Joseph Doherty
68 lines
3.3 KiB
Markdown
68 lines
3.3 KiB
Markdown
# ZB.MOM.WW.Secrets
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A reusable, envelope-encrypted **secrets manager** for the `ZB.MOM.WW.*` SCADA family:
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store secrets (SQL passwords, API tokens, connection strings) encrypted at rest and get the
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plaintext back on demand — from application code, from configuration, or from an operator UI.
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## Packages
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| Package | Purpose |
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| `ZB.MOM.WW.Secrets.Abstractions` | Contracts only (`ISecretStore`, `ISecretResolver`, `IMasterKeyProvider`, `ISecretCipher`, `ISecretReplicator`, `ISecretCacheInvalidator`, `ISecretActorAccessor`), value types, exceptions. Dependency-light. |
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| `ZB.MOM.WW.Secrets` | Implementation: AES-256-GCM envelope cipher, env/file/DPAPI master-key providers, SQLite store, TTL resolver (audited), `${secret:}` config expander, `AddZbSecrets`. |
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| `ZB.MOM.WW.Secrets.Ui` | Blazor RCL on `ZB.MOM.WW.Theme`: list / add / rotate / delete + policy-gated, audited reveal. |
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A `secret` CLI (`set` / `get` / `list` / `rm` / `rotate`) ships in the repo (not packed).
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## How it protects secrets
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Each value is encrypted with a fresh **data key (DEK)** using AES-256-GCM; the DEK is then
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**wrapped** by a **master KEK** that never touches the database. The AAD binds the ciphertext
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to the secret's name and the wrapped DEK to the KEK id, so rows can't be swapped and a
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tampered/mis-keyed row **fails closed** (`SecretDecryptionException`) rather than returning a
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wrong value. The master KEK is resolved through a pluggable `IMasterKeyProvider`
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(environment variable, key file, or Windows DPAPI).
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## Wiring it up
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```csharp
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builder.Services.AddZbSecrets(builder.Configuration, "Secrