This blog was originally published in December of 2022 and updated in February of 2024.

Encrypting data at rest in a database management system (DBMS) refers to securing data by encrypting it when it is not being used or accessed. This is often done to protect sensitive data from unauthorized access or theft. With transparent data encryption (TDE), the encryption process is transparent to the user, allowing them to access and manipulate the data as usual without worrying about the encryption and decryption process. Depending on the organization’s specific security needs, TDE can be applied at various levels, such as at the database, column, or cell level. Implementing TDE can help ensure that sensitive data is protected and only accessible to authorized users with the proper decryption keys.

What is Transparent Data Encryption?

Transparent Data Encryption (TDE) serves as a security mechanism that encrypts data at the storage layer, protecting sensitive data contained in database files on disk. TDE encrypts and decrypts data on the fly as it is written to or read from the storage without requiring any modifications to the application’s code. This guarantees that data remains encrypted while at rest, offering a crucial security layer against unauthorized access, particularly in situations where physical security controls fail.

The idea of TDE has evolved significantly since its inception, becoming a standard component of database security strategies across various platforms. Originally designed to address growing concerns about data breaches and regulatory compliance, its evolution reflects the increasing sophistication of cyber threats and the necessity for comprehensive data protection methods that are transparent to end users and applications.

TDE provides a powerful way to protect sensitive data such as personal identification numbers, financial information, and other data, helping organizations meet legal and regulatory requirements for data protection.

What are the benefits of Transparent Data Encryption?

Transparent Data Encryption (TDE) is an effective data security solution, especially for companies that handle sensitive information. TDE provides multiple levels of protection by encrypting data at rest, guaranteeing that it is secure from unauthorized access. Let’s look at the key benefits of implementing TDE and how it contributes to a comprehensive security strategy.

Enhanced data security 

TDE greatly improves data security by encrypting database files on disk, making sensitive data inaccessible to unauthorized users. Even if attackers circumvent network security measures to get physical access to the storage media, the data is still secure since it is encrypted. This layer of encryption protects the data from breaches and theft.

Compliance with regulations 

Many industries are subject to stringent regulatory requirements that mandate the protection of sensitive data. TDE assists entities in adhering to such standards, including GDPR, HIPAA, and PCI DSS, through an uncomplicated approach to encrypting data at rest. Achieving compliance prevents legal repercussions and enhances customer confidence by showcasing an organization’s dedication to securing data.

Seamless integration 

One of TDE’s primary advantages is its ability to seamlessly integrate into current database environments without requiring application code changes. This ease of integration simplifies the encryption process, allowing organizations to use TDE without requiring significant modifications to their existing systems or affecting the end-user experience.

Centralized key management 

TDE provides a centralized approach to managing encryption keys, making their administration more straightforward. This method guarantees the secure storage and backup of keys, with access limited strictly to authorized staff, thus minimizing the chances of unintended key disclosure or misplacement. This centralized approach streamlines key lifecycle management, making it easier to enforce security policies and procedures.

Minimal performance impact 

Despite the additional layer of encryption, TDE is intended to have minimal impact on database performance. Modern encryption algorithms and hardware improvements make data encryption and decryption procedures efficient, allowing for secure data processing with minimal performance loss. This means that businesses can improve security without sacrificing system performance or user experience.

Understanding the different levels of encryption available

Encryption methods deploy multiple layers of defense to secure sensitive data against unauthorized breaches. Through the implementation of encryption at different tiers—such as disk, cluster, database, and table—organizations can tailor their security measures to align with their unique needs and the level of data sensitivity they oversee. A closer examination of each encryption layer reveals the mechanisms by which data is safeguarded under various conditions.

Disk-level encryption

Disk-level encryption is a security measure that encrypts all data stored on a disk or storage device. The level granularity only encrypts the full or partial disk. This is independent of the database, and external tools can be used to achieve this.

  • Disk-level encryption is a security measure that encrypts all data stored on a disk or storage device.
  • It ensures that the data is protected against unauthorized access and can only be accessed by authorized users with the proper decryption keys.
  • Disk-level encryption is often used to protect data at rest and can be implemented using full or partial disk encryption.
  • Several tools are available for implementing disk-level encryption, including BitLocker for Windows, dm-crypt for Linux, and FileVault for MacOS.

Cluster-level encryption

Cluster-level encryption is a security measure that encrypts data stored in a cluster of servers or storage devices. 

  • It ensures that the data is protected against unauthorized access and can only be accessed by authorized users with the proper decryption keys.
  • Cluster-level encryption can help protect data at rest and in motion when transmitted between servers in the cluster.
  • Several database management systems support cluster-level encryption, including Oracle, MySQL, Microsoft SQL Server, MongoDB, and Cassandra.

