Opoch - a STARK/FRI proof-of-computation for sequential SHA-256 hash …

[ravish-oo]

This PR adds OPOCHto the zk-benchmarks suite. OPOCH is a STARK-based proof system specialized for SHA-256 hash chain computation, using FRI (Fast Reed-Solomon IOP) over the Goldilocks field.

What's Added

• opoch/ - New benchmark folder with benchy-based benchmarks
• Updated .github/workflows/benchmarks.yml to include OPOCH in CI

Benchmarks

SHA256 Hash Chain Proving - Proves N iterations of h_{i+1} = SHA256(h_i)

• N=64, N=256, N=1024, N=4096

SHA256 Chain Verify - Verification-only benchmark (OPOCH's key strength)

• N=64, N=1024, N=4096

Results (Apple M-series, local)

Proving

N	Time	Proof Size	Compressed
64	6.9s	321 bytes	186 bytes
256	27.6s	321 bytes	186 bytes
1024	110s	321 bytes	188 bytes
4096	440s	321 bytes	188 bytes

Verification

N	Time	Proof Size
64	7.8 µs	321 bytes
1024	21 µs	321 bytes
4096	19 µs	321 bytes

Key Differentiators

• Constant proof size: 321 bytes regardless of N (vs 40KB-200KB for other zkVMs)
• Compressed size: 186 bytes with zstd
• Sub-millisecond verification: ~8-20 µs (vs 2-15 ms for other frameworks)
• Verification scales O(1): Time nearly constant regardless of computation size
• No Groth16 wrapper needed: Native STARK proofs are already small

Technical Details

• Proof System: STARK with FRI-based polynomial commitment
• Field: Goldilocks (64-bit prime field)
• Security: 128-bit (68 FRI queries, 8x blowup factor)
• Architecture: Segment proofs → Level-1 aggregation → Level-2 aggregation

Checklist

• Follows existing benchmark structure (Cargo.toml, benches/bench.rs, src/lib.rs)
• Uses benchy crate with standard metrics (proof_size_bytes, compressed_proof_size_bytes)
• Added to CI workflow
• Tested locally with cargo bench

Repo: https://github.com/chetannothingness/opoch-hash

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[ravish-oo]

@timmyjose - cna u pls check this PR?