Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/woohyun212/security-skill/constant-time-analysisnpx skills add woohyun212/security-skill --skill constant-time-analysisgit clone --depth 1 https://github.com/woohyun212/security-skillWrote 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.
[](https://agentmods.dev/skills/woohyun212/security-skill/constant-time-analysis)<a href="https://agentmods.dev/skills/woohyun212/security-skill/constant-time-analysis"><img src="https://agentmods.dev/badge/skills/woohyun212/security-skill/constant-time-analysis.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00022 | $0.02817 |
| Opus 5 | $0.00011 | $0.01409 |
| Sonnet 5 | $0.00004 | $0.00563 |
| Haiku 4.5 | $0.00002 | $0.00282 |
Grade A, and why
constant-time-analysis 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 6d 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.
How it starts
The opening of the file, as written. The whole thing — 233 lines — stays where its author put it; the contents beside it link to each section on GitHub.
What this skill does
Inspects cryptographic source code for timing side-channel vulnerabilities — flaws that allow an attacker to infer secret values by measuring how long operations take. Targets secret-dependent control flow (branches, early returns), variable-time memory accesses (table lookups indexed by secret bytes), and missing or broken constant-time comparison primitives. Combines grep-based static analysis with optional dynamic instrumentation via ctgrind, timecop, or dudect, and maps confirmed findings to MITRE ATT&CK techniques.
When to use
- Auditing AES, RSA, ECDSA, HMAC, or password-comparison routines for timing leaks
- Reviewing a custom crypto library or a vendor patch that touches sensitive comparison logic
- Verifying that a
memcmpreplacement is truly constant-time before production use - Checking that compiler flags (
-O2, LTO, PGO) have not optimized away carefully written constant-time code - Satisfying a security requirement that mandates constant-time operations for key material handling
Prerequisites
| Tool | Purpose | Install |
|---|---|---|
grep / ripgrep |
Static pattern search | pre-installed / apt install ripgrep |
objdump / gcc |
Disassembly, compilation | apt install binutils gcc |
valgrind + ctgrind |
Dynamic taint analysis | apt install valgrind + build ctgrind from source |
timecop |
Compile-time constant-time checker (C) | https://github.com/agl/ctgrind (see also timecop) |
dudect |
Statistical timing measurement | https://github.com/oreparaz/dudect |
Only grep/ripgrep and a compiler are required for the static analysis steps. Dynamic tools are optional but recommended for confirmation.
Inputs
| Variable | Description | Example |
|---|---|---|
TARGET_DIR |
Root directory of the crypto source to audit | ./src/crypto |
BINARY |
(optional) Compiled binary or object file for assembly inspection | ./build/libcrypto.so |
COMPILER_FLAGS |
Flags used to build the target | -O2 -march=native |
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.
- 6d ago First seen · 233 lines · 22 tokens per session scan A 53ba2a261b81
constant-time-analysis is a skill published in the GitHub repository woohyun212/security-skill (21 stars, last pushed 4mo ago), licensed MIT. It adds 22 tokens to every session and 2,817 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.
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