Database-level encryption

Database-level encryption is the encryption of the entire database or all data stored within the database. 

  • Database-level encryption is the encryption of an entire database or all data stored within the database.
  • It can provide a high level of security for sensitive data and is often used in conjunction with other security measures, such as TDE and cluster-level encryption.
  • Several database management systems support database-level encryption, including Oracle, MySQL, and Microsoft SQL Server.

Table-level encryption

Table-level encryption is a security measure that allows users to encrypt specific tables or columns within a database. It can provide a high level of security for sensitive data and is often used in conjunction with other security measures, such as TDE and cluster-level encryption. Here are some critical points about table-level encryption in a relational database management system.

  • Table-level encryption allows users to selectively encrypt specific tables or columns within a database rather than encrypting the entire database or all data stored within it.
  • It can provide a high level of security for sensitive data while still allowing users to access and manipulate it as usual.
  • Table-level encryption is often used with other security measures, such as TDE and cluster-level encryption, to provide a more comprehensive security solution.
  • Several RDBMSs, including Oracle, MySQL, and Microsoft SQL Server, support it.
  • Implementing table-level encryption may require additional resources and impact performance, so carefully evaluating the trade-offs between security and performance is essential.

Summarizing the different levels of database encryption

Here is a comparison chart of the different levels of encryption available in various relational database management systems:

Encryption LevelOracleMySQLMicrosoft SQL ServerPostgreSQL
Cluster-LevelTransparent Data Encryption (TDE)InnoDB PluginTransparent Data Encryption (TDE)N/A
Database-LevelTransparent Data Encryption (TDE)Encryption at RestTransparent Data Encryption (TDE)N/A
Table-LevelTransparent Data Encryption (TDE)Encryption at RestTransparent Data Encryption (TDE)N/A
Column-LevelTransparent Data Encryption (TDE)Encryption at RestTransparent Data Encryption (TDE)pgcrypto

 

Encryption LevelAmazon RDS (Oracle)Amazon RDS (MySQL)Azure SQL DatabaseGoogle Cloud SQL (MySQL)
Cluster-LevelTransparent Data Encryption (TDE)InnoDB PluginTransparent Data Encryption (TDE)N/A
Database-LevelTransparent Data Encryption (TDE)Encryption at RestTransparent Data Encryption (TDE)Full Disk Encryption, Transparent Data Encryption (TDE), File-level Encryption
Table-LevelTransparent Data Encryption (TDE)Encryption at RestTransparent Data Encryption (TDE)Transparent Data Encryption (TDE)
Column-LevelTransparent Data Encryption (TDE)Encryption at RestTransparent Data Encryption (TDE)Transparent Data Encryption (TDE)

 

Key management

Key management is vital to data at rest encryption in a relational database management system. This process involves creating, distributing, and managing keys to encrypt and decrypt data.

Several key management strategies can be used in an RDBMS, including:

  • Master Key Management: In this approach, a single master key is used to encrypt and decrypt all data in the RDBMS. This key is usually stored in a secure location, such as a hardware security module (HSM).
  • Column-Level Key Management: In this approach, each column of data is encrypted using a separate key. This allows for more granular control over data access and improves performance because only the necessary columns are decrypted when querying data.
  • Table-Level Key Management: Similar to column-level key management, this approach uses a separate key for each table in the RDBMS. This allows for even greater data access control and improved performance.

Regardless of which key management strategy is used, it is essential to have a robust system in place to ensure the security of encrypted data. This includes securely storing keys and quickly and easily rotating keys if there is a breach.

In addition to key management, it is also essential to consider the overall security of the RDBMS. This includes using secure protocols for communication, secure authentication methods, and implementing robust access controls to prevent unauthorized access to data.

Overall, key management is critical to data-at-rest encryption in an RDBMS. Organizations can protect their sensitive data from unauthorized access by implementing a strong key management system and taking steps to secure the RDBMS.

Transparent data encryption in PostgreSQL

The scope of TDE in PostgreSQL is limited to only column based. It does not encrypt other aspects of the database, such as table-level and database-level encryption; users may need to implement additional security measures to protect these database components.

 Learn more: Why PostgreSQL Needs Transparent Database Encryption (TDE)

PostgreSQL column-level encryption

We have discussed that PostgreSQL only has column-level encryption, which can be utilized by an extension called pgcrypto. This is the bare minimum implementation of encryption. It can only apply columns of the table, not on log files, whole rows, and databases.

The pgcrypto module in PostgreSQL is a powerful tool for securely storing and managing encrypted data within your database. With pgcrypto, you can easily encrypt data using a variety of algorithms and keys and then decrypt the data when needed. One of the key features of pgcrypto is its support for multiple encryption algorithms, including AES, Blowfish, and 3DES. This allows you to choose the best algorithm for your security needs and requirements.

