MLE Decryption Failing

I'll first start by saying I am not sure if this on the CyberSource Test API side or this gem. I reached out to their support but it's getting no where. We recently ran into an issue where MLE decryption stopped working when no changes or deployments were made on our side. We are on version 0.0.82 of this gem. We are hitting apitest.cybersource.com and attempting to call.

      payment_instance = CyberSource::PaymentsApi.new(api_client, config)

      response, status_code = payment_instance.create_payment(request_obj)

The error returned is CyberSource::ApiError Exception: Failure when receiving data from the peer. It works fine when enableResponseMleGlobally is set to false. We already tried swapping out our certs to no avail.

Any help would be appreciated! Below is our log output as well:

[2026-03-11 11:11:57] INFO   (MerchantConfig): START> =======================================
[2026-03-11 11:11:57] INFO   (MerchantConfig): Entered value for Key File Path : /path/to/resource/StagingCybersourceRequestMLE.p12
[2026-03-11 11:11:57] INFO   (MerchantConfig): Merchant Configuration:
{
  "runEnvironment"                           => "apitest.cybersource.com",
  "timeout"                                  => 10000,
  "authenticationType"                       => "JWT",
  "jsonFilePath"                             => "/path/to/resource/request.json",
  "keysDirectory"                            => "/path/to/resource",
  "keyFilename"                              => "StagingCybersourceRequestMLE",
  "logConfiguration"                         => {
    "enableLog"     => true,
    "loggingLevel"  => "DEBUG",
    "logDirectory"  => "log",
    "logFilename"   => "cybs",
    "maxLogSize"    => 10485760,
    "maxLogFiles"   => 5,
    "enableMasking" => true
  },
  "enableRequestMLEForOptionalApisGlobally"  => true,
  "requestMleKeyAlias"                       => "CyberSource_SJC_US",
  "enableResponseMleGlobally"                => true,
  "responseMlePrivateKeyFilePath"            => "/path/to/resource/StagingCybersourceResponseMLE.p12",
  "responseMlePrivateKeyFilePassword"        => "[REDACTED]",
  "responseMleKID"                           => "[REDACTED]"
}

[2026-03-11 11:12:04] INFO   (MLEUtility): Encrypting request payload
[2026-03-11 11:12:04] DEBUG  (MLEUtility): LOG_REQUEST_BEFORE_MLE:
{
  "clientReferenceInformation": {
    "code": "[REDACTED]",
    "partner": { "developerId": "[REDACTED]" }
  },
  "processingInformation": {
    "capture": true,
    "commerceIndicator": "internet"
  },
  "paymentInformation": {
    "customer": { "id": "[REDACTED]" }
  },
  "orderInformation": {
    "amountDetails": {
      "totalAmount": "5.17",
      "currency": "USD"
    }
  }
}
[2026-03-11 11:12:04] DEBUG  (MLEUtility): LOG_REQUEST_AFTER_MLE: { "encryptedRequest": "[ENCRYPTED_PAYLOAD]" }
[2026-03-11 11:12:04] INFO   (Authorization): Authentication Type: JWT
[2026-03-11 11:12:04] DEBUG  (MLEUtility): Validating responseMleKID for JWT token generation
[2026-03-11 11:12:04] DEBUG  (MLEUtility): P12/PFX file detected, checking if it is a CyberSource certificate
[2026-03-11 11:12:04] DEBUG  (MLEUtility): Successfully auto-extracted responseMleKID from CyberSource P12 certificate

[2026-03-11 11:16:05] INFO   (MLEUtility): Encrypting request payload
[2026-03-11 11:16:05] DEBUG  (MLEUtility): LOG_REQUEST_BEFORE_MLE:
{
  "clientReferenceInformation": {
    "code": "[REDACTED]",
    "partner": { "developerId": "[REDACTED]" }
  },
  "processingInformation": {
    "capture": true,
    "commerceIndicator": "internet"
  },
  "paymentInformation": {
    "customer": { "id": "[REDACTED]" }
  },
  "orderInformation": {
    "amountDetails": {
      "totalAmount": "5.17",
      "currency": "USD"
    }
  }
}
[2026-03-11 11:16:05] DEBUG  (MLEUtility): LOG_REQUEST_AFTER_MLE: { "encryptedRequest": "[ENCRYPTED_PAYLOAD]" }
[2026-03-11 11:16:05] INFO   (Authorization): Authentication Type: JWT
[2026-03-11 11:16:05] DEBUG  (MLEUtility): Validating responseMleKID for JWT token generation
[2026-03-11 11:16:05] DEBUG  (MLEUtility): P12/PFX file detected, checking if it is a CyberSource certificate
[2026-03-11 11:16:05] DEBUG  (MLEUtility): Successfully auto-extracted responseMleKID from CyberSource P12 certificate

Start with CyberSource::PaymentsApi#create_payment and the configuration for enableResponseMleGlobally, responseMlePrivateKeyFilePath, and responseMleKID. Reproduce the failure against apitest.cybersource.com with response MLE enabled, then compare it with the working disabled case. Done means identifying whether the client or CyberSource test API causes the peer failure and documenting or testing the confirmed fix.