encryption keys. This capability allows for key rotation while still being able to decrypt data encrypted with earlier keys. In Real Application Clusters (RAC), it is important to store the keystore in ASM or Oracle ACFS, as individual TDE wallets per RAC instance are not supported.
Types of Keystores
Oracle offers two categories of keystores:
1. Software Keystores
- Auto-login TDE Wallets: These wallets, protected by a system-generated password, open automatically at database startup. Ideal for environments requiring minimal manual intervention, such as Oracle Data Guard standby databases.
- Local Auto-login TDE Wallets: These are created locally on the machine and cannot be transferred to other systems. They provide additional security but are not suitable for RAC databases.
- Password-Protected TDE Wallets: These require a password for access and must be manually opened before any keys can be used.
2. External Key Managers
- Oracle Key Vault: A centralized, secure solution for key management.
- OCI Vault: Oracle Cloud Infrastructure’s key management service
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