Gift Cards

Encoding and decoding URLs for gift cards

Getting Gift Card Actual Balance: When distributing a gift-card several parameters are provided to the user including the spending key, birth index, balance, pool address and so on. The easiest way to achieve this is to encode these parameters into the URL. The following methods are intended for creating and parsing a gift card.

Use gift card codes with care. Anyone who knows the code has full access to the gift card funds.

Encoding Gift-Card Parameters

To create gift-card URL code invoke the following method:

async codeForGiftCard(giftCard: GiftCardProperties): Promise<string>

Parameters

giftCard - a GiftCardProperties object which contains all needed parameters to encode

Returns

Promise returns Base58-encoded string which can be injected into the redeeming URL

Example

const gk: GiftCardProperties = {
    sk: new Uint8Array(
        [ 40, 169, 173, 13, 42, 145, 224, 222, 213, 124, 226, 142, 126, 241, 6, 1,
          42, 133, 48, 12, 96, 66, 213, 158, 112, 225, 75, 198, 172, 82, 148, 3 ]
    ),
    birthIndex: 533888,
    poolAlias: 'BOB-sepolia',
    balance: 10000000000n
};
const code = await zkClient.codeForGiftCard(gk);
const baseURL = 'https://staging--zkbob.netlify.app';
console.log(`Redeem gift-card with: ${baseURL}/?gift-code=${code}`);
// output: Redeem gift-card with: 
// https://staging--zkbob.netlify.app/?gift-code=QvHXyAF2ykRCSTCwiLJbGGJVjJX7M8Xp5vfNNLaiEvwV8BQfYBeR6ivtY7svMpPyCsL6huTHpB

Decoding a Gift-Card Code

Use the following method to retrieve a gift-card from the code or URL containing the code:

async giftCardFromCode(code: string): Promise<GiftCardProperties>

Related Methods

• giftCardBalance(giftCard: GiftCardProperties)
• redeemGiftCard(giftCard:GiftCardProperties, preferredProvingMode?: ProverMode)

Parameters

code - a gift-card code or URL contained code within the gift-code query parameter.

Returns

Promise returns the GiftCardProperties of a decoded card. Errors may return InternalError.

Example

const url = 'https://staging--zkbob.netlify.app/?gift-code=QvHXyAF2ykRCSTCwiLJbGGJVjJX7M8Xp5vfNNLaiEvwV8BQfYBeR6ivtY7svMpPyCsL6huTHpB';
try {
    const gk = await zkClient.giftCardFromCode(url);
    console.log(`This card with balance ${gk.balance} intended for ${gk.poolAlias} pool`);
} catch (err) {
    console.log(`An error was occured while parsing the gift-card: ${err.message}`);
}
// output: This card with balance 100000000000 intended for BOB-sepolia pool