The API uses Bearer (Token) Authentication to authenticate any request. These tokens are JSON Web Tokens (JWT) which need to be created server side by your application.

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Authenticate an API call

Every API endpoint that requires authentication expects an authorization HTTP-header with a signed JWT token as its value (prefixed with bearer).

curl -i -X GET "https://api.example.gr4vy.app/transactions" \
    -H "authorization: bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c"

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Create an API key

To sign a JWT, you’ll need to create a new API key. Please contact a Wpay representative to request API key generation. You can store the API key with your code or store it in a secure environment accessible to your application.

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Algorithm

Our API supports 2 algorithms for signing JWTs: ECDSA and RSA. We recommend you use ECDSA unless your environment does not support this stronger and newer algorithm. The RSA algorithm is available for those environments that do not support ECDSA. RSA keys provide considerably less security for the same key size and are currently not supported by our SDKs.

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JWT using SDK

JWTs can be generated using one of our SDKs, or manually using a compatible JWT library. For your convenience we recommend using one of our SDKs as they make the process a lot easier.

First, install the SDK.

npm install @gr4vy/node --save
# or: yarn add @gr4vy/node

Then, initialize the client with your API key and generate the token.

const fs = require("fs");
const { Client } = require("@gr4vy/node");
const key = String(fs.readFileSync("./private.key"));

const client = new Client({
  gr4vyId: "example",
  privateKey: key,
});

const token = client.getBearerToken(["transactions.read"]);

The Gr4vy ID is the unique identifier for your instance. Together with the environment (sandbox or production) it is used to connect to the right APIs.

The possible values for your ID are one of wpay, wpay1, wpay2, or wpay3. We will inform you in which instance your account has been set up.

Each SDKs will automatically handle authentication for any server-to-server calls. Generating a token for use outside of the SDK can be useful in a micro-services architecture. In all other situations use the built-in SDK methods for making an API call.

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Manual JWT

In some cases you might not want to use one of our SDKs, or an SDK in your language might not be available. In those cases you can construct, and sign the JWT with one of the many libraries available on jwt.io.

At the high level a JWT is build up out of 3 pieces:

  • A header defining the algorithm and key used to create the JWT.
  • A set of claims that define the token’s scope and other permissions.
  • A cryptographic signature based on the header and the claims, signed using your private key.

Combine, these 3 pieces make up the JSON Web Token (JWT). See jwt.io for more details on the specification and available libraries for generating JWTs.

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JWT header

The JWT header defines the type of encryption algorithm as well as the private key used to generate the signature.

{
  "typ": "JWT",
  "alg": "ES512", // OR RS512 depending on your key
  "kid": "d757c76acbd74b56"
}

The typ and alg are fixed and do not allow for other values. The kid is the ID of your private key, which you can find in the Integrations panel of your dashboard.

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JWT claims

The claims define when the token was created and what access it has.

{
  "iss": "My JWT Generation Tool",
  "nbf": 1607976645,
  "exp": 1607976314,
  "jti": "0fe1fb1b-2f7e-4c8d-b0eb-aae5d0ec98f7",
  "scopes": ["transactions.read"],
  "embed": {
    "amount": "200",
    "currency": "AUD",
    "buyer_id": "d757c76a-cbd7-4b56-95a3-40125b51b29c",
    "metadata": { "key": "value" },
    "cart_items": [
      {
        "name": "Joust Duffle Bag",
        "quantity": "1",
        "unit_amount": "9000",
        "tax_amount": "0"
      }
    ]
  }
}

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Claims

The API supports the following JWT claims.

DescriptionRequired
issA unique ID that represents your code making this call. This helps identify what library made an API call to Gr4vy.Yes
nbfThe UNIX timestamp (in seconds) that this token was created at.Yes
expThe UNIX timestamp (in seconds) that this token expires at.Yes
iatAn optional UNIX timestamp (in seconds) for your internal use to indicate when the token was issued.No
jtiA random unique ID used for cryptographic entropy. This needs to be unique for each JWT.Yes
scopesA list of scopes that give this token access to the API.Yes
embedA dictionary of key-value pairs used to pin the amount, currency, and buyer info for use in Embed.No
checkout_session_idThe ID of a checkout session. This can be used to tie multiple transactions together as having originated from the same session.No

Timestamps

Please be aware that the nbf, exp, and iat values are UNIX timestamps defined as seconds since January 1st, 1970 (UTC). Some programming languages will return UNIX timestamps as milliseconds, requiring the removal of the last 3 digits.

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Scopes

The API supports the following values for the scopes claims.

ScopeDescription
*.readAllows read-access to any resource. This is used by default in the SDKs
*.writeAllows write-access to any resource. This is used by default in the SDKs. This does not also allow read access.
{resource_name}.readAllows read-access to a type or resource. For example, payment-services.read enabled read-access for buyers data.
{resource_name}.writeAllows write-access to a type or resource. For example, payment-services.write enabled write-access for buyers data. This does not also allow read access.
embedA scope that represents all the access needed by Embed.

The following resource names are recognized. Please see the reference documentation for more details as to what scope is required per endpoint.

  • anti-fraud-services
  • api-logs
  • buyers
  • buyers.billing-details
  • card-scheme-definitions
  • checkout-sessions
  • connections
  • digital-wallets
  • flows
  • payment-methods
  • payment-method-definitions
  • payment-options
  • payment-service-definitions
  • payment-services
  • reports
  • transactions

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Signature & assembly

Finally, the JWT signature is generated by appending the Base64 encoded header and claims (separated with a .) and run it through the key’s algorithm.

ECDSASHA512(
  base64UrlEncode(header) + "." +
  base64UrlEncode(payload),
  public_key,
  private_key
)

The assembled JWT is then formed by appending the Base64 encoded header, claims, and signature separated by a full stop.

base64UrlEncode(header) + "." + base64UrlEncode(payload) + "." + base64UrlEncode(signature)