paymob-check-hmac

paymob-check-hmac is a command for Claude Code from PaymobAccept/Paymob-AI-Integration-Skill. It costs 16 tokens per session (1,165 once invoked), scanned A, original, MIT.

A command that checks Paymob webhook HMAC verification code against the integration specification. A webhook is an HTTP message sent automatically between services, and HMAC is a signature used to check that it was not altered.

In plain words
What is it for?
It is for reviewing webhook signature checks and confirming that invalid or unverifiable requests are handled safely.
Why use it?
It helps catch incorrect field ordering, digest handling, or unsafe failure behavior without exposing secret keys.

Command for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: reads .claude/ paths.

Runs only inside its plugin — its command needs a path that Claude Code sets for a plugin’s own hooks and for nothing else. Install the plugin, not this.

Part of the paymob-integration plugin — 1 skill, 3 commands, 1 MCP server shipped together

Good fit It is for reviewing webhook signature checks and confirming that invalid or unverifiable requests are handled safely.

Compare 6 commands from other repositories ↓
Install

Getting it into your agent

This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.

Claude Code
/plugin marketplace add PaymobAccept/Paymob-AI-Integration-Skill
Claude Code
/plugin install paymob-integration

Made for: Claude Code.

Or install paymob-integration, the plugin that ships this one along with the rest of its 1 skill, 3 commands, 1 MCP server.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for paymob-check-hmac

README.md
[![agentmods](https://agentmods.dev/badge/commands/paymobaccept/paymob-ai-integration-skill/paymob-check-hmac/github.svg)](https://agentmods.dev/commands/paymobaccept/paymob-ai-integration-skill/paymob-check-hmac)
Your own site
<a href="https://agentmods.dev/commands/paymobaccept/paymob-ai-integration-skill/paymob-check-hmac"><img src="https://agentmods.dev/badge/commands/paymobaccept/paymob-ai-integration-skill/paymob-check-hmac/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for paymob-check-hmac

Your own site · 80×15
<a href="https://agentmods.dev/commands/paymobaccept/paymob-ai-integration-skill/paymob-check-hmac"><img src="https://agentmods.dev/badge/commands/paymobaccept/paymob-ai-integration-skill/paymob-check-hmac.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 16 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,165 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00016 $0.01165
Opus 5 $0.00008 $0.00583
Sonnet 5 $0.00003 $0.00233
Haiku 4.5 $0.00002 $0.00117

Measured 10d ago against content hash 9ba64181e974, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

paymob-check-hmac scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

commands/paymob-check-hmac.md · 54 lines

How it starts

The opening of the file, as written. The whole thing — 54 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Audit the user's Paymob webhook HMAC verification code: $ARGUMENTS

Non-negotiable ground rules for this command, before anything else:

  • Never ask the user to paste their HMAC secret, API key, or Secret Key into this conversation.
  • Never read a .env file's actual secret value, and never echo, print, or write any secret into chat output, logs, or a file you create.
  • The default mode is a static code audit — no computation is required to complete it.
  • Never audit the field order, digest, or callback shape from memory. This command deliberately carries no copy of the spec. If you cannot read hmac-verification.md, you cannot do this audit — say so and stop. An audit performed from recall can pass a wrong field order as correct, which is the exact failure this command exists to catch: HMAC verification that looks verified and silently is not.

Step 0 — locate the spec

hmac-verification.md lives in the skill's references/ directory. Use the first of these that exists:

  1. ${CLAUDE_PLUGIN_ROOT}/skills/paymob-integration/references/ — plugin install
  2. ~/.claude/skills/paymob-integration/references/ — personal skill install. ~ is the user's home directory; on Windows expand it yourself (%USERPROFILE%\.claude\skills\…), since a literal ~ will not resolve there.
  3. skills/paymob-integration/references/ — repository checkout, relative to the working directory. This only resolves if the user happens to be working inside the skill repo, so treat path 2 as the reliable one for a personal install.

${CLAUDE_PLUGIN_ROOT} is substituted only for plugin installs. If you see it unexpanded, you are not in one — use path 2 or 3. If none resolve, search for hmac-verification.md under any paymob-integration directory. Confirm you have actually read the file before starting Step 2.

Step 1 — locate the code

If $ARGUMENTS names a path, start there. Otherwise search for the callback route bound to notification_url / the hmac query parameter, or for PAYMOB_HMAC_SECRET usage.

Read the full file on GitHub · 54 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 10d ago First seen · 54 lines · 16 tokens per session scan A 9ba64181e974

Subscribe to this mod's changes

paymob-check-hmac is a command published in the GitHub repository PaymobAccept/Paymob-AI-Integration-Skill (30 stars, last pushed 26d ago), licensed MIT. It adds 16 tokens to every session and 1,165 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.