The Critical Verification: Confirming Golden Test Data for the cuzk SNARK Proving Daemon

In the course of designing a new pipelined SNARK proving daemon called cuzk, an assistant found itself deep in an investigative rabbit hole, systematically probing every layer of an existing Filecoin proof generation pipeline. The message at index 86 represents a pivotal moment of empirical verification—a single, focused Python command that confirmed the golden test data was real, usable, and precisely what the architecture design required. This article examines that message in detail, unpacking the reasoning, context, assumptions, and knowledge created by this concise but consequential investigative step.

The Message in Full

The message contains a single bash command execution:

python3 -c "
import json
with open('/data/32gbench/c1.json', 'r') as f:
    data = json.load(f)
print('SectorNum:', data.get('SectorNum'))
print('SectorSize:', data.get('SectorSize'))
p1 = data.get('Phase1Out', '')
print('Phase1Out length:', len(p1))
print('Phase1Out first 200 chars:', p1[:200])
"

The output reveals:

SectorNum: 1
SectorSize: 34359738368
Phase1Out length: 51510672
Phase1Out first 200 chars: eyJyZWdpc3RlcmVkX3Byb29mIjoiU3RhY2tlZERyZzMyR2lCVjFfMSIsInZhbmlsbGFfcHJvb2ZzIjp7IlN0YWNrZWREcmczMkdpQlYxIjpbW3siY29tbV9kX3Byb29mcyI6eyJkYXRhIjp7IlNpbmdsZSI6eyJyb290IjpbNywxMjYsOTUsMjIyLDUzLDE5NywxMCwx

At first glance, this looks like a routine data inspection. But in the context of the broader investigation—designing a daemon that must orchestrate GPU memory, schedule proof jobs, and manage SRS parameters across multiple proof types—this verification was essential groundwork.

Why This Message Was Written: The Investigative Context

The message did not emerge from nowhere. It was the culmination of a sustained exploration spanning multiple prior messages. The user had requested ([msg 78]) that the assistant write a comprehensive cuzk-project.md document, with specific notes about building a testing utility that could exercise the proving pipeline using existing golden data. The user pointed to /data/32gbench/ as containing "a bunch of golden files including a snap sector" and suggested using lotus-bench simple commands to generate vanilla proofs.

The assistant then embarked on a systematic survey of the environment. It listed the contents of /data/32gbench/ ([msg 79]), discovering a rich collection of test artifacts: c1.json, c1-8p.json, c1-single.json, commdr.txt, cache directories with multi-gigabyte layer files, and update cache directories. It explored the lotus-bench simple command tree (<msgs id=81-82>), discovering subcommands for commit2, window-post, provereplicaupdate1, provereplicaupdate2, winning-post, and commit1. It inspected the parameter files in /var/tmp/filecoin-proof-parameters/ (<msg id=83-84>), finding that only small-sector (8-0-0) parameters were downloaded, not the full 32 GiB (8-8-0) parameters. It decoded the pc1out.txt file ([msg 85]) to find it was a StackedDrg32GiBV1_1 proof—confirming the 32 GiB sector size.

But a critical ambiguity remained. When the assistant first inspected c1.json ([msg 85]), it found the top-level keys were [&#39;SectorNum&#39;, &#39;Phase1Out&#39;, &#39;SectorSize&#39;] and that registered_proof: N/A. This was puzzling. The c1.json file is supposed to be the output of Phase 1 (C1) of the PoRep pipeline, which gets fed into Phase 2 (C2) for Groth16 proof generation. If the top level didn't contain the proof type, where was it? The answer lay inside the Phase1Out field—a large base64-encoded blob whose contents were unknown.

This is precisely what message 86 resolves. The assistant needed to know:

  1. What is the actual sector size? The SectorSize field existed but could have been a default or placeholder. Was it really 32 GiB (34359738368 bytes)?
  2. What proof type does this C1 output represent? The proof type determines the circuit size, the SRS parameters needed, and the memory requirements for C2. Without this, the cuzk architecture could not be properly designed.
  3. How large is the Phase1Out data? The C2 pipeline needs to load and process this data. Its size affects memory budgeting, transfer costs, and scheduling decisions.
  4. Is the Phase1Out well-formed? Does it decode to a valid structure that the C2 pipeline can consume?

How Decisions Were Made

The assistant's choice of tooling reveals a deliberate decision-making process. Rather than using shell utilities like base64 -d piped through jq, or writing a standalone Python script, the assistant crafted a single inline Python command that:

Assumptions Embedded in the Investigation

This message rests on several assumptions, most of which are validated by the output:

The file is valid JSON. The assistant assumes c1.json can be parsed by json.load(). This is confirmed by the successful execution.

The Phase1Out field is base64-encoded JSON. The assistant does not explicitly decode it, but the first 200 characters are clearly base64 (the character set [A-Za-z0-9+/=]). The assistant implicitly trusts that this is the standard Filecoin encoding format—a reasonable assumption given the context of the lotus-bench pipeline.

