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 vinayaklatthe/microsoft-security-skills --skill purview-customer-keygit clone --depth 1 https://github.com/vinayaklatthe/microsoft-security-skillsWrote 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/vinayaklatthe/microsoft-security-skills/purview-customer-key)<a href="https://agentmods.dev/skills/vinayaklatthe/microsoft-security-skills/purview-customer-key"><img src="https://agentmods.dev/badge/skills/vinayaklatthe/microsoft-security-skills/purview-customer-key/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/vinayaklatthe/microsoft-security-skills/purview-customer-key"><img src="https://agentmods.dev/badge/skills/vinayaklatthe/microsoft-security-skills/purview-customer-key.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 | $0.00235 | $0.02235 |
| Opus 5.5 | $0.00094 | $0.00894 |
| Sonnet 5.5 | $0.00047 | $0.00447 |
| Haiku 4.5 | $0.00023 | $0.00224 |
Grade A, and why
purview-customer-key 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 1mo 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 — 169 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Microsoft Purview Customer Key & Double Key Encryption
Microsoft already encrypts M365 data at rest with Microsoft-managed keys. These additional controls let regulated or sovereignty-sensitive customers hold the keys themselves:
- Customer Key — customer-supplied root keys (in Azure Key Vault HSM) wrap service data-encryption keys for Exchange, SharePoint, OneDrive, Teams (chats/files), and Purview. Revoke the key → Microsoft can no longer decrypt → service-data path crypto- shredded.
- Double Key Encryption (DKE) — sensitivity-label-driven client-side encryption where one key is customer-held in a self-hosted key release service. Microsoft never sees that key; service-side features (search, eDiscovery, Copilot) cannot read the content.
This skill covers both — when to use which, the architectures, and the operational realities.
When to use
- Regulatory mandate to hold encryption keys (financial sector sovereignty, defense, certain EU public sector).
- Crypto-shredding requirement (provable destruction by key revocation).
- The highest-sensitivity documents that must not be readable by Microsoft or by any service-side process even temporarily.
Do not use this skill for Azure resource encryption (azure-key-vault), generic
sensitivity-label rollout (purview-information-governance), or GRC frameworks
(compliance-manager).
Customer Key vs DKE — pick consciously
| Feature | Customer Key | DKE |
|---|---|---|
| Scope | All data in selected M365 services | Per-document, label-driven |
| Encryption point | Service-side, transparent | Client-side, before upload |
| Microsoft can read for service features? | Yes (until key revoked) | No |
| eDiscovery, Search, Copilot, DLP work on content? | Yes | No |
| Key custody | Azure Key Vault HSM (customer subscription) | Customer-hosted key release service (on-prem or your cloud) |
| Crypto-shred via revocation? | Yes (service-wide) | Per-document by destroying key |
| Use case | Sovereignty, blanket regulator demand | Crown-jewel docs only |
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.
- 1mo ago First seen · 169 lines · 235 tokens per session scan A 76b01b628bbe
purview-customer-key is a skill published in the GitHub repository vinayaklatthe/microsoft-security-skills (178 stars, last pushed 4mo ago), licensed MIT. It adds 235 tokens to every session and 2,235 once invoked, about $0.0009 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 2026-09-03.
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