To use pgcrypto, you will first need to install the extension in your PostgreSQL database. This can be done using the CREATE EXTENSION command:

Once the extension is installed, you can use the various functions of pgcrypto to encrypt and decrypt data. For example, you can use the pgp_sym_encrypt function to encrypt data using a symmetric key:

This will return the encrypted data as a bytea data type. The pgp_sym_encrypt function takes three arguments: the data to be encrypted, the symmetric key to be used for the encryption, and an initialization vector (IV) to be used for the encryption. The IV is a random value used to ensure that the same data encrypted with the same key will result in different encrypted outputs.

To decrypt the data, you can use the pgp_sym_decrypt function:

This will return the decrypted data as a text data type. The pgp_sym_decrypt function takes the same three arguments as the pgp_sym_encrypt function: the encrypted data, the symmetric key used to encrypt the data, and the IV used for the encryption.

In addition to symmetric key encryption, pgcrypto supports public-key encryption using the pgp_pub_encrypt and pgp_pub_decrypt functions. Public-key encryption is a type of encryption that uses a pair of keys: a public key and a private key. The public key encrypts the data, and the private key decrypts the data.

To use public-key encryption with pgcrypto, you will need to generate a pair of keys using the pgp_gen_key function:

This will generate a pair of keys and return them as a record. The pgp_gen_key function takes six arguments: the name of the key, the type of key to generate (in this case, “rsa”), the key size (in bits), optional passphrase and expiration values, and the user’s email address.

Once you have a pair of keys, you can use the pgp_pub_encrypt

Here is a complete example of encrypting and decrypting credit card data.

Now first, create a sample table with the serial number, credit card number, and when we created that card information. Here you can see only a credit card number is essential to hide from unauthorized users. Therefore we will only encrypt that column.

Now create a function generate_iv; the purpose of this function is to generate a random initialization vector (IV) that can be used for encryption. An IV is a random value that is used to ensure that the same data encrypted with the same key will result in different encrypted outputs. The generate_iv function can be called whenever an IV is needed for encryption.

The next step is to create encrypt_data. This function takes two input parameters: data of type bytea and key of type text. It returns a bytea data type. Inside the function, it first generates a random initialization vector (IV) using the generate_iv function. This is done using a WITH clause and a subquery. Next, the function uses the pgp_sym_encrypt function to encrypt the data parameter using the key and iv as input. The encrypted data is returned by the function using the SELECT statement. The purpose of this function is to provide a convenient way to encrypt data using a symmetric key and a random IV. You can call the encrypt_data function and pass in the data you want to encrypt and the key for encryption. The function will generate the random IV and perform the encryption for you.

Insert a row in the table.

The pgcrypto extension in PostgreSQL provides several cryptographic functions that perform various types of encryption and decryption. Some of the encryption algorithms that are supported include:

  • AES (Advanced Encryption Standard)
  • Blowfish
  • DES (Data Encryption Standard)
  • MD5 (Message Digest Algorithm 5)
  • SHA-1 (Secure Hash Algorithm 1)
  • SHA-2 (Secure Hash Algorithm 2)
  • SHA-3 (Secure Hash Algorithm 3)
  • HMAC (Keyed-Hash Message Authentication Code)

PostgreSQL transparent data encryption future

Currently, there is no Transparent Data Encryption available in vanilla PostgreSQL. There have been many discussions in the PostgreSQL community to implement that, but none was committed. But there are some PostgreSQL forks owned by companies that provide these. Here is an example architecture for the Transparent data encryption for PostgreSQL.

TDE

 

Use cases for Transparent Data Encryption

Transparent Data Encryption (TDE) is crucial in protecting data across a wide range of contexts, providing an additional layer of security for sensitive information. Its applications are diverse, with each area having its own set of data protection and privacy requirements. Below, we look at various application scenarios where TDE is useful.

Protecting sensitive data in financial services 

In financial services, safeguarding critical customer data and transaction information is essential. TDE plays a key role by encrypting data at rest—including account details, transaction records, and personal identification data—thus reducing the threat of data breaches and financial deceit. Serving as a fundamental element of data security tactics, this encryption method offers a reliable base for the secure handling and storage of substantial volumes of sensitive data.

Healthcare data security 

The healthcare industry handles very sensitive patient information, so data security is a top priority. TDE aids healthcare institutions with encrypting patient records, which include medical histories, treatment plans, and personal identifiers, to ensure that unauthorized individuals cannot access them. This not only preserves patient privacy but also helps healthcare providers comply with data protection standards like HIPAA.

Cloud data storage 

TDE provides a seamless solution for encrypting data before it is stored in the cloud, protecting against unauthorized access and ensuring that sensitive information remains private, regardless of the cloud provider’s underlying security measures.

