[spark-compete] fix(security): prevent timing side-channel in constantTimeEquals length comparison

[ifeoluwaaj]

spark-compete Packet

"evidence.forbidden": [
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    "type": "bug",
    "severity": "MEDIUM",
    "title": "fix(security): prevent timing side-channel in constantTimeEquals length comparison",
    "actual_behavior": "Before fix: return leftBuffer.length === rightBuffer.length && timingSafeEqual(leftBuffer, rightBuffer);",
    "expected_behavior": "After fix: return timingSafeEqual(leftPadded, rightPadded) && leftBuffer.length === rightBuffer.length;",
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  "proposed_fix": {
    "approach": "fix(security): prevent timing side-channel in constantTimeEquals length comparison",
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      "src/lib/server/hosted-ui-auth.ts",
      "src/lib/server/mcp-auth.ts"
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    "url": "https://github.com/vibeforge1111/vibeship-spawner-ui/pull/857"
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Bug Summary

fix: resolve issue in vibeship-spawner-ui

Severity: MEDIUM

Expected:

Root Cause

The bug was identified through code review. See PR diff for specific details.

Team: Sequence

Role	Username	GitHub	Device
LLM Device Holder	@ifesn	ifeoluwaaj	VPS
Member	@micc9ee	micc9ee	-
Member	@londitshabalala	londitshabalala	-

return leftBuffer.length === rightBuffer.length && timingSafeEqual(leftBuffer, rightBuffer);

## Fix

Necessary code changes applied to resolve the bug.

Applied fix:
```python
	// Use the longer length to prevent timing leak on length comparison

Before (The Bug)

	return leftBuffer.length === rightBuffer.length && timingSafeEqual(leftBuffer, rightBuffer);

After (The Fix)

	// Use the longer length to prevent timing leak on length comparison
	const maxLen = Math.max(leftBuffer.length, rightBuffer.length);
	const leftPadded = Buffer.alloc(maxLen, 0);

Testing

• • Verified existing test suite passes
• Manual verification: fix(security): prevent timing side-channel in constantTimeEquals length comparison

Files Changed

File	Change Summary
src/lib/server/hosted-ui-auth.ts
src/lib/server/mcp-auth.ts

Risk Notes

• Surface changed: src/lib/server/hosted-ui-auth.ts
• Risk level: Low - minimal code changes
• Reviewers should verify: Fix handles edge cases correctly

Duplicate Notes