TDE -> Transparent Data Encryption

TDE stands for Transparent Data Encryption.TDE provides an additional layer of security by encrypting sensitive data and protecting it from unauthorized access.

Some of the features:

• Encryption Types: Column level,tablespace level 
• Transparent Encryption and Decryption:
• Key Management: TDE uses a master encryption key to encrypt and decrypt the data using oracle wallet 
• Database-Level Encryption: TDE encrypts data at rest
• Compliance and Security:PCI(payment card Industry), HIPAA

column level:
=========== 
-- Create the table with the column to be encrypted
CREATE TABLE customer_data (
  customer_id NUMBER,
  credit_card_number VARCHAR2(16),
  -- other columns
);

-- Encrypt the 'credit_card_number' column
BEGIN
  DBMS_CRYPTO.ENCRYPT(
    src => DBMS_CRYPTO.HASH_SH1,
    key => 'encryption_key',
    typ => DBMS_CRYPTO.ENCRYPT_AES256
  );
  DBMS_CRYPTO.ENCRYPT(
    typ => DBMS_CRYPTO.ENCRYPT_AES256,
    key => 'encryption_key',
    src => customer_data.credit_card_number,
    dst => customer_data.credit_card_number_encrypted
  );
END;
/

Tablespace level:

-- Create a tablespace with encryption
CREATE TABLESPACE encrypted_ts
  DATAFILE '/path/to/encrypted_ts.dbf'
  SIZE 100M
  ENCRYPTION USING 'AES256' DEFAULT STORAGE(ENCRYPT);

key management:

-- Create a new encryption key
ALTER SYSTEM SET ENCRYPTION KEY IDENTIFIED BY "encryption_password" FOR all USERS;


database level
-- Enable encryption for an existing tablespace

ALTER TABLESPACE data_ts   ENCRYPTION ONLINE;