The Divine

A smart contract that allowed us to generate and secure pseudo-random numbers for the lowest cost. All processes and algorithms are transparent and open to everyone. The algorithm is thus safe and acceptable for a wide range of PRNG applications and situations where the cost to manipulate outweigh the transaction value.

Disclaimer

Do not use this algorithm in gambling and/or use it at your own risk. Do not use this algorithm in cryptography. We highly recommend it as an extra salt to improve your random result.

What is the idea behind it?

The idea

We get blockhash of 32nd older blocks from blockchain and combine with immortal by using xor operator then calculate its digest by using keccak256 hash function. The new immortal value will be assigned with the given digest from the above step.

    immortal <- blockchain state
    currentBlock <- blockchain state
    immortal <- keccak256(blockhash(currentBlock - 32) xor immortal)
    return immortal

We restrict the normal account to trigger this smart contract to prevent manipulation, the only way to trigger it is through a deployed smart contract. As long as there are many users of The Divine we could able to maintain an immortal chain of entropy.

Implementation

EVM assembly

60    PUSH1 0x20      ; [0x20]
3d    RETURNDATASIZE  ; [0x00, 0x20]
33    CALLER          ; [msg.sender, 0x00, 0x20]
32    ORIGIN          ; [tx.origin, msg.sender, 0x00, 0x20]
18    XOR             ; [tx.origin xor msg.sender, 0x00, 0x20]
60    PUSH1 0x0a      ; [jumpdest, tx.origin xor msg.sender, 0x00, 0x20]
57    JUMPI           ; [0x00, 0x20]
fd    REVERT          ; We do revert(0x00, 0x20), if tx.origin == msg.sender
5b    JUMPDEST        ; [0x00, 0x20]
81    DUP2            ; [0x20, 0x00, 0x20]
81    DUP2            ; [0x00, 0x20, 0x00, 0x20]
80    DUP1            ; [0x00, 0x00, 0x20, 0x00, 0x20]
54    SLOAD           ; [immortal, 0x00, 0x20, 0x00, 0x20]
82    DUP3            ; [0x20, immortal, 0x00, 0x20, 0x00, 0x20]
43    NUMBER          ; [block.number, 0x20, immortal, 0x00, 0x20, 0x00, 0x20]
03    SUB             ; [block.number - 0x20, immortal, 0x00, 0x20, 0x00, 0x20]
40    BLOCKHASH       ; [blockhash, immortal, 0x00, 0x20, 0x00, 0x20]
18    XOR             ; [blockhash xor immortal, 0x00, 0x20, 0x00, 0x20]
81    DUP2            ; [0x00, blockhash xor immortal, 0x00, 0x20, 0x00, 0x20]
52    MSTORE          ; [0x00, 0x20, 0x00, 0x20]
20    SHA3            ; [sha3(blockhash xor immortal), 0x00, 0x20]
81    DUP2            ; [0x00, sha3(blockhash xor immortal), 0x00, 0x20]
55    SSTORE          ; [0x00, 0x20]
f3    RETURN          ; []

Opcode:

0x60203d333218600a57fd5b8181805482430340188152208155f3

Deployment

Compile opcode

I wrote my assembler, you would try and get the same result:

$ node ./assembler/index.js
60    PUSH1 0x20
3d    RETURNDATASIZE
33    CALLER
32    ORIGIN
18    XOR
60    PUSH1 0x0a
57    JUMPI
fd    REVERT
5b    JUMPDEST
81    DUP2
81    DUP2
80    DUP1
54    SLOAD
82    DUP3
43    NUMBER
03    SUB
40    BLOCKHASH
18    XOR
81    DUP2
52    MSTORE
20    SHA3
81    DUP2
55    SSTORE
f3    RETURN

Output:          60203d333218600a57fd5b8181805482430340188152208155f3
Tx deploy data:  601a803d90600a8239f360203d333218600a57fd5b8181805482430340188152208155f3

Ethereum

The Divine was deployed in 0xb2e8610f3c8710c07965f1de7d72345011c8be3b4bdfa9823168017d180754ac at 0xb7E5468671dEDaf316B73494B9bE73a5aDbA1cdf

Fantom

The Divine was deployed in 0xe75b31f4bb2a837fe951597458cdc99480b973e5c32500f2eb7b63dc9f5a8fce at 0x4B9fd51e5D6E6935635940532d1C5F0B11235630

Binance Smart Chain

The Divine was deployed in 0x73ca699adfe8ae9204dbe299ae2c1492f09999e51950df5278bf3a9f0164cb1a at 0xF52a83a3B7d918B66BD9ae117519ddC436A82031

Polygon

The Divine was deployed in 0x7475de6549e9d4bd717f18972dcd1c57fea36d94cb5607a66ca92f33515f863a at 0x8F2F05d2A036C9AE279B333CAE12c9eC79f6C553

Rinkeby

The Divine was deployed in 0x28881447f735195e05546946c9cd404f0a194e94232a3a432f090ac5777adb19 at 0x69807cbCa149B58772F0732DcB820C268c5c6093

Data is:

0x601a803d90600a8239f360203d333218600a57fd5b8181805482430340188152208155f3

What is `601a803d90600a8239f3` ?

This is code that was optimized to deploy a smart contract.

0000    60  PUSH1 0x1a      ; [divineCode.length]
0002    80  DUP1            ; [divineCode.length, divineCode.length]
0003    3D  RETURNDATASIZE  ; [0x00, divineCode.length, divineCode.length]
0004    90  SWAP1           ; [divineCode.length, 0x00, divineCode.length]
0005    60  PUSH1 0x0a      ; [0x0a, divineCode.length, 0x00, divineCode.length]
0007    82  DUP3            ; [0x00, 0x0a, divineCode.length, 0x00, divineCode.length]
0008    39  CODECOPY        ; [0x00, divineCode.length]
0009    F3  *RETURN         ; []

It will return a pointer to memory[divineCode.offset:divineCode.length]

How to use TheDivine?

Usage:

Ethereum Mainnet:

0xb7E5468671dEDaf316B73494B9bE73a5aDbA1cdf

Fantom:

0x4B9fd51e5D6E6935635940532d1C5F0B11235630

Binance Smart Chain:

0xF52a83a3B7d918B66BD9ae117519ddC436A82031

Polygon:

0x8F2F05d2A036C9AE279B333CAE12c9eC79f6C553

// SPDX-License-Identifier: MIT
pragma solidity >=0.7.5 <0.9.0;

interface TheDivine {
    function rand() external returns(uint256);
}

contract TestTheDivine{
    event Log(uint256 indexed _value);

    function testRand() public {
        emit Log(TheDivine(0xb7E5468671dEDaf316B73494B9bE73a5aDbA1cdf).rand());
    }
}

Gas cost is around 5190 Gas each call.

Testing

Testing transaction on Binance Smart Chain: 0xf3b4e1a032904c61c617ec365e9c288d2e1fb8095f1298708974e14d4def2b1b

Reference

A Pseudorandom Number Generator with KECCAK Hash Function

License

This software distributed under MIT License

kethcode/thedivine