NFT Sale Proxy

A proxy to hide NFT metadata during the sale and prevent people from sniping specific NFTs.

Usage examples: examples

What is this?

A common practice for gacha style NFT drops with off-chain metadata is to:

1. Have a url to get the token metadata similar to https://example.com/{id} or ipfs://{CID}/{id}
2. Have incremental ids for each NFT, so in a 10k collection you have a token with id 1, another with id 2 and this continues up to id 10000.

In this scenario, anyone can find out the traits of a token before it is minted, bypassing the gacha mechanic. A more advanced minter can even fetch the metadata for all tokens, find the most rares and snipe them, giving them an unfair advantage. You can read more about this in this blog post.

This repo contains a simple solution for this problem: A proxy that returns a fake nft metadata (configured by you) or the real nft metadata (fetches it from somewhere else and forwards the response) depending on your configuration and what the user requested.

For example, if the token metadata is in an IPFS folder, the proxy would fetch the metadata from that IPFS folder and return the result to the user if the token is revealed.

Revealed Token	Non Revealed Token

The behaviour is configured by using environment variables, for the example in the images above, the configuration would looks similar to this:

BASE_URL=https://ipfs.io/ipfs/<METADATA-CID-FOLDER>/
INCOGNITO_IMAGE_URL=<URL_TO_FAKE_LINK>
INCOGNITO_NAME="My Collection #{id}" # Will render as 'My Collection #123' for example
INCOGNITO_DESCRIPTION="A nice collection"
INCOGNITO_EXTERNAL_LINK="https://mycollection.com"
NUMBER_OF_TOKENS=8888
REVEAL_UP_TO=500 # Show real data from ids 0~500 (including 500) and show fake metadata from ids 501+
OTHER_REVEALS: 1100-1200,1600-1700 # Also show real data from ids 1100~1200, 1600~1700

Getting Started

AWS Lambda

To create the proxy using AWS Lambda is very simple, you just need a go file with the code below:

package main

import (
  proxy "github.com/alephao/nft-sale-proxy/pkg/aws-lambda"
  "github.com/aws/aws-lambda-go/lambda"
)

func main() {
  lambda.Start(proxy.HandleRequest)
}

Then you need to make the environment variables listed below available during runtime.

You can see a complete example here

Configuration

The proxy is configured using environment variables:

Name	Description
BASE_URL	The baseURL that contains the actual token metadata
INCOGNITO_IMAGE_URL	The URL to the image that will show for non-revealed tokens
INCOGNITO_NAME	The name attribute that will show for non-revealed tokens. You can use the placeholder {id} and it will be replaced by the token id.
INCOGNITO_DESCRIPTION	The description attribute that will show for non-revealed tokens
INCOGNITO_EXTERNAL_LINK	The external_link attribute that will show for non-revealed tokens
NUMBER_OF_TOKENS	The maximum amount of tokens. The proxy will return 404 for incoming requests with a number highe than this value
REVEAL_UP_TO	The highest token id that will be revealed. Start with -1, to reveal none. To reveal the first 1000, change to 999. Etc.
OTHER_REVEALS	Other ranges of token ids to be revealed. Should be a string in the format the following format: <FROM>-<TO>,<FROM2>-<TO2> e.g.: 1100-1200,1600-1700 will reveal token ids between 1100-1200 and 1600-1700 inclusive.
ERC1155	Set this to true if the token is an ERC1155. This will use 32 bytes hex values padded with 0s as the id.