White Paper
Encryption and Redaction in Oracle Database 12c
with Oracle Advanced Security
MARCH 2017
Table of Contents
Preventing Database Bypass with Encryption
Oracle Advanced Security Transparent Data Encryption
Protecting Sensitive Data Using TDE Column Encryption
Protecting Entire Applications Using TDE Tablespace Encryption
Protecting the Database Using TDE Database Encryption
Performance Characteristics
Built-In Key Management
Encryption Impact for Common Operational Activities
Limiting Sensitive Data Exposure with Data Redaction
Oracle Advanced Security Data Redaction
Policies and Transformations
Performance Characteristics
Security Considerations
Easy to Deploy Data Redaction
Comparison to Alternative Approaches
Applying Encryption and Redaction in Oracle Multitenant Architecture
Rising security threats, expanding compliance requirements, consolidation, and cloud computing are
just a few of the reasons why data security has become critical. Nearly 10 years after the first U.S.
breach notification law, the need for strong preventive controls continues to increase as access to data
expands. Initiatives such as the European Union’s General Data Protection Regulation (GDPR) help
ensure data security remains a top priority for organizations. Stolen client devices, including tablets
and smartphones, have the potential to easily expose sensitive information as users move beyond the
laptop. Outsourcing, offshoring, corporate mergers, and nearly continuous organizational change
create additional risks by making it easier for malicious insiders to obtain sensitive data and for outside
hackers to gain access to servers using social engineering attacks. These growing trends are just one
reason why centralized and efficient protection of sensitive data, regardless of the applications being
used, is more important than ever. Implementing security measures that consistently protect sensitive
data at the source becomes a critical control as stored data continues to proliferate and access to data
expands beyond traditional boundaries. Protecting data requires a defense in depth, multi-layered
approach that encompasses controls to evaluate security postures, prevent data loss, detect
suspicious activities and apply data access controls at the source through data-driven security. Oracle
Database 12c Release 2 strengthens Oracle’s industry leading database security solution by providing
important new security measures in each of these areas.
Oracle Advanced Security option with Oracle Database 12c delivers two essential preventive controls
covering encryption of data-at-rest and redaction of sensitive data displayed by applications. These
controls help protect sensitive data from being exposed directly from storage or through applications.
Oracle Advanced Security Transparent Data Encryption (TDE) helps prevent attacks that attempt to
bypass the database and read sensitive information from data files at the operating system level, from
database backups, or from database exports. Oracle Advanced Security Data Redaction
complements TDE by redacting sensitive data in query results before the data leaves the database,
thus reducing the risk of unauthorized data exposure in applications. This white paper describes TDE
and Data Redaction and explains how these valuable preventive controls can work together to help
secure your sensitive data.
Preventing Database Bypass with Encryption
Data-at-rest encryption is an important control for blocking unauthorized access to sensitive data using methods that
circumvent the database. Privileged operating system accounts are just one of the vehicles used by attackers and
malicious insiders to gain access to sensitive information directly in physical storage.
Oracle Advanced Security Transparent Data Encryption (TDE) stops attackers from bypassing the database and
reading sensitive information from storage by encrypting data in the database layer. Applications and users
authenticated to the database continue to have access to application data transparently, while unauthenticated
users attempting to circumvent the database are denied access to clear text data. To understand this better,
consider the fact that privileged operating system users can access database tablespace files and extract sensitive
data using simple shell commands. In addition, consider the possibility of attacks that read sensitive data from lost,
stolen, or improperly decommissioned disks or backups. Figure 1 shows an example of extracting customer credit
card numbers directly from storage using the common Linux “strings” command and a search pattern.
Figure 1. Extracting customer credit card numbers from Oracle database tablespace files
Oracle Advanced Security Transparent Data Encryption
Transparent Data Encryption resides at an optimal layer within the database to prevent database bypass while
maintaining application transparency. TDE deploys quickly and encrypts individual application table columns,
application tablespaces, or entire databases. It is transparent to applications because the encryption and decryption
processes do not require any application changes, and the application users do not have to directly deal with
encrypted data. Most importantly, TDE’s built-in two-tier encryption key management provides full key lifecycle
management, tracking the keys across their lifetime with helpful meta-data attributes, and assisted encryption key
rotation, switching to a new master key with no downtime. Figure 2 shows how encrypting an Oracle database
using TDE prevents database bypass.