Regulatory compliance across industries 

Many industries are governed by regulatory standards that mandate the encryption of sensitive data. TDE assists organizations in meeting these requirements, providing a method to ensure data at rest is encrypted and in compliance with laws such as GDPR, PCI DSS, and others so businesses can avoid fines and penalties associated with non-compliance.

What are the potential challenges of Transparent Data Encryption?

The main potential challenges of Transparent Data Encryption include:

Performance overhead

Transparent Data Encryption can introduce a performance overhead due to the additional processing required for encrypting and decrypting data.

Key management complexity

Managing encryption keys with TDE adds complexity to database administration, requiring key storage, rotation, and access control processes to ensure data security.

Cost implications

TDE may lead to higher costs related to licensing, especially for commercial database systems, and the need for additional hardware resources to offset performance impacts.

Backup and recovery considerations

Implementing TDE necessitates careful preparation for backup and recovery operations, as backups of encrypted data must be supported by effective key management to ensure successful data restoration and decryption.

Limited scope of protection 

While TDE secures data at rest, it doesn’t protect against every security threat, such as those targeting data in transit or use.

Compliance and regulatory challenges 

Meeting the demands of compliance and regulatory standards with TDE implementations can be difficult and requires continuous oversight and modifications to adhere to changing regulations.

Best practices for Transparent Data Encryption

Implementing Transparent Data Encryption effectively requires adherence to several best practices to ensure data security while maintaining system performance and compliance. Here, we look at key strategies to optimize TDE deployment:

Key management 

Effective key management is essential for TDE, focusing on secure storage, routine rotation, and controlled access to encryption keys. Implementing a secure storage solution and a regular rotation schedule is critical to prevent unauthorized access and bolster security.

Performance tuning 

TDE may affect database performance because of the additional encryption and decryption processing. You can minimize this by tuning database settings, analyzing workload patterns, and considering hardware upgrades to maintain optimal performance.

Access control integration 

Ensure that only authorized users have access to encryption keys and the ability to decrypt data, aligning TDE policies with your organization’s access control and data security strategies.

Regular auditing and compliance checks 

Conduct regular audits and compliance checks to ensure that TDE implementation is consistent with organizational policies and regulatory requirements. 

Encryption strategy alignment 

Align your TDE strategy with your organization’s general data encryption and security standards. This alignment should take into account the types of data that require encryption, regulatory compliance requirements, and how TDE fits into the overall security framework, resulting in a unified and effective encryption approach.

Disaster recovery planning 

Incorporate TDE into your disaster recovery planning to ensure that encrypted data can be effectively restored in the event of a system failure or data loss. Proper key management plays a vital role in disaster recovery efforts, as keys must be available and secure to decrypt data successfully.

How can Percona help with Transparent Data Encryption?

Overall, TDE is a powerful tool for protecting sensitive data in a database. By encrypting data at rest and in motion, TDE helps to ensure that the data is secure throughout its lifecycle. Using key management techniques, such as an EMK or an external KMS, users can further secure their encrypted data and maintain control over it.

Choosing Percona for your database security needs ensures that your data is managed by experts committed to delivering unparalleled security and operational efficiency. Our team provides continuous, 24/7 support to ensure regulatory compliance, enhance system performance, and minimize any potential downtime. Dedicated to proactive problem-solving and security enhancements, we strive to provide your organization with a secure, reliable database environment, giving you peace of mind and a foundation for success.

Take control of PostgreSQL security, explore our “PostgreSQL Security Missteps and Tips” eBook for an in-depth analysis of essential security practices to safeguard your PostgreSQL databases. It tells you how to avoid common pitfalls and enhance security measures. Strengthen your database’s defense by downloading this resource and leveraging its expert insights for a more secure and robust PostgreSQL environment.

We also have an on-demand webinar discussing enterprise-grade PostgreSQL built on open-source tools. Access both the eBook and the webinar with the links below!

 

Download eBook   Watch Webinar

 

FAQs

1. What is Transparent Data Encryption (TDE)?

Transparent Data Encryption (TDE) is a security feature that encrypts data at the storage level, ensuring that sensitive data is encrypted within the database files on disk without requiring changes to the application.

2. How does TDE protect data at rest?

TDE protects data at rest by encrypting the database’s data files and log files on the disk, meaning that if someone were to gain physical access to the storage, they would not be able to read the data without the encryption keys.

3. Can TDE encrypt existing data in a database?

Yes, TDE is able to encrypt existing data in a database. When enabled, it encrypts the existing data in the background without interrupting the database service.

4. Does TDE affect database performance?

Implementing TDE may influence database performance due to the extra CPU effort needed for encryption and decryption processes. However, this effect is typically slight and can be effectively minimized with appropriate hardware selection and system configuration.

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