are stored inside the sticker pack as a set of hyperlinks pointing to IPFS storage. These hyperlinks are publicly available and can be accessed by any user inside the status chat.
At the moment of writing, the current main Status app uses the [Infura](https://infura.io/) gateway. However, clients could choose a different gateway or to run own IPFS node.
derived from the hash of the file. This ensures that a file can't be overridden, and an end-user of the IPFS will receive the same file at a given address.
The IPFS gateway acts as an end-user of the IPFS and allows users of the gateway to access IPFS without connection to the P2P network.
Usage of a gateway introduces potential risk for the users of that gateway provider. In case of a compromise in the security of the provider, meta information such as IP address, User-Agent and other of its users can be leaked.
To send a sticker in chat, a user of Status should buy or install a sticker pack.
To be available for installation a Sticker Pack should be submitted to Sticker market by an author.
#### Submit a sticker
To submit a sticker pack, the author should upload all assets to IPFS. Then generate a payload including name, author, thumbnail, preview and a list of stickers in the [EDN format](https://github.com/edn-format/edn). Following this structure:
This payload is uploaded also to IPFS, and the IPFS address is used in the content field of the Sticker Market contract. See [Sticker Market spec](https://github.com/status-im/sticker-market/blob/651e88e5f38c690e57ecaad47f46b9641b8b1e27/docs/specification.md) for a detailed description of the contract.
#### Install a sticker pack
To install a sticker pack, we need to fetch all sticker packs which are available in Sticker Market. The following steps are needed to fetch all sticker packs:
ID's are represented as `uint256` and are incremental from `0` to total number of sticker packs in contract, which we received on previous step. To get a sticker pack we should call `getPackData(sticker-pack-id)`, the return type is `["bytes4[]" "address" "bool" "uint256" "uint256" "bytes"]` which represents the following fields: `[category owner mintable timestamp price contenthash]`. Price is the SNT value in wei set by sticker pack owner. The contenthash is the IPFS address described in the [submit description](#submit-a-sticker) above. Other fields specification could be found in [Sticker Market spec](https://github.com/status-im/sticker-market/blob/651e88e5f38c690e57ecaad47f46b9641b8b1e27/docs/specification.md)
The current Status app fetches owned sticker packs during the open of any sticker view (a screen which shows a sticker pack or the list of sticker packs).
To get owned packs, we should get all owned tokens for the current account address. To do that we should call `balanceOf(address)` where address is the address for current account. This method returns a `uint256` representing the count of available tokens. Using `tokenOfOwnerByIndex(address,uint256)` method, with the address of the user and ID in form of a `uint256` which is an incremented int from 0 to total number of tokens, we will get token id. To get sticker pack id from token we call`tokenPackId(uint256)` where `uint256` is the token id. This method will return an `uint256` which is the id of the owned sticker pack.
To buy a sticker pack we should call `approveAndCall(address,uint256,bytes)` where `address` is the address of buyer,`uint256` is the price and third parameters `bytes` is the callback called if approved. In callback we call `buyToken(uint256,address,uint256)`, first parameter is sticker pack id, second buyers address, and the last is the price.
