singpass-legacy

singpass-legacy is a skill for Claude Code from kyleoliveiro/sg-gov-skills. It costs 210 tokens per session (2,820 once invoked), scanned A, original, MIT.

A maintenance guide for older Singpass integrations, including Myinfo versions 3 and 4 and the earlier authentication API. Singpass is Singapore's national digital identity service, while Myinfo lets approved services retrieve verified user information.

In plain words
What is it for?
Use it to identify the legacy Singpass interface in a project, maintain or debug it, or migrate it toward the newer integration before the stated end-of-September 2026 deadline.
Why use it?
These integrations use different endpoints, authentication methods, signing, encryption, and token details. Treating them as interchangeable can break an existing service or create security and migration problems.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the national-digital-identity plugin — 4 skills shipped together

Good fit Use it to identify the legacy Singpass interface in a project, maintain or debug it, or migrate it toward the newer integration before the stated end-of-September 2026 deadline.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/kyleoliveiro/sg-gov-skills/singpass-legacy
Install

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.

Any agent
npx skills add kyleoliveiro/sg-gov-skills --skill singpass-legacy
Clone the repo
git clone --depth 1 https://github.com/kyleoliveiro/sg-gov-skills

Made for: Claude Code.

Or install national-digital-identity, the plugin that ships this one along with the rest of its 4 skills.

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 singpass-legacy

README.md
[![agentmods](https://agentmods.dev/badge/skills/kyleoliveiro/sg-gov-skills/singpass-legacy/github.svg)](https://agentmods.dev/skills/kyleoliveiro/sg-gov-skills/singpass-legacy)
Your own site
<a href="https://agentmods.dev/skills/kyleoliveiro/sg-gov-skills/singpass-legacy"><img src="https://agentmods.dev/badge/skills/kyleoliveiro/sg-gov-skills/singpass-legacy/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 singpass-legacy

Your own site · 80×15
<a href="https://agentmods.dev/skills/kyleoliveiro/sg-gov-skills/singpass-legacy"><img src="https://agentmods.dev/badge/skills/kyleoliveiro/sg-gov-skills/singpass-legacy.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 210 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,820 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 $0.00210 $0.02820
Opus 5 $0.00105 $0.01410
Sonnet 5 $0.00042 $0.00564
Haiku 4.5 $0.00021 $0.00282

Measured 11d ago against content hash fdfc0da7df4b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

singpass-legacy 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 11d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (evals/files/myinfo-v3-client.js), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/singpass-legacy/SKILL.md · 166 lines

How it starts

The opening of the file, as written. The whole thing — 166 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Singpass legacy: Myinfo v3/v4 and the pre-FAPI authentication API

Three distinct legacy surfaces are still running in production across agencies. Identify which one you are looking at before touching anything:

Surface Endpoints Client auth Payload crypto
Myinfo v3 api.myinfo.gov.sg/com/v3/* (/authorise — British spelling) client_id + client_secret + Authorization: PKI_SIGN RS256 base-string signature keyed by an X.509 RSA cert JWE RSA-OAEP + A256GCM wrapping RS256 JWS
Myinfo v4 api.myinfo.gov.sg/com/v4/* (/authorize) ES256 client assertion (aud = the API URL, adds cnf.jkt) + DPoP; no secret, no X.509 JWE ECDH-ES+A256KW + A256GCM wrapping ES256 JWS
Pre-FAPI Singpass auth API id.singpass.gov.sg/auth, /token, /userinfo (no /fapi prefix, no PAR) private_key_jwt (aud = bare issuer URL), PKCE S256 ID token JWS, or JWS-in-JWE (ECDH-ES+A*KW + A256CBC-HS512) for PII clients

The JWE recipes differ across all three — decryption code is not portable, and neither are client assertions (aud differs per system).

Deadlines:

  • Myinfo v3/v4 → v5: end Sep 2026 (per the current Myinfo FAQ; the legacy v4 FAQ still shows a stale "30 Sept 2025" — the live current-docs date governs). v3/v4 onboarding is discontinued and the official connectors are frozen.
  • All Singpass apps FAPI 2.0-compliant by 31 Dec 2026 (banner on every pre-FAPI docs page).
  • The last Myinfo v3 X.509 verification certificate expired 7 Nov 2024 — still-running v3 services must have downloaded the renewed cert and toggled "Renewed certificate" in the SDP app details, or signature verification breaks.

For anything new, use the singpass skill. This skill's jobs: keep legacy integrations alive until migration, and execute the migration without the silent breakages.

Source and currency

Embedded from the legacy sections of https://docs.developer.singpass.gov.sg as of 2026-07-23 (append .md to page URLs for markdown). Full wire formats, error tables, and migration checklists: references/legacy-surfaces-and-migration.md. Caution: the "Technical Concepts" pages filed under the pre-FAPI docs tree are actually FAPI-era content (they reference PAR/DPoP and the /fapi audience) — don't treat them as pre-FAPI-normative.

Read the full file on GitHub · 166 lines

Files

What ships with it

5 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.

  1. 11d ago First seen · 166 lines · 210 tokens per session scan A fdfc0da7df4b

Subscribe to this mod's changes

singpass-legacy is a skill published in the GitHub repository kyleoliveiro/sg-gov-skills (16 stars, last pushed 1mo ago), licensed MIT. It adds 210 tokens to every session and 2,820 once invoked, about $0.0011 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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