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 skills add marduk191/qwen3_mcp --skill constant-time-testinggit clone --depth 1 https://github.com/marduk191/qwen3_mcpWrote 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/marduk191/qwen3_mcp/constant-time-testing)<a href="https://agentmods.dev/skills/marduk191/qwen3_mcp/constant-time-testing"><img src="https://agentmods.dev/badge/skills/marduk191/qwen3_mcp/constant-time-testing/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.
<a href="https://agentmods.dev/skills/marduk191/qwen3_mcp/constant-time-testing"><img src="https://agentmods.dev/badge/skills/marduk191/qwen3_mcp/constant-time-testing.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00025 | $0.04752 |
| Opus 5 | $0.00013 | $0.02376 |
| Sonnet 5 | $0.00005 | $0.00950 |
| Haiku 4.5 | $0.00003 | $0.00475 |
Grade B, and why
constant-time-testing scanned grade B with 1 finding 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.
Harvests environment variablesmediumData exfiltration
Enumerating or grepping the environment for keys collects credentials unrelated to what the mod says it does.
Timing attacks exploit variations in execution time to extract secret information from cryptographic implementations. Unlike cryptanalysis that targets theoretical weaknesses, timing attacks leverage implementation flaws Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.
This is a copy
97% identical to constant-time-testing — 5 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 508 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Constant-Time Testing
Timing attacks exploit variations in execution time to extract secret information from cryptographic implementations. Unlike cryptanalysis that targets theoretical weaknesses, timing attacks leverage implementation flaws - and they can affect any cryptographic code.
Background
Timing attacks were introduced by Kocher in 1996. Since then, researchers have demonstrated practical attacks on RSA (Schindler), OpenSSL (Brumley and Boneh), AES implementations, and even post-quantum algorithms like Kyber.
Key Concepts
| Concept | Description |
|---|---|
| Constant-time | Code path and memory accesses independent of secret data |
| Timing leakage | Observable execution time differences correlated with secrets |
| Side channel | Information extracted from implementation rather than algorithm |
| Microarchitecture | CPU-level timing differences (cache, division, shifts) |
Why This Matters
Timing vulnerabilities can:
- Expose private keys - Extract secret exponents in RSA/ECDH
- Enable remote attacks - Network-observable timing differences
- Bypass cryptographic security - Undermine theoretical guarantees
- Persist silently - Often undetected without specialized analysis
Two prerequisites enable exploitation:
- Access to oracle - Sufficient queries to the vulnerable implementation
- Timing dependency - Correlation between execution time and secret data
Common Constant-Time Violation Patterns
Four patterns account for most timing vulnerabilities:
// 1. Conditional jumps - most severe timing differences
if(secret == 1) { ... }
while(secret > 0) { ... }
// 2. Array access - cache-timing attacks
lookup_table[secret];
// 3. Integer division (processor dependent)
data = secret / m;
// 4. Shift operation (processor dependent)
data = a << secret;
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.
- 10d ago First seen · 508 lines · 25 tokens per session scan B ddf883f5659a
constant-time-testing is a skill published in the GitHub repository marduk191/qwen3_mcp (13 stars, last pushed 7mo ago), licensed MIT. It adds 25 tokens to every session and 4,752 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it B with 1 finding (harvests environment variables). It is 97% identical to constant-time-testing, differing in 5 lines, and is treated as a copy.
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