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Case studies

Payment approval built into the phone.

A transaction-signing SDK that lets customers review and approve payments securely on their own devices, without leaving the bank's existing application.

Client withheld under NDA

Challenge

SMS one-time codes expose payment approval to delivery failures, interception and SIM-related fraud. The bank needed a stronger approval method that could run inside its existing application and bind each confirmation to the specific payment being authorised.

What we built

  • An SDK that generates and stores a unique cryptographic key securely on the customer's device using Secure Enclave or StrongBox.
  • Push and QR-based approval flows that display the payment details before the customer confirms with biometrics.
  • Dynamic linking that binds the signature to the payment amount and recipient.
  • Device-integrity and anti-tampering checks performed before a signing request is accepted.

Business outcome

Customers can review and approve payments inside the bank's existing app using biometric confirmation instead of an SMS code.

Each approval is cryptographically linked to the payment amount and recipient, giving the bank a clear record of exactly what the customer authorised. This supports PSD2 dynamic-linking requirements and provides stronger evidence for compliance reviews and payment disputes.

The SDK added this capability without requiring the bank to replace or rebuild its application.

Capabilities

  • Transaction signing
  • On-device security
  • PSD2 SCA
  • Dynamic linking
  • Mobile SDK

Related work

Describe your challenge.

Early idea or system already in production. Both are worth a conversation.

  • Built and run by our senior team.
  • Confidential from the first call, NDA as standard.

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