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Julie Taylor

The Precise Power of Selective Encryption for Unstructured Data Protection

Encryption is a proven method for data protection. It’s based on math, and math works. However, establishing strong policies is equally important — do you need full-disk encryption or file-level encryption? You might want certain files accessible only to specific individuals. Or, you may need a more granular approach where files remain accessible, but sensitive parts are hidden and only available on a selective, need-to-know basis. Making information available to the right people at the right time is a business priority. Proactive data protection is also a business imperative. Finding the right balance between them is key. 





The Business Case for Selective Encryption

Selective encryption is a method where only specific, sensitive parts of a document are encrypted, leaving the rest of the document in its original form. For instance, some departments of the DoD need to enable data sharing in standard document formats like PDFs, Microsoft Office Word documents, and Excel sheets. However, some portions are not releasable to certain people, such as foreigners. 


Typically, someone manually redacts that information and creates multiple copies, each suitable for different user groups. But that process is flawed. Selective encryption can elegantly solve this issue across regulated industries like finance, pharmaceuticals, healthcare and life sciences as well as in defense and government. In addition, encrypting entire files or documents can render them unusable for processing, which can be problematic, particularly with the increasing reliance on genAI and LLM-based applications that require access to these documents for fine-tuning and effective use. 


While advanced cryptography offers solutions like homomorphic and polymorphic encryption algorithms, which enable computations on encrypted data, they are often resource-intensive and predominantly suited for structured data. They are not suited for unstructured data in PDFs, images, Microsoft Office files, and emails.


Selective encryption, on the other hand, allows for encrypting only sensitive portions or data fields within any file type, leaving the rest accessible for existing workflows and applications. This technology originated from projects at SRI International, notably the DARPA-funded Brandeis program. The goal is to automate and simplify the traditionally manual and error-prone process of redacting sensitive information from documents before sharing them with partners or collaborators.



Redaction vs Tokenization vs Selective Encryption

Traditional methods for selective protection include tokenization, redaction, and selective encryption, each offering varying levels of security and flexibility.


  • Redaction: Permanently removes sensitive content from a document. While effective, it’s a one-way function as original information cannot be recovered from a redacted file. In order to allow dynamic access to sensitive information, organizations must maintain multiple versions of the file with varying levels of redaction.  

  • Tokenization: Replaces sensitive content with tokens that are indexed in a separate database. While reversible, it introduces dependency on the database for retrieving the original content from tokens.


  • Selective encryption: Context-aware, dynamic redaction that allows access to encrypted content if the user has appropriate credentials and authorization. With this method, the content still lives in the same file, maintaining the file's original format and compatibility with existing viewers, editors, and workflows.


Benefits of Selective Encryption


  • Least Privileged Access: Ensures that only authorized individuals with the necessary privileges can access sensitive information within a document.

  • Maximizing Utility: Encrypts only sensitive portions of documents, allowing the remainder to be readily accessible for enterprise activities such as searching, indexing, AI model training, and collaboration.

  • Minimal User Impact: Provides robust security for sensitive data without significantly affecting the user experience within the organization.

  • De-risk breaches: Ensure that even if attackers gain access to your system and download documents, they cannot access sensitive information.


Best Practices for Selective Encryption

The effectiveness of selective encryption relies on adhering to specific best practices. These include maintaining: 


  • Cryptographic Standards: Use encryption algorithms and key sizes that conform to standards set by bodies like NIST and ISO; for instance, AES-256 for symmetric encryption and RSA-4096 for asymmetric encryption. 


  • Robust Key Management: Implement effective key management practices such as NIST-certified random number generation for key creation, secure storage in hardware security modules (HSMs), and automated rotation to name a few.


  • Crypto-Agility: Ensure encryption mechanisms can adapt to future threats and technologies, including quantum computing. Future-proofing requires selecting tools and platforms capable of seamless transition to quantum-safe algorithms without requiring complete platform or infrastructure overhauls.


  • Frictionless User Experience: Simplify integration of encryption processes within existing workflows and tools to minimize user resistance and reduce the likelihood of security bypasses. 


These capabilities are essential for effective and robust selective encryption enforcement; however, manual implementation is complex. It’s always better to choose tools and platforms that have these capabilities built in rather than enforcing complex algorithms in-house.


Implement Selective Encryption with Confidencial


Confidencial is the pioneer in selective encryption, offering a comprehensive suite of tools and features that allow secure information sharing without compromising user-experience. Here’s what makes Confidencial the right choice for protecting your document workflows:


  • Utilizes vetted encryption algorithms (RSA-OAEP and AES-256-GCM) that conform to NIST standards.

  • Supports data-blind architecture, meaning your data never touches Confidencial’s servers.  

  • Addresses compliance requirements from regulations like GDPR in Europe and CCPA in the US.

  • Supports protection across on-premise and multi-cloud storage, regardless of the provider. 

  • Integrates AI to automatically identify and classify sensitive data in all files. 

  • Supports unstructured data and file formats, including PDFs, Images, Docs, and Sheets.

  • Maintains file format and integrates with existing workflows for a seamless user experience. 

  • Embeds encryption and access controls within files which maintains security throughout the content's lifecycle.

  • Integrates fine-grained cryptographic access controls based on custom policies.

  • Supports seamless upgrade to post-quantum encryption standards.

  • Enhances security and accountability through detailed access logs.


Read our whitepaper to learn about Confidencial’s robust selective encryption mechanism. Or, get in touch with one of our experts to experience firsthand how you can take advantage of selective protection to improve  

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