Merge pull request #2142 from HackTricks-wiki/update_We_beat_Google_s_zero-knowledge_proof_of_quantum_c_20260417_131709

We beat Google’s zero-knowledge proof of quantum cryptanalys...

Author: carlospolop

src/blockchain/blockchain-and-crypto-currencies/README.md

@@ -210,14 +210,76 @@ erc-4337-smart-account-security-pitfalls.md
 ../smart-contract-security/mutation-testing-with-slither.md
 {{#endref}}
 
-## References
+## ZK Proof / zkVM Guest Integrity
 
-- [https://en.wikipedia.org/wiki/Proof_of_stake](https://en.wikipedia.org/wiki/Proof_of_stake)
-- [https://www.mycryptopedia.com/public-key-private-key-explained/](https://www.mycryptopedia.com/public-key-private-key-explained/)
-- [https://bitcoin.stackexchange.com/questions/3718/what-are-multi-signature-transactions](https://bitcoin.stackexchange.com/questions/3718/what-are-multi-signature-transactions)
-- [https://ethereum.org/en/developers/docs/transactions/](https://ethereum.org/en/developers/docs/transactions/)
-- [https://ethereum.org/en/developers/docs/gas/](https://ethereum.org/en/developers/docs/gas/)
-- [https://en.bitcoin.it/wiki/Privacy](https://en.bitcoin.it/wiki/Privacy#Forced_address_reuse)
+When a prover uses a **zkVM** or an application-specific proof circuit to attest a claim, the verifier is only learning that the **guest program executed as written**. If the guest contains **unsafe deserialization**, **undefined behavior**, or **missing semantic constraints**, a malicious prover may generate a proof that verifies while the **public metrics or claimed invariant are false**.
+
+### Unsafe deserialization inside proof guests
+
+- Treat private witness/circuit bytes as **untrusted attacker input** even if they are hidden by the proof.
+- Avoid deserializing them with unchecked helpers such as `rkyv::access_unchecked` unless the bytes were already validated out-of-band.
+- Enum discriminants, relative pointers, lengths, and indexes loaded from untrusted serialized data must be validated before they influence control flow or memory access.
+
+Practical audit pattern:
+
+```rust
+let private_circuit_bytes = sp1_zkvm::io::read_vec();
+let ops = unsafe {
+    rkyv::access_unchecked::<rkyv::Archived<Vec<Op>>>(&private_circuit_bytes)
+};
+```
+
+If a field such as `op.kind` is an enum and an attacker can inject an **out-of-range discriminant**, every downstream `match` on that value becomes suspicious.
+
+### Jump-table / UB counter bypass
+
+If Rust lowers a large `match` into a **jump table**, an invalid enum discriminant may produce **undefined control flow**. A dangerous pattern is:
+
+1. One `match` updates **security-critical counters/constraints**.
+2. A second `match` performs the **real instruction semantics**.
+3. An out-of-range discriminant indexes past the first jump table and lands in code associated with the second one.
+
+Result: the operation still executes, but the accounting path is skipped. In a zkVM this can forge proofs that report impossible metrics such as fewer gates, fewer expensive operations, or other falsified bounded resources.
+
+Review checklist:
+
+- Look for attacker-controlled enums deserialized from witness/private input.
+- Inspect repeated `match` statements over the same opcode/kind field.
+- Treat `unsafe` + unchecked deserialization + large opcode dispatch as a high-risk combination.
+- Reverse engineer the emitted binary when needed; jump-table layout can matter more than the source.
+
+### Missing semantic constraints in reversible/specialized interpreters
+
+Do not just validate memory safety; also validate the **semantic rules** that the proof is meant to enforce.
+
+For reversible/quantum-like instruction sets, ensure operands that must be distinct are actually constrained to be distinct. A Toffoli/CCX-like operation implemented as:
+
+```rust
+let v = cond & self.qubit(op.q_control1) & self.qubit(op.q_control2);
+*self.qubit_mut(op.q_target) ^= v;
+```
+
+becomes unsafe if the guest does not reject:
+
+```text
+op.q_control1 == op.q_control2 == op.q_target
+```
+
+In that case the transition collapses into:
+
+```text
+q = q ^ (q & q) = 0
+```
+
+This creates a **deterministic reset primitive**, breaking reversibility assumptions and enabling cheaper non-intended computations. In proof systems that attest resource usage, this can let attackers satisfy functional checks while bypassing the cost model the verifier believes is being enforced.
+
+### What to test in ZK systems
+
+- Fuzz all guest parsers with malformed witness/private-input encodings.
+- Assert enum range validation before opcode dispatch.
+- Add semantic checks for operand aliasing and other invalid instruction forms.
+- Compare reported/public counters against an independent reference implementation.
+- Remember that a valid proof can still prove the **wrong statement** if the guest program is buggy.
 
 ## DeFi/AMM Exploitation
 
@@ -233,6 +295,16 @@ For multi-asset weighted pools that cache virtual balances and can be poisoned w
 defi-amm-virtual-balance-cache-exploitation.md
 {{#endref}}
 
-{{#include ../../banners/hacktricks-training.md}}
+## References
 
+- [https://en.wikipedia.org/wiki/Proof_of_stake](https://en.wikipedia.org/wiki/Proof_of_stake)
+- [https://www.mycryptopedia.com/public-key-private-key-explained/](https://www.mycryptopedia.com/public-key-private-key-explained/)
+- [https://bitcoin.stackexchange.com/questions/3718/what-are-multi-signature-transactions](https://bitcoin.stackexchange.com/questions/3718/what-are-multi-signature-transactions)
+- [https://ethereum.org/en/developers/docs/transactions/](https://ethereum.org/en/developers/docs/transactions/)
+- [https://ethereum.org/en/developers/docs/gas/](https://ethereum.org/en/developers/docs/gas/)
+- [https://en.bitcoin.it/wiki/Privacy](https://en.bitcoin.it/wiki/Privacy#Forced_address_reuse)
+- [Trail of Bits - We beat Google's zero-knowledge proof of quantum cryptanalysis](https://blog.trailofbits.com/2026/04/17/we-beat-googles-zero-knowledge-proof-of-quantum-cryptanalysis/)
+- [Google patched paper version](https://arxiv.org/abs/2603.28846v2)
+- [Trail of Bits proof-of-concept repository](https://github.com/trailofbits/quantum-zk-proof-poc)
 
+{{#include ../../banners/hacktricks-training.md}}