Oracle Transparent Data Encryption (TDE) 12c is an advanced security feature that encrypts data-at-rest, protecting it from unauthorized access, particularly for sensitive tables and columns. The setup involves creating an Oracle wallet to store the TDE master key and following specific steps to encrypt targeted data. While TDE provides options for both column and tablespace encryption, it has limitations including overhead costs and restrictions on index types.

1. Oracle Transparent Data
Encryption (TDE) 12c
Prepared by @nabeelxy
8/30/2014

2. Typical Deployment of Databases
Users Applications
DBA
DB server DB files

3. Attack Surface
Users Applications
DBA
DB server DB files

4. Direct Access to Data
Users Applications
DBA
DB server DB files

5. What is TDE?
• An Oracle advanced security feature that
allows to encrypt data-at-rest completely
transparent to applications
• It is not an access control mechanism for
Oracle database users
• Notice that the data is encrypted only at rest –
when the database server processes the data
in the SQL layer, data records are decrypted
and processed

6. Why TDE/Encryption?
• If attackers can gain access to the operating
system as a powerful user (e.g. root or oracle),
they can bypass the database and have direct
access to data. Encryption can protect
database files stored in the disk
• Also, many regulatory compliance requires
encrypting data at rest

7. Encryption Options Available
• DBMS_CRYTO – client side encryption
• TDE
– Column encryption (10gR2 onwards)
– Tablespace encryption (11gR1 onwards)
• In this presentation, we only look at TDE

8. TDE Setup
Name Salary Position
#$%34dfa*(a x9@#!3 Manager
*#%!@sx*da A#&2uz Engineer
$23%&T&df %x!9zTu Analyst
^31%&T*z9a Xy&*x90 Engineer
Master key
Oracle Data Dictionary
Oracle Wallet
emp table
hr tablespace
table1
table2
index
1
seq1
Oracle database

9. TDE Workflow
1. Setup wallet and master key
2. Identify
– Tables with sensitive columns
– Tablespaces with sensitive tables
3. Open wallet
4. Encrypt
– The identified columns
– The identified tablespaces
5. Close wallet

10. Oracle Wallet
• A PKCS#12 formatted file residing outside of
the database (residing in the file system)
• Encrypted using password based encryption
as defined in PKCS#5
• Holds the TDE master key
• It is a good practice to setup the wallet
outside of the $ORACLE_BASE and grant
minimal privileges to the wallet folder

11. Setting up Oracle Wallet
• Specify wallet location using the sqlnet.ora
ENCRYPTION_WALLET_LOCATION:
ENCRYPTION_WALLET_LOCATION=
(SOURCE=(METHOD=FILE)(METHOD_DATA=
(DIRECTORY=/etc/orcl/keystore)))
• Initialize and create the master key in SQL*PLUS
in CDB$ROOT:
ADMINISTER KEY MANAGEMENT CREATE KEYSTORE
'/etc/orcl/keystore’ IDENTIFIED BY password;
• This creates a file called ewallet.p12 in the wallet
folder

12. Opening the Wallet
• Once the wallet is open, the master key
becomes available to the database
ADMINISTER KEY MANAGEMENT
SET KEYSTORE OPEN IDENTIFIED BY chia_123
CONTAINER = ALL;
• Once the wallet is open, you can perform TDE
operations
– Column encryption
– Tablespace encryption
• v$encryption_wallet view shows the wallet
status

13. Opening the Wallet
• select wrl_parameter, status, con_id from
v$encryption_wallet;
WRL_PARAMETER STATUS CON_ID
------------------ ---------- ------
/etc/orcl/keystore OPEN 0
• In order to exercise least privilege and separation
of duty constraints, it is recommended to use a
SYSKM user instead of a SYSDBA to perform
wallet management

14. Two-Tier Key Architecture
• Master key is stored in an Oracle Wallet
(keystore)
• Tablespace or table (column) keys are stored
in the database itself in the Oracle data
dictionary – they are encrypted using the
master key
• If HSM is used for the Oracle Wallet, master
key is not fetched to the database to decrypt
the tablespace/table keys

15. TDE Column Encryption
• Allows to encrypt one or more columns of a
table
• Each column is assigned a unique symmetric
key
• The symmetric keys are stored encrypted
using the master key in the Oracle data
dictionary (in sys.enc$ table)

16. TDE Column Encryption
• Create encemp table with two encrypted
columns
create table encemp (
name varchar2(128) encrypt,
salary number(6) encrypt,
position varchar2(32)
);
• user_encrypted_columns view shows
the encrypted columns
TABLE_NAME COLUMN_NAME ENCRYPTION_ALG
--------------- --------------- ------------------
ENCEMP NAME AES 192 bits key
ENCEMP SALARY AES 192 bits key

17. TDE Column Encryption
• Can change encryption parameters, encrypt,
or decrypt table columns later using ALTER
TABLE statement.
• Can change both master key and table keys
– If master key is changed, no change to the
encrypted columns
– If table keys are changed, encrypted columns are
re-encrypted with the new keys

18. Limitations of Column Encryption
• Higher overhead than tablespace encryption
• Supports only B-tree indexes
• Foreign key columns cannot be encrypted
• Cannot perform range scans over encrypted
data
• Requires more storage

19. Tablespace Encryption
• Every object in the tablespace is encrypted
• Specify encryption parameters at the time of
tablespace creation
create tablespace encts
logging
datafile '?/dbs/encts.dbf'
size 32m
autoextend on
next 32m maxsize 2048m
default storage(encrypt)
• Note that you cannot encrypt existing
tablespaces

20. Tablespace Encryption
• You can view the encrypted tablespaces using
the dba_tablespaces view
TABLESPACE_NAME ENCRYPTED
--------------- ---------
SYSTEM NO
SYSAUX NO
TEMP NO
SYSEXT NO
ENCTS YES
• Use v$encrypted_tablespaces table to see the
encryption options set for encrypted
tablespaces

21. Re-Key Support
Release Column Encryption Tablespace Encryption
Master Key Table keys Master key Table keys
10gR2 Yes Yes N/A N/A
11gR1 Yes Yes No No
11gR2 Yes* Yes Yes* No
12cR1 Yes* Yes Yes* No
* Unified master key where both column and tablespace encryption
uses the same master key

22. Column vs. Tablespace Encryption
Column Encryption Tablespace Encryption
Column encryption is expensive; so, use it
only if less than 5% of all the application
table needs encryption
Use when most of the application data
are sensitive
Does not support hardware crypto
acceleration
Supports hardware crypto acceleration
Supports only B-tree indexes Does not have such a restriction
Support rekeying of data Does not support rekeying of data
Can encrypt existing tables Cannot encrypt existing tablespaces

23. References
• http://docs.oracle.com/database/121/ASOAG
/asotrans.htm