VDF

warning

These docs are for V1 of Eat The Pie, which is now deprecated. For the latest documentation for V2 on World Chain, please visit docs.eatthepie.xyz.

Github Link: https://github.com/eatthepie/contracts/blob/main/src/VDFPietrzak.sol

The VDF contract implements the VDF Pietzrak Library.

Contract Structure

Dependencies

• PietrzakLibrary: Library implementing the core VDF calculations
• BigNumbers: Library for handling large number operations

Constants

Below are the parameters used for our implementation in the lottery:

Parameter	Value	Description
N	c7970ce...cc7e5	The RSA-2048 challenge number used as the modulus. This massive 2048-bit number has no known prime factors, making it ideal for cryptographic security. (Learn more about RSA-2048)
nBitLength	2048	The bit length of our RSA modulus
delta	10	Number of iterations to skip during verification, optimizing the trade-off between prover and verifier computation time
T	67108864 (2²⁶)	Total number of sequential iterations required for the VDF computation. This parameter is set to create a ~5 hour delay on modern hardware

Core Functionality

VDF Verification

function verifyPietrzak(
    BigNumber[] memory v,
    BigNumber memory x,
    BigNumber memory y
) external view returns (bool)

Parameters

• v: Array of intermediate values in the VDF computation
• x: Initial input to the VDF (RANDAO value)
• y: Purported output of the VDF

Returns

• bool: True if the proof is valid, false otherwise

Process

1. Creates BigNumber representation of RSA modulus
2. Delegates verification to PietrzakLibrary
3. Performs efficient proof verification

Technical Details

VDF Properties

1. Fast Verification

   • Uses skip parameter (delta) for efficient verification
   • Verification time logarithmic in total iterations
   • Much faster than computation time

2. Security Guarantees

   • Based on time-lock puzzles
   • Uses trusted RSA modulus
   • Provably secure under standard assumptions