Fix webhook toleranceSeconds unit mismatch - #142
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The ts value from the x-signature header is in seconds; now() returns milliseconds. Multiply ts by 1000 before computing drift to avoid false TIMESTAMP_OUT_OF_TOLERANCE rejections. Update existing tolerance tests and add a new test that signs with a seconds-based timestamp and asserts it passes with tolerance_seconds=3600.
Diego Barajas (barajas-d)
approved these changes
Aug 3, 2026
2 tasks
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Summary
Fixes two bugs in WebhookSignatureValidator reported in issues #458 and #459:
Bug #458 — toleranceSeconds comparing seconds against milliseconds
The `ts` value in the `x-signature` header is in seconds (e.g. `1704908010`), but the clock was read in milliseconds. This made any `toleranceSeconds` value effectively reject every legitimate webhook notification.
Fix: Convert `ts` to milliseconds before computing drift.
Bug #459 — RangeError on multibyte v1 hash (Node.js only)
`constantTimeEquals` compared string `length` (characters) but `Buffer.from()` operates on bytes. A 64-character v1 with one multibyte character has 65 bytes, passing the guard and throwing `RangeError` instead of `InvalidWebhookSignatureError`.
Fix: Use `Buffer.byteLength()` in the length guard.
Test plan
Closes #458, Closes #459
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