Figure 2. Encrypting with Transparent Data Encryption to prevent database bypass
TDE is unique when compared to alternative approaches that encrypt entire storage volumes or require new toolkits
and programming APIs. These approaches do not protect against many bypass attacks, may require significant
application changes, have complex key management, and are not integrated with complementary technologies such
as Oracle Advanced Compression, Oracle Real Application Cluster (RAC), Oracle Recovery Manager (RMAN),
Oracle Multitenant, Oracle GoldenGate, and Oracle Active Data Guard.
The high level of protection provided by TDE follows common standards for strong encryption as described in the
figure below. With Oracle 12c Release 2, TDE supports operation with a FIPS 140-2 Level 1 cryptographic module,
using approved encryption suites for SSL/TLS and TDE encryption.
Encryption Algorithms
Hashing Algorithms (optional)
Advanced Encryption Standard (AES)
Secure Hash Algorithm 1 (SHA-1)
Key length: 128, 192, 256 bits
Digest length: 160 bits
Triple Data Encryption Standard (TDES)
Key length: 168 bits
Regional encryption algorithms
Figure 3. Standard encryption and hashing algorithms used by TDE
Protecting Sensitive Data Using TDE Column Encryption
Oracle Advanced Security TDE column encryption can be used to encrypt specific data in application tables such as
credit card numbers and U.S. Social Security numbers. Customers identify columns within their application schema
containing sensitive or regulated data, and then encrypt only those columns. This approach is useful when the
database tables are large, only a small number of columns must be encrypted, and the columns are known. TDE
column encryption also is useful for warehouse applications where each query is likely to return a very different set
of data. Oracle Enterprise Manager Sensitive Data Discovery searches for and identifies sensitive columns quickly.
Data encrypted using TDE column encryption remains encrypted on backup media and discarded disk drives,
helping prevent unauthorized access and potential data breaches that bypass the database.
Protecting Entire Applications Using TDE Tablespace Encryption
Oracle Advanced Security TDE tablespace encryption protects entire application tables by encrypting the underlying
tablespaces. It encrypts application tablespaces regardless of the data’s sensitivity and irrespective of its data type.
Tablespace encryption simplifies the encryption process because there is no need to identify specific database
columns. It is useful when the database contains a large amount of sensitive data to be encrypted and the columns
reside in many different locations. TDE tablespace encryption and TDE column encryption can be used
independently of one another or together within the same database. As is the case with both TDE column
encryption and TDE tablespace encryption, data remains protected on backup media as a measure against potential
bypass attacks.
Protecting the Database Using TDE Database Encryption
Oracle Advanced Security TDE database encryption protects entire databases including Oracle-supplied
tablespaces SYS, SYSAUX, TEMP and UNDO. A new capability with Oracle 12c Release 2, this approach ensures
that sensitive system and metadata information remain protected through encryption as well as application data.
Performance Characteristics
TDE’s cryptographic operations are extremely fast and well integrated with related Oracle Database features. TDE
leverages CPU-based hardware cryptographic acceleration available in Intel® AES-NI and Oracle SPARC T4/T5
platforms to increase performance by up to 5x or more. The block-level operations of TDE tablespace encryption
receive an additional performance boost from database buffering and caching. Tablespace encryption integrates
seamlessly with Oracle Advanced Compression, ensuring that compression occurs before encryption. Tablespace
encryption also integrates with the advanced technologies in Oracle Exadata such as Exadata Hybrid Columnar
Compression (EHCC) and Smart Scans, which offload certain cryptographic processing to storage cells for fast
parallel execution.
