UPI Consumer Stack

Credblock Request Body

When interacting with certain APIs, it is essential to provide a credblock string as part of the request body. The credblock serves as an encrypted string, meticulously generated by the NPCI Common Library. This encrypted string is employed to validate the MPIN (Mobile Personal Identification Number) with the customer's bank.

The credblock string encompasses one or more data blocks, each tailored to the specific requirements of the API. Within these data blocks, three crucial fields are included: data, subtype, and type.

  • Data Field: The data field is a container for multiple key-value pairs, each playing a unique role in the transaction. The following keys are commonly found within the data field:

    1. "type"

    2. "skey"

    3. "pid"

    4. "ki"

    5. "hmac"

    6. "code"

    7. "encryptedBase64String”

  • Subtype field: The subtype value specifies the nature or category of the data being processed, providing additional context for the transaction. It may contain one of the following values:

    • SMS

    • MPIN

    • NMPIN

    • ATMPIN

    • CARDDETAILS

    • IDENTITY

    • SIGNATURE

  • Type Field: The type value delineates the specific type of data encapsulated in the block, offering clarity on the purpose and usage of the information. The data block may contain one of the following values:

    • OTP

    • PIN

    • CARD

    • DEVICE

    • ARQC