Improve signature validation#3998
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Pull request overview
This PR tightens signature/password comparison logic by switching to constant-time equality checks to reduce timing side-channel leakage during HMAC/JWT verification and LDAP password comparison.
Changes:
- Use
MessageDigest.isEqual(...)for constant-time comparisons in multiple authentication/signature validation paths. - Harden
signed_requestclaim extraction to reject missing/unknown signing algorithms. - Decode and compare HMAC/JWT signatures as bytes rather than using
String.equals(...).
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated 5 comments.
| File | Description |
|---|---|
server/src/main/java/org/cloudfoundry/identity/uaa/provider/oauth/ExternalOAuthAuthenticationManager.java |
Tightens signed_request algorithm enforcement and uses constant-time signature comparison (but introduces a Java compilation issue). |
server/src/main/java/org/cloudfoundry/identity/uaa/provider/ldap/PasswordComparisonAuthenticator.java |
Replaces Arrays.equals with constant-time comparison for local LDAP password byte checks (leaves an unused import). |
server/src/main/java/org/cloudfoundry/identity/uaa/oauth/jwt/UaaMacSigner.java |
Uses constant-time comparison for legacy HMAC JWT verification and introduces an opportunity to check supported algorithms before signing (also contains a typo in an exception message). |
Comment on lines
+662
to
+666
| if (!"HMAC-SHA256".equals(algorithm)) { | ||
| log.debug("Missing or unknown algorithm was used to sign request! No claims returned."); | ||
| return null; | ||
| } | ||
| //check if data is signed correctly | ||
| if (!hmacSignAndEncode(signedRequests[1], secret).equals(signature)) { | ||
| log.debug("Signature is not correct, possibly the data was tampered with! No claims returned."); | ||
| // check if data is signed correctly using constant-time comparison |
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