Built-In Key Management
Key management is critical to the security of the encryption solution. Oracle Advanced Security TDE provides an
out-of-the-box, two-tier key management architecture consisting of data encryption keys and a master encryption
key. The data encryption keys are managed automatically by the database and are in-turn encrypted by the master
encryption key. The master encryption key is stored and managed outside of the database within an Oracle Wallet,
a standards-based PKCS12 file that protects keys, or in Oracle Key Vault, a centralized key management platform.
Keeping the master key separate from the encrypted data mitigates attacks because both the keys and the
encrypted data must be separately compromised to gain access to clear data. The two-tier key architecture also
enables rotation of master keys without having to re-encrypt all of the sensitive data. Oracle Advanced Security
defines a dedicated SYSKM role that may run all key management operations including rotating master keys and
changing the keystore password. This role can be optionally delegated to a designated user account to enable
separation of duty for these functions. Oracle Enterprise Manager provides a convenient graphical user interface for
creating, rotating, and managing TDE master keys as shown in the figure below.
Oracle Key Vault is a full-stack, security-hardened software appliance which provides centralized management of
encryption keys, Oracle Wallets, Java Keystores, and credential files. Oracle Key Vault works with TDE to automate
the management of TDE master keys including creation, rotation, and expiration. Oracle Key Vault itemizes and
stores the contents of Oracle Wallets in a master repository where they can be recovered back to servers if their
local copies are mistakenly deleted or their passwords are forgotten. In addition, Oracle Key Vault can centrally
manage TDE master keys over a direct network connection as an alternative to using local wallet files, eliminating
operational challenges of wallet file management such as periodic password rotation, wallet file backups, and wallet
file recovery. Using Oracle Key Vault with TDE enables sites to scale their TDE deployments to hundreds or
thousands of databases while improving operational efficiencies, reducing TCO, and enabling consistent key
management policies. Oracle Key Vault supports hybrid cloud deployments, so organizations migrating to the
Oracle Cloud can use it to support TDE deployments in both their cloud and on premises databases.
Figure 4. Managing and rotating TDE master keys using Oracle Enterprise Manager
Encryption Impact for Common Operational Activities
Essential day-to-day database operational activities can potentially leak sensitive data when not performed properly,
making bypass easy. Examples of these activities include database backup and restore, data movement, highavailability clustering, and replication.
Database Technologies
Example Points of Integration
High-Availability Clusters
Oracle Real Application Clusters (RAC), Data Guard, Active Data Guard
Backup and Restore
Oracle Recovery Manager (RMAN), Oracle Secure Backup
Export and Import
Oracle Data Pump Export and Import
Database Replication
Oracle Golden Gate
Pluggable Databases
Oracle Multitenant Option
Engineered Systems
Oracle Exadata Smart Scans
Storage Management
Oracle Automatic Storage Management (ASM)
Data Compression
Oracle Standard, Advanced , and Hybrid Columnar Compression
TDE Support
Figure 5. Example integrations with Oracle Advanced Security TDE
Oracle Advanced Security TDE supports these critical database operational activities and helps ensure that the data
remains encrypted. Tablespace encryption integrates with Oracle Recovery Manager (backup and restore), Oracle
Data Pump (data movement), Oracle Active Data Guard (redundancy and failover), and Oracle Golden Gate
(replication). TDE also integrates with internal features of the database such as redo to prevent possible data
leakage in logs. This fully integrated approach to database encryption makes the solution easy to deploy in complex
real-world environments, while protecting against bypass attacks that attempt to take advantage of gaps in
operational processes.
Oracle Database 12c Release 2 TDE provides two options for performing tablespace conversions from clear-text to
encrypted tablespaces. For deployments which require conversion to be performed with no downtime, online
tablespace encryption runs in the background to convert tablespaces from clear text to encrypted text while systems
remain operational. TDE also offers an offline tablespace conversion mode which efficiently converts tablespaces
with no storage overhead.
Limiting Sensitive Data Exposure with Data Redaction
Privacy and compliance require a cost effective approach to managing data exposure in applications. The embrace
of smartphone and tablet devices make the issue of sensitive data exposure even more urgent as data access
beyond the traditional office environment becomes commonplace. Even traditional applications require a more
comprehensive solution for reducing exposure to sensitive data, for example a call center application with a screen
that exposes customer credit card information and personally identifiable information to call center operators.