The sector size field is accurate. The assistant takes SectorSize: 34359738368 at face value. This is 32 GiB (32 × 1024^3 = 34359738368), which matches the StackedDrg32GiBV1_1 proof type found in pc1out.txt earlier ([msg 85]).

The data represents a real proof. The assistant assumes this is genuine golden test data, not synthetic or corrupted data. The consistency between the sector size, proof type, and Phase1Out structure validates this assumption.

The Phase1Out is complete and uncorrupted. The length (51510672 bytes ≈ 49 MiB) is plausible for a 32 GiB PoRep C1 output. The base64 prefix decodes cleanly to recognizable JSON.

Input Knowledge Required

To fully understand this message, one needs knowledge spanning several domains:

Filecoin PoRep Pipeline Architecture. The distinction between C1 (Phase 1) and C2 (Phase 2) is fundamental. C1 produces the Phase1Out data—a collection of vanilla proofs and commitments—which C2 then wraps into a Groth16 SNARK proof. The c1.json file is the bridge between these two phases.

Proof Type Naming Conventions. StackedDrg32GiBV1_1 identifies a specific proof variant: Stacked DRG (Depth-Robust Graph) for 32 GiB sectors, version 1_1. This determines the circuit parameters, SRS size, and memory footprint for C2.

Base64 Encoding in Filecoin. The Filecoin proof system frequently encodes JSON structures as base64 strings within larger JSON documents. This is a serialization pattern used throughout the lotus-bench and supraseal toolchains.

Memory and Resource Sizing. Knowing that 32 GiB sectors require the most memory-intensive C2 computation (~200 GiB peak, as established in earlier segments) is essential context. The Phase1Out size of ~49 MiB is modest compared to the SRS parameters (multiple gigabytes) and intermediate computation buffers.

The Broader cuzk Design Goal. This investigation feeds directly into the architecture of a daemon that must preload SRS parameters, schedule proof jobs across GPUs, and manage memory budgets. Confirming the test data is valid and representative is a prerequisite for designing the testing utility (cuzk-bench) that will validate the daemon's correctness.

Output Knowledge Created

This message produces several concrete facts that directly inform the cuzk architecture:

Sector Size Confirmed: 32 GiB (34359738368 bytes). This is the largest and most demanding sector size in Filecoin. Any daemon designed to handle this must also handle smaller sectors (512 MiB, etc.), but the 32 GiB case sets the upper bound on memory and compute requirements.

Proof Type Confirmed: StackedDrg32GiBV1_1. This determines which SRS parameters must be preloaded, which circuit is used, and which GPU kernels are invoked. The cuzk daemon's SRS manager must prioritize this parameter set.

Phase1Out Size: ~49 MiB (51510672 bytes). This is the data payload that must be transferred from storage to GPU memory for each C2 job. It is modest relative to the SRS parameters (1.1 GiB for the PoRep params) and the intermediate computation buffers (~200 GiB peak). This confirms that Phase1Out transfer is not a bottleneck.

Phase1Out Structure Verified. The base64 prefix decodes to {&#34;registered_proof&#34;:&#34;StackedDrg32GiBV1_1&#34;,&#34;vanilla_proofs&#34;:{..., confirming the expected schema. The C2 pipeline can parse this directly.

Test Data is Valid and Usable. The golden data in /data/32gbench/c1.json is genuine and can serve as input for cuzk-bench testing. This unblocks the testing utility design.

The Thinking Process Visible in the Message

While the message itself is concise, the reasoning behind it is visible through the sequence of prior investigations. The assistant had just discovered ([msg 85]) that the top-level c1.json had registered_proof: N/A. A less thorough investigator might have stopped there, assuming the data was incomplete or mislabeled. Instead, the assistant recognized that the proof type information was likely embedded within the Phase1Out field—a pattern common in Filecoin's serialization where inner payloads carry their own metadata.

The choice to print the first 200 characters of the base64 string, rather than decoding it fully, shows an understanding that the proof type would appear near the beginning of the decoded JSON. The base64 prefix eyJyZWdpc3RlcmVkX3Byb29mIjoiU3RhY2tlZERyZzMyR2lCVjFfMSI= decodes to {&#34;registered_proof&#34;:&#34;StackedDrg32GiBV1_1&#34;—exactly the information needed. This is efficient investigation: confirm the critical unknown with minimal computation.

The assistant also implicitly cross-references this result with the earlier finding from pc1out.txt ([msg 85]), which also contained registered_proof: StackedDrg32GiBV1_1. The consistency between these two independent data sources strengthens confidence in the test data's validity.

Conclusion

Message 86 is a small but critical node in a larger investigative network. It resolves an ambiguity about the golden test data, confirms the proof type and sector size, and provides concrete numbers that feed directly into the cuzk architecture design. The message exemplifies a pattern of systematic, assumption-validating investigation that characterizes the entire segment: probe the system, verify unknowns, confirm consistency, and build on solid empirical ground. Without this verification, the cuzk-project.md document would have been designed against uncertain assumptions—a risky foundation for a daemon that must manage gigabytes of GPU memory and orchestrate complex proof pipelines. With it, the architecture has a firm footing in reality.