using their account via the payment gateway.

      Confidentiality: As mentioned in the previous question, data confidentiality means, no one except the authorized person i.e., one who has all the credentials for that account has access to the payment. The payment gateway act as the middleman between the person and banker, So data confidentiality should be given top priority in a transaction.

Degree of importance:

If someone can access the payment details while making the transaction(it’s highly non-practical as most payment gateway systems use 128-bit encryption and SHA-256 hashing) he can wipe off your account. So Data confidentiality is always a top priority. 

Data Integrity:

Payment or transaction of a user always depends on the accuracy of the methods and services of the payment gateway system, any small miscommunication or tampering data while in the communication with the bank account will result in leaking of confidential information which further leads to loss of amount for the user.

Degree of importance:

Data integrity should always be achieved while making the transaction through the payment gateway.

Availability:

The payment gateway system should always be available to the intended customer  otherwise, the infrastructure of the payment gateway would serve no purpose. If any firm fails to do so it would impact the company’s reputation and economic well-being.

Degree of importance:

It is less concerned in the user's perspective, as it would not cause any stealing of money or information. But from the organization's perspective, it would dent their reputation and impact the revenues of a company. So it would be a major concern for the provider of the payment gateway system.