Certification Issuer

This package provides an easy and fast way to interact with the Certification Smart Contract.

Installation

npm install @klever/certificate-issuer

or

yarn add @klever/certificate-issuer

Basic Usage

To use the contract functions, you need to instantiate a Certificate object. You can do this by calling:

import { Certificate, IProvider } from '@klever/certificate-issuer'

const provider: IProvider = {
  api: 'https://api.testnet.klever.org',
  node: 'https://node.testnet.klever.org',
}

(...)

const certificate = new Certificate(contractAddress, provider, privateKey, salt)

Initialization Parameters

• contractAddress:
  The smart contract address on the blockchain. It is the unique identifier of the contract that will be used in the operations.

• provider:
  Object responsible for defining which network the application will interact with. Example networks:

  • mainnet (production network)
  • testnet (test network)
  • localnet (local development network)

• privateKey:
  The private key of the contract owner. This key must be the same one used to deploy the contract on the blockchain. It is required to sign and authorize transactions.

• salt:
  Optional value used to enhance encryption security. It serves as an extra piece of data (random or defined) that makes brute force attacks or data predictability more difficult.

Methods

create(inputs: object, expirationDate?: number): Promise<string>

Creates a new certificate based on the provided data.

• inputs: Object containing the certificate data (for example, name, course, date, etc).
• expirationDate: (Optional) Certificate expiration timestamp. Default is 0 (no expiration).
• Returns: The transaction hash of the certificate creation.

About the inputs, any object is accepted as long as after being flattened it results in 32 fields. For example:

{
  "student": {
    "name": "Alice Johnson",
    "email": "[email protected]",
    "wallet": "klever123xyz"
  },
  "course": {
    "title": "Full Stack Web Development",
    "description": "A complete program covering frontend and backend development.",
    "duration_hours": 120,
    "language": "English",
    "modules": [
      "HTML & CSS",
      "JavaScript",
      "Node.js & Express",
      "Databases"
    ]
  },
  "certificate": {
    "id": "CERT-2025-001",
    "issue_date": "2025-04-15",
    "expiration_date": "2028-04-15",
    "issuer": {
      "name": "Klever Academy",
      "website": "https://academy.klever.org"
    }
  }
}

The input will be converted inside the create method to:

{
  "student.name": "Alice Johnson",
  "student.email": "[email protected]",
  "student.wallet": "klever123xyz",
  "course.title": "Full Stack Web Development",
  "course.description": "A complete program covering frontend and backend development.",
  "course.duration_hours": 120,
  "course.language": "English",
  "course.modules.0": "HTML & CSS",
  "course.modules.1": "JavaScript",
  "course.modules.2": "Node.js & Express",
  "course.modules.3": "Databases",
  "certificate.id": "CERT-2025-001",
  "certificate.issue_date": "2025-04-15",
  "certificate.expiration_date": "2028-04-15",
  "certificate.issuer.name": "Klever Academy",
  "certificate.issuer.website": "https://academy.klever.org"
}

check(certificateId: string): Promise<boolean>

Checks if a certificate is active on the blockchain.

• certificateId: ID of the certificate to be checked.
• Returns: true if the certificate is valid, false otherwise.

⚠️ Revocation & Expiration Handling:
A certificate is considered invalid if it has a revokedDate set (greater than 0) and the current timestamp is greater than the expirationDate.
If expirationDate is 0, the certificate does not expire and must only be considered invalid if revoked.

proof(certificateId: string, key: string, value: string): Promise<boolean>

Validates whether a specific key/value pair exists and matches within the certificate.

• certificateId: The ID of the certificate.
• key: The flattened key corresponding to a field in the certificate.
  Important: The key must exactly match the flattened structure used when creating the certificate. For example, to validate a course module, you must use its precise flattened path like "course.modules.2".
• value: The expected value associated with the key.
• Returns: true if the key/value pair is valid and found in the certificate, false otherwise.

Example

If you want to verify the third module of the course from the certificate created in the create example, you must use the exact key:

{
  "course.modules.2": "Node.js & Express"
}

Using incorrect or unflattened keys such as course.modules or modules[2] will result in a failed validation.

revoke(certificateId: string): Promise<string>

Revokes a certificate on the blockchain.

• certificateId: ID of the certificate to be revoked.
• Returns: The transaction hash of the revocation.

changeExpirationDate(certificateId: string, expirationDate: number): Promise<string>

Changes the expiration date of a certificate.

• certificateId: ID of the certificate.
• expirationDate: New expiration date (timestamp).
• Returns: The transaction hash of the update.

getCertificateIdByHash(hash: string): Promise<string>

Retrieves the original certificateId from its hash.

• hash: Corresponding hash of the certificate.
• Returns: The certificate ID linked to the hash.

getEvents(certificateId: string): Promise<EventsResponse>

Gets the events associated with a certificate.

• certificateId: ID of the certificate.
• Returns: An EventsResponse object containing:
  • issuanceDate: Issuance date.
  • expirationDate: Expiration date.
  • revokedDate: Revocation date (0 if not revoked).

Used Types

EventsResponse

interface EventsResponse {
  issuanceDate: number
  expirationDate: number
  revokedDate: number
}