Subresource Integrity (SRI) Hash Generator

What is Subresource Integrity?

Subresource Integrity (SRI) is a security feature that enables browsers to verify that resources they fetch (like scripts or stylesheets, often from CDNs) are delivered without unexpected manipulation. It works by using cryptographic hashes specified in a webpage. If the fetched file doesn't match its hash, the browser refuses to execute it, protecting your users from potentially malicious code.

SRI vs. HTTPS

HTTPS encrypts data in transit, ensuring the connection between the user and the server is secure and private. SRI, on the other hand, verifies the integrity of the file's content itself, after it's delivered. HTTPS protects the pipe, SRI protects what comes through the pipe. They are complementary: HTTPS prevents man-in-the-middle attacks on the connection, while SRI protects against compromised CDN or third-party server content, even if served over HTTPS.

Risks of Not Using SRI

Without SRI, if a third-party server or CDN hosting your external resources (like JavaScript libraries) is compromised, attackers can inject malicious code into those files. This code would then run on your users' browsers, potentially leading to:

• Data theft (credentials, personal information)
• Website defacement or unwanted ads
• Malware distribution
• Loss of user trust and reputational damage

Does Hash Type Matter?

Yes, the hash type matters. Stronger cryptographic hash functions (like SHA-384 or SHA-512) are recommended over older ones like SHA-256, as they are more resistant to collision attacks (though this is less of a direct threat for SRI's main purpose). Browsers must support the hash algorithm you choose. The key is that the hash accurately and securely represents the file's content, ensuring that even a tiny modification to the file results in a completely different hash, thus failing the integrity check.