Use constant-time comparison and a cached HMAC for webhook signature verification

[RUKAYAT-CODER]

Background

BackEnd/src/modules/webhooks/webhooks.service.ts re-derives the HMAC and compares signatures with a plain string comparison on every webhook, adding avoidable per-request CPU and a timing side-channel on the verification hot path.

Implementation Plan

• Replace the string equality check with crypto.timingSafeEqual over equal-length buffers in webhooks.service.ts
• Reuse a cached/precomputed HMAC key or instance instead of re-deriving the secret per request
• Add benchmarks/metrics capturing before/after impact
• Add regression tests where applicable
• Document the change

Acceptance Criteria

• Measurable performance/efficiency improvement demonstrated with before/after numbers
• No regression in existing functionality
• Tests pass and code follows project standards
• Change is documented

[pixels26]

Hi Maintainer , I've carefully gone through your codebase and understand what's needed to fix it, please assign

[Adeyemi-cmd]

Hello maintainer. ii would love to work on this

[Bayovictor]

@Bayovictor has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi, Please I would like to work on this issue.

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[Akanjioladayo5]

@Akanjioladayo5 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Interested in working on this. I'll ensure the implementation is clean, tested, and aligned with project standards.

I'd love to work on this issue. I'll keep the implementation simple, clean, and well-tested.

I understand the expected outcome and would love to work on this. I'll provide a solution that satisfies the acceptance criteria.

I'd be glad to handle this issue. I'll keep the implementation concise, maintainable, and well-documented.

I've reviewed the issue thoroughly and can start working on it right away. Looking forward to contributing

Interested in working on this issue. I understand the requirements and can deliver a solution that meets the expected outcome.

I'd love to work on this. I understand the requirements and can handle the implementation.

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[Obaara293]

@Obaara293 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi maintainer, I've reviewed the issue and I've recognized the solution, kindly assign this to me to get the best result.

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[bellofuad34-ctrl]

@bellofuad34-ctrl has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi Maintainer, I’m interested in contributing to this issue. I have hands on experience with similar tasks and a solid technical background, and I’m confident I can make a meaningful contribution. I’m available to start immediately and would be happy to discuss the approach and next steps.

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