Integration security guide

Anyone involved with the processing, transmission, or storage of card data must comply with the Payment Card Industry Data Security Standards (PCI DSS). Stripe has been audited by an independent PCI Qualified Security Assessor (QSA) and is certified as a PCI Level 1 Service Provider. This is the most stringent level of certification available in the payments industry.

PCI compliance is a shared responsibility and applies to both Stripe and your business. When accepting payments, you must do so in a PCI compliant manner. The simplest way for you to be PCI compliant is to never see (or have access to) card data at all. Stripe makes this easy for you as we can do the heavy lifting to protect your customers’ card information. You can simplify your PCI compliance as long as you:

• Use one of our recommended payments integrations to collect payment information, which is securely transmitted directly to Stripe without it passing through your servers
• Serve your payment pages securely using Transport Layer Security (TLS) so that they make use of HTTPS
• Review and validate your account’s PCI compliance annually

Validating your PCI compliance

All Stripe users must validate their PCI compliance annually. Most users can do this with a Self-Assessment Questionnaire (SAQ) provided by the PCI Security Standards Council. The type of SAQ depends on how you integrated Stripe and which of the methods below you use to collect card data. Certain methods may require you to upload additional PCI documentation to us. If this is necessary, we’ll notify you in the Dashboard. If you’re using more than one of the methods below, there’s no need to upload multiple SAQs. We can determine which SAQ covers all the ways you’ve integrated with Stripe.

If you’re not sure how to prove that your business is PCI compliant (for example, your integration was built by a third-party), Stripe determines what documentation might be required based on how you’re processing payments and provides this information in your account’s compliance settings.

Using TLS and HTTPS

TLS refers to the process of securely transmitting data between the client—the app or browser that your customer is using—and your server. This was originally performed using the SSL (Secure Sockets Layer) protocol. However, this is outdated and no longer secure, and has been replaced by TLS. The term SSL continues to be used colloquially when referring to TLS and its function to protect transmitted data.

Payment pages must make use of a modern version of TLS (for example, TLS 1.2) as it significantly reduces the risk of you or your customers being exposed to a man-in-the-middle attack. TLS attempts to accomplish the following:

• Encrypt and verify the integrity of traffic between the client and your server
• Verify that the client is communicating with the correct server. In practice, this usually means verifying that the owner of the domain and the owner of the server are the same entity. This helps prevent man-in-the-middle attacks. Without it, there’s no guarantee that you’re encrypting traffic to the right recipient.

Additionally, your customers are more comfortable sharing sensitive information on pages visibly served over HTTPS, which can help increase your customer conversion rate.

If need be, you can test your integration without using HTTPS, and enable it once you’re ready to accept live charges. However, all interactions between your server and Stripe must use TLS 1.2 (i.e, when using our libraries).

Setting up TLS

A digital certificate—a file issued by a certification authority (CA)—is needed in order to use TLS. When installed, this certificate assures the client that it’s really communicating with the server it expects to be talking to, not an impostor. You should get a digital certificate from a reputable certificate provider, such as:

• Let’s Encrypt
• DigiCert
• NameCheap

Certificates can vary in cost, depending on the type of certificate and provider. Let’s Encrypt is a certificate authority that provides certificates for free.

Conceptually, setting up TLS is very straightforward: a certificate is purchased from a suitable provider, and then your server is configured to use it. The actual process does tend to be somewhat complex, and we recommend you follow the installation guide of the provider you use.

As TLS is a complex suite of cryptographic tools, it’s easy to miss a few details. We recommend using the SSL Server Test by Qualys SSL Labs to make sure you have everything set up in a secure way.

Additional security considerations

It can be a security risk to include JavaScript from other sites as your security becomes dependent on theirs. If they’re ever compromised, an attacker may be able to execute arbitrary code on your page. In practice, many sites make use of JavaScript for services like Google Analytics, even on secure pages. Nonetheless, it’s something to be aware of, and ideally minimize.

If you’re making use of webhooks, we recommend using TLS for the endpoint to avoid traffic being intercepted and the notifications altered (sensitive information is never included in a webhook event).

While complying with the Data Security Standards is important, it shouldn’t be where you stop thinking about security. Some good resources to learn about web security are:

• OWASP
• SANS
• NIST

Out-of-scope card data that you can safely store

Stripe returns non-sensitive card information in the response to a charge request. This includes the card type, the last four digits of the card, and the expiration date. This information is not subject to PCI compliance, so you are able to store any of these properties in your database. Additionally, you can store anything returned by our API.

Content Security Policy

If you have deployed a CSP, the full set of directives that Stripe.js and Checkout require are:

trustedTypes.createPolicy('default', {
  createScriptURL: (input) => {
    if (new URL(input).origin === 'https://js.stripe.com') {
      return input;
    }
    return undefined;
  }
});