What is cryptographic-signing?

A guide for a local Go package that signs approved access claims with an RSA private key using the PS256 algorithm. It also describes how hosts supply the signer and verify its public keys.

Use it to maintain the RSA-PSS signer, connect it to the token refresh manager, publish its public key information, and keep verification strict.

It clarifies the boundary between signing and authentication, so importing the package is not mistaken for granting access or replacing other token-signing paths.

How greenpau/go-authcrunch configures Codex

Reuse

Borrowing it

Nothing to install: this file belongs to greenpau/go-authcrunch. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/greenpau/go-authcrunch/main/.codex/skills/cryptographic-signing/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/greenpau/go-authcrunch

Made for: Codex.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/greenpau/go-authcrunch/cryptographic-signing/github.svg)](https://agentmods.dev/skills/greenpau/go-authcrunch/cryptographic-signing)

Your own site

<a href="https://agentmods.dev/skills/greenpau/go-authcrunch/cryptographic-signing"><img src="https://agentmods.dev/badge/skills/greenpau/go-authcrunch/cryptographic-signing/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/greenpau/go-authcrunch/cryptographic-signing"><img src="https://agentmods.dev/badge/skills/greenpau/go-authcrunch/cryptographic-signing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 50 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 2,496 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.

Model	Per session	Once invoked
Fable 5.1	$0.00050	$0.02496
Opus 5.5	$0.00020	$0.00998
Sonnet 5.5	$0.00010	$0.00499
Haiku 4.5	$0.00005	$0.00250

Measured 12d ago against content hash 1376e58daaaf, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

cryptographic-signing 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 12d 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.

.codex/skills/cryptographic-signing/SKILL.md · 201 lines

How it starts

The opening of the file, as written. The whole thing — 201 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Cryptographic Signing

Ownership and integration

The working reference is plugins/cryptographic-signing/rsapss. It signs approved access claims with a local RSA private key. It implements tokenrefresh.Signer and is supplied to tokenrefresh.NewManager. The embedding host owns authentication, identity revalidation, session storage, HTTP transport, and publication of verification keys. A successful signature alone does not authorize issuance or commit a session.

This is an ordinary Go package in the root module. It has no registration side effects, workers, remote services, key generation, or nested module. Core production code must not import it. Hosts declare core-owned external signer metadata and supply borrowed runtime handles through ServerOptions.AccessSigners; portals select the name with an explicit matching access-token profile. Native configuration alone does not construct an external backend. Standalone portals can receive the same typed binding. Read selected access signing for root/portal assembly, approved claims, consumer profiles, discovery and persistent trust. OP ID signing remains separate; importing a plugin does not change that owner.

pkg/kms/rsa_pss.go supplies the core verification integration. Existing RSA public-key configuration can verify PS256 tokens from this plugin. An explicit core access profile additionally enforces purpose, issuer, sole audience and temporal limits across the complete consumer, with no fallback to unrelated keys. Ordinary RSA issuance retains its RS methods and defaults. Neither surface enables PS384 or PS512.

Public configuration and parser

rsapss.Config has key_file, key_id, algorithm, issuer, audience, and max_lifetime fields. Validate normalizes defaults and validates without file I/O. rsapss.New(*Config) validates its own copy and loads the key before publishing a signer. A failed constructor returns no runtime object.

Read the full file on GitHub · 201 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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.

12d ago Changed · +28 lines · +2 tokens per session 1376e58daaaf
29d ago First seen · 173 lines · 48 tokens per session scan A f14f089cf4e0

Subscribe to this mod's changes

cryptographic-signing is a skill published in the GitHub repository greenpau/go-authcrunch (60 stars, last pushed 10d ago), licensed Apache-2.0. It adds 50 tokens to every session and 2,496 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-10-08.