Exposing that information, even to valid application users, may violate privacy regulations and put the data at
unnecessary risk.
Figure 6. Clear and redacted information displayed in a call center application
Oracle Advanced Security Data Redaction
Oracle Advanced Security Data Redaction provides selective, on-the-fly redaction of sensitive data in database
query results prior to display by applications so that unauthorized users cannot view the sensitive data. The stored
data remains unaltered, while displayed data is transformed and redacted on-the-fly before it leaves the database.
Data Redaction reduces exposure of sensitive information and helps prevent exploitation of application flaws that
may disclose sensitive data in application pages. It is well suited for both new and legacy applications that need to
limit exposure of sensitive data without invasive application changes.
Figure 7. Redacting sensitive data displayed by applications using Data Redaction
Policies and Transformations
Oracle Advanced Security Data Redaction supports a number of different transformations that can redact all data in
specified columns, preserve certain pieces of the data, or randomly generate replacement data. Examples of the
supported data transformations are shown below.
Figure 8. Example Data Redaction transformations
Data Redaction makes the business need-to-know decision based on declarative policy conditions that utilize rich
runtime contexts available from the database and from the applications themselves. Examples include user
identifiers, user roles, and client IP addresses. Context information available from Oracle Application Express
(APEX), Oracle Real Application Security, and Oracle Label Security also can be utilized to define redaction policies.
Redacting APEX applications is straightforward because policy conditions can leverage the application users and
application identifiers that APEX automatically tracks. Multiple runtime conditions can be joined together within a
data redaction policy for fine-grained control over when redaction occurs. The policies are stored and managed
inside of the database, and they go into effect immediately upon being enabled.
Performance Characteristics
High-speed performance is crucial for Data Redaction because the target databases typically will be production
systems. Data needs to be transformed on-the-fly at runtime, without altering data stored on disk or in caches and
buffers. Because the transformations will execute on production environments and will be repeated frequently, the
performance overhead must be small.
One important performance characteristic of Data Redaction is that it supports only data transformations with proven
high performance. These are a subset of all the possible operations that could be used to transform data in nonproduction environments. This specific subset avoids long running and processor intensive operations.
Data Redaction also leverages performance optimizations of the Oracle Database that are only possible by being
part of the database kernel. The implementation ensures that data transformations are fast in-memory
computations. Policy information is cached in memory, and policy expressions are evaluated only once per
execution, so there is no per row performance impact.
Security Considerations
Another benefit resulting from Data Redaction being part of the database kernel is tighter security. This
implementation avoids potential vulnerabilities that plague other redaction techniques due to their dependence on
proxies that can be meddled with. Additionally, Data Redaction in the kernel continues protecting sensitive data
even when other security measures may be compromised. For example, runtime conditions in policies can narrow
the impact of a SQL Injection attack by continuing to redact sensitive data even when the attack has bypassed other
preventive controls in the application and database.
Data Redaction also avoids obvious sources of leakage where the redaction policy could be bypassed by copying
data into a new table that does not have a policy. Certain mass copy operations that touch redacted data are
blocked by default, and this behavior can be overridden where necessary using a Data Redaction exempt privilege.
Although Data Redaction can be used to prevent accidental viewing of sensitive data by privileged database users
such as DBAs, it is intended primarily for redacting data displayed by software applications. Data Redaction does
not prevent privileged users from connecting directly to the database and running ad hoc queries that back into
pieces of sensitive data (i.e. it does not stop exhaustive ad hoc queries or other inference attacks). However, Data
Redaction is fully compatible with Oracle Database security solutions that control and monitor privileged database
user access, including DBAs. It can be deployed in tandem with other solutions such as Oracle Database Vault or
Oracle Audit Vault and Database Firewall to provide defense-in-depth security. Data Redaction can also be used
with database encryption as well, and it is a great complement to TDE.
