> For the complete documentation index, see [llms.txt](https://docs.zulunetwork.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.zulunetwork.io/core-concepts/bitvm-zulu/bitvm-zkp-verifier.md).

# BitVM-ZKP-Verifier

The Zulu Network team has Open-Sourced the first ZKP Verify Code Implementation using Bitcoin Script! It involves mainstream algorithms such as Groth16/FFlonk, and we have submitted the code to the BitVM repository. 

Here are the links to our code:

* fflonk script

  * ​<https://github.com/BitVM/BitVM/pull/70>​

  ​
* Groth16's script
  * ​<https://github.com/BitVM/BitVM/pull/71>​
  * ​<https://github.com/zulu-network/bitvm-groth16-verifier>​

## **Importance of Snark Verifier Script**

Robin Linus, founder of BitVM, shared that the Snark Verifier script on Bitcoin is very important in BitVM2 ([https://bitvm.org/bitvm2](https://t.co/AnbVtpuxUW)).&#x20;

<figure><img src="/files/NUvZYDgRTMA1CdIptU4h" alt=""><figcaption></figcaption></figure>

He has also recently praised the efforts in development by the Zulu Network team: <https://x.com/robin_linus/status/1796206213077545079>

## Technical Implementation

{% hint style="success" %}
What is the size of the verifier for Groth16/Fflonk?&#x20;
{% endhint %}

> 1\. Fflonk Verifier:&#x20;
>
> Curve: BN254&#x20;
>
> Public input number: 2&#x20;
>
> Script size: 7456022084 bytes&#x20;
>
> Max stack items number: 905

> 2\. Groth16 Verifier:&#x20;
>
> Curve: BN254&#x20;
>
> Public input number: 1&#x20;
>
> Script size: 7034158970 bytes&#x20;
>
> Max stack items number: 1112 (Can be optimized)

Based on the current script size, we only need to split the entire ZKP script into fewer than 2,000 sub-scripts, which is remarkable. We are deeply grateful to all the contributors to the BitVM repository, including[@robin\_linus](https://x.com/robin_linus),[@weikengchen](https://x.com/weikengchen), and others.&#x20;

We also extend our thanks to Andrija Novakov from [@\_\_geometry\_\_](https://x.com/__geometry__)for their latest paper, "On Proving Pairings," [https://eprint.iacr.org/2024/640.pdf](https://t.co/RZKn2jlgti) which significantly reduces the overall script size.&#x20;

This achievement lays the foundation for constructing a decentralized bridge based on BitVM2. Zulu's next goal is to launch a trust-minimized Bitcoin bridge utilizing cross-chain technology and BitVM2.&#x20;

The snark verifier in the script on Bitcoin is a huge milestone for future Bitcoin developments, as BitVM creator[@robin\_linus](https://x.com/robin_linus) shared at ZK Proof 6 in Berlin.&#x20;

> Let's move Bitcoin forward!