Auth Stream Access (ASA)

Learn about providing your own authorization rules.

Authorization Stream Access (ASA) provides the ability to make custom transaction approval decisions through an HTTP interface to the ISO 8583 message stream.

ASA requests are delivered as an HTTP POST during authorization. The ASA request body adheres to the Lithic transaction schema, with some additional fields added for use in decisioning. A response should be sent with HTTP response code 200 and the approval decision in the response body. This response is converted by Lithic back into ISO-8583 format and forwarded to the network.


Testing in sandbox

In sandbox, users can self-enroll and disenroll in ASA. In production, onboarding requires manual approval and setup.


Pre-ASA auth request checks

For ASA-enabled customers, Lithic will only perform very basic pre-authorization checks before sending the request out (decrypt EMV cryptogram, validate PAN, validate CVV/PIN if present). For example, we won't check auth rules such as MERCHANT_LOCKED or spending limits. You must supply your own auth rules.

Lithic will not send ASA requests to your endpoint if the message fails basic pre-authorization checks. For a list of all pre-authorization checks, please reference Transaction.result.

Set up an ASA responder in under 10 minutes!

Full details on responding to ASA requests follow, but to get you up and running quickly we’ve also provided sample application for creating an auth stream access webhook with AWS API Gateway and Lambda, managed via AWS Serverless Application Model (SAM).

  1. NodeJS example:
  2. Python example:


Lithic Request

Similar to Transaction object in Transaction Webhooks with additional properties.

  "amount": Integer,
  "acquirer_fee": Integer,
  "authorization_amount": Integer,
  "avs": {
      "address": String,
      "zipcode": String
  "card": Card,
  "created": String,
  "events": [
  "funding": [
          "amount": Integer,
          "token": String,
          "type": String
  "merchant_amount": Integer,
  "merchant_currency": String,
  "merchant": Merchant,
  "network": String,
  "pos": {
      "terminal": {
          "attended": Boolean,
          "operator": String,
          "on_premise": Boolean,
          "card_retention_capable": Boolean,
          "pin_capability": String,
          "type": String,
          "partial_approval_capable": Boolean
      "entry_mode": {
          "pan": String,
          "pin_entered": Boolean,
          "cardholder": String,
          "card": String
  "settled_amount": Integer,
  "status": String,
  "token": String
acquirer_feeFee (in cents) assessed by the merchant and paid for by the cardholder. Will be zero if no fee is assessed. Rebates may be transmitted as a negative value to indicate credited fees.
amountAuthorization amount (in cents) of the transaction. This may change over time.
authorization_amountThe base transaction amount (in cents) plus the acquirer fee field. This is the amount the issuer should authorize against unless the issuer is paying the acquirer fee on behalf of the cardholder.
avsContains address validation (AVS) information entered by the client to be verified by the issuer.
cardSee Cards definition.
createdDate and time when the transaction first occurred.
events (Issuing) A list of all events that have modified this transaction.
fundingA list of objects that describe how this transaction was funded, with the amount represented in cents. A reference to the funding source for the card that made this transaction may appear here and the token will match the token for the funding source in the card field. If any promotional credit was used in paying for this transaction, its type will be PROMO.
merchantSee Merchant definition.
merchant_amountThe amount that the merchant will receive, denominated in merchant_currency and in the smallest currency unit. Note the amount includes acquirer_ fee, similar to authorization_amount. It will be different from authorization_amount if the merchant is taking payment in a different currency.
merchant_currencyISO 4217 alpha 3 code for the currency of the transaction.
networkCard network of the authorization. Can be INTERLINK, MAESTRO, MASTERCARD, VISA, or UNKNOWN.
posSee Point of Sale definition.
settled_amountAmount (in cents) of the transaction that has been settled. This may change over time.
statusAUTHORIZATION, FINANCIAL_AUTHORIZATION, and BALANCE_INQUIRY indicates that this request requires an ASA response body in HTTP 200 response. FINANCIAL_AUTHORIZATION is a final single-message transaction with no subsequent clearing, BALANCE_INQUIRY is a $0 authorization that should prompt a response with the appropriate balance.
tokenGlobally unique identifier.

Client Response

  "result": String,
  "token": String,
  "avs_result": String,
  "balance": {
      "amount": Integer,
      "available": Integer
resultAPPROVED to accept the authorization. Any other response will decline the authorization. See ASA Response Result for possible values.
tokenThe transaction token from the ASA request.
avs_result (optional)The ASA client may return an address verification (AVS) match indicator for evaluation by the acquirer. See AVS Response Result for possible values. The merchant can choose whether to submit the transaction in the case of an approval with AVS failure.
balance (optional)Respective available amount and settled amount values (in cents). These values can be used by merchants for authorization decisions as well as balance display at point of sale or ATM.

Response Guidelines

Response Time

The request timeout is configurable per request, with a default of 5 seconds. Response before the timeout does not guarantee that the authorization will succeed.

AVS Matching

Address verification (AVS) checks two pieces of information, the postal code and the billing street address. Responding with AVS is optional. If AVS is present and a response is not received, Lithic will return AVS validated.
If AVS attributes aren’t included in the authorization, any AVS response result will be ignored.

Returned Balances

BALANCE_INQUIRY ASA messages require a settled and available amount to be returned.

  • amount represents the balance held on the card.
  • available represents the balance available for the cardholder to spend. This is calculated as the settled amount minus any pending authorizations on the card.

If no balance is returned, Lithic will return $0 for both attributes.


Point of Sale

terminal.attendedTrue if a clerk is present at the sale.
terminal.on_premiseTrue if the sale was made at the place of business (vs. mobile).
terminal.operatorThe person that is designed to swipe the card, possible values: CARDHOLDER, CARD_ACCEPTOR, ADMINISTRATIVE.
terminal.partial_approval_capableTrue if the terminal is capable of partial approval. Partial approval is when part of a transaction is approved and another payment must be used for the remainder. Example scenario: A $40 transaction is attempted on a prepaid card with a $25 balance. If partial approval is enabled, $25 can be authorized, at which point the POS will prompt the user for an additional payment of $15.
terminal.pin_capabilityStatus of whether the POS is able to accept PINs, possible values: CAPABLE, INOPERATIVE, NOT_CAPABLE, UNSPECIFIED.
terminal.typePOS type, see POS Type for possible values.
entry_mode.cardCard status, possible values: PRESENT, NOT_PRESENT.
entry_mode.cardholderCardholder status, see Cardholder Status for possible values.
entry_mode.panMethod of entry for the PAN, see Method of Entry for possible values.
entry_mode.pin_enteredTrue if the PIN was entered.


Partial approval is currently not supported.

POS Type

  • ATM
  • ECR
  • MICR
  • PDA

Method of Entry

  • ICC
  • OCR

Cardholder Status


ASA Response Result

Decline reasonDescription
ACCOUNT_INACTIVESame as CARD_PAUSED, will be deprecated in future versions.
AVS_INVALIDPrevent acquirers from approving the transaction despite incorrect AVS. Note: AVS response is not required for this decline type.
CARD_CLOSEDCard is permanently closed. Using CARD_CLOSED will result in subsequent authorizations being declined on the ASA client's behalf.
CARD_PAUSEDCard is not yet activated or in a paused state.
INSUFFICIENT_FUNDSUser has insufficient funds. Acquirers may retry the transaction at a later time.
UNAUTHORIZED_MERCHANTCan be used for restricted MCCs, countries, or transaction types (e.g. money transfer transactions).
VELOCITY_EXCEEDEDTransaction exceeds issuer-set velocity limits. Acquirers may retry the transaction at a later date.

AVS Response Result


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