Easy to Deploy Data Redaction
Data Redaction can be deployed for existing applications quickly using either a command line API or Oracle
Enterprise Manager. The command line API is a PL/SQL procedure that accepts protected columns, transformation
types, and conditions. Oracle Enterprise Manager provides a convenient Policy Expression Builder that enables
administrators to define and apply redaction policies on existing applications. As shown below, the Policy
Expression Builder dialog guides the user through creating policy conditions that use context obtained from
applications, the database, the APEX framework, and other database security solutions.
Figure 9. Using Oracle Enterprise Manager Policy Expression Builder to create Data Redaction policies
Predefined column templates also are available in Oracle Enterprise Manager for redacting common sensitive data
such as credit card numbers and U.S. Social Security numbers. Oracle Enterprise Manager Sensitive Data
Discovery assists in locating columns to be redacted inside of complex application schemas.
Another reason why Data Redaction is easy to deploy is its transparency to applications and the database. For
application transparency, Data Redaction supports the column data types that are frequently used by applications
and various database objects including tables, views, and materialized views. Redacted values retain key
characteristics of the original data such as the data type and optional formatting characters. Random redaction
values are drawn from data ranges defined by the existing column data. For transparency to the database, Data
Redaction avoids impacting essential database operational activities. It does not affect administrative tasks such as
data movement (Oracle Data Pump) or database backup and restore (Oracle Recovery Manager). It does not
interfere with database cluster configurations such as Oracle Real Application Clusters, Oracle Active Data Guard,
and Oracle GoldenGate. Data Redaction does not get in the way of existing database triggers or Oracle Virtual
Private Database (VPD) policies. And because Data Redaction is part of the database kernel, no separate
installation is required.
Comparison to Alternative Approaches
Traditional approaches to redacting sensitive data typically relied on application coding or installing third-party
software on the database server to modify its behavior. These alternatives have important drawbacks compared to
Data Redaction.
Approaches that require coding new application logic, modifying existing SQL statements, or authoring custom
application scripts are likely to result in disparate solutions that are inconsistent across the enterprise and costly to
maintain over their lifetime. In addition, strict controls must be placed on new application development to make sure
that custom application code and new objects are properly accessed. The code also needs to take into
consideration multiple factors under which the redaction policies are enforced, while maintaining the performance
and semantics of the application.
Approaches that add new components to the Oracle Database, overwrite existing components, establish proxies,
and modify basic behavior of the database also are fraught with problems. Not only do the new components
introduce new attack surfaces, but they also can create performance overhead, impact operational activities of the
database, and may fail when attempting to transform complex database queries that are generated by applications.
In contrast, redacting directly in the Oracle Database kernel using Data Redaction has tighter security, superior
performance, and better compatibility with a range of database configurations, use cases, and workloads.
Applying Encryption and Redaction in Oracle Multitenant Architecture
Oracle Advanced Security fully supports the Oracle Database 12c multitenant architecture. Both TDE and Data
Redaction attributes automatically follow Pluggable Databases (PDB) as they move between multitenant Container
Databases (CDB). When moving a PDB that has redaction policies, the policies transfer directly to the new
container as part of the PDB. When moving an encrypted PDB, the TDE master keys for that PDB are transferred
separately from the encrypted data to maintain proper security separation during transit. Encryption and redaction
immediately resume their normal operation after the PDB has been plugged in and configured.
As data exposed in applications continues to rapidly expand, enterprises must have strong controls in place to
protect data no matter what devices or applications are used. Oracle Database 12c Release 2, now available in the
cloud and on-premises, helps organizations keep their sensitive information safe in this increasingly complex
environment by delivering critical controls that enforce data security in the database.
Oracle Advanced Security with Oracle Database 12c Release 2 provides two critical preventive controls.
Transparent Data Encryption encrypts data at rest to stop database bypass attacks from accessing sensitive
information in storage. Data Redaction reduces exposure of sensitive information in applications by redacting
database query results on-the-fly, according to defined policies. Together these two controls form the foundation of
a multi-layered, defense-in-depth approach. They further establish Oracle Database 12c Release as the world’s
most advanced database solution
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Encryption and Redaction in Oracle Database 12c with Oracle Advanced Security
March 2017
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