All card numbers are encrypted at rest with AES-256. Decryption keys are stored on separate machines. None of Stripe’s internal servers and daemons can obtain plaintext card numbers but can request that cards are sent to a service provider on a static allowlist. Stripe’s infrastructure for storing, decrypting, and transmitting card numbers runs in a separate hosting environment, and doesn’t share any credentials with Stripe’s primary services (API, website, etc.).