Front-end servers intercept raw fiber-optic traffic, reassembling fragmented TCP packets on the fly.

The code revealed that XKEYSCORE was programmed to catch specific data packets with incredible precision. The following rule, for instance, highlights a focus on Tor bridge distribution:

Our team has spent 72 hours auditing the source code obtained via a secure drop. The repository, timestamped from 2019, suggests these tools are still actively maintained. Here are the most shocking revelations.

XKEYSCORE’s power lies in its ability to extract intelligence from seemingly anonymous traffic. The system uses specific techniques to unmask users based on their online behavior. Tor and VPN Tracking

While the public has understood the concept of XKEYSCORE for over a decade, analyzing the architectural logic behind its source code reveals exactly how the platform transforms the chaotic firehose of global internet traffic into an indexed, searchable repository of private human communication. The Architecture of a Global Dragnet

Because XKEYSCORE parsers must read and decode complex, malformed, and deliberately corrupted packets to find exploits or hidden data, the system itself is vulnerable to exploitation. A maliciously crafted network packet sent over the open internet could theoretically trigger a buffer overflow or remote code execution vulnerability inside the XKEYSCORE interception node, compromising the surveillance system itself. Lack of Internal Cryptographic Auditing

XKEYSCORE operates at the edge of the NSA’s collection infrastructure. Instead of centralizing petabytes of raw internet traffic—which would overwhelm global communications networks—the system deploys specialized hardware to intercept points worldwide.

Every device leaves a distinct digital footprint when it interacts with the internet. XKeyscore tracks these variations with extreme precision:

This rule triggers when a user visits the official Tor Project website — the user is connecting from a Five Eyes nation (US, UK, Canada, Australia, New Zealand). According to the document, simply searching the web for the Linux Journal or privacy tools could cause the NSA to mark the IP address of the person doing the search.

The code reveals specific algorithmic techniques for identifying users (e.g., how the system detects specific VOIP protocols or fingerprints browsers). This allows for a granular understanding of how the NSA masks its presence. 2. Identifying Vulnerabilities

As packets pass through the intercept points, high-speed DPI cards reassemble TCP/UDP sessions in real time. The system parses application-layer protocols, including HTTP, SMTP, IMAP, POP3, and various VPN protocols. Deconstructing the Source Code Logic

Unlike systems that query archival data, XKeyscore analyzes data as it passes through .

To understand the scale, we must look at the database schema buried in the source. XKEYSCORE does not use SQL or standard NoSQL. It uses a binary columnar store called DB-XS . The source code includes a header file defining the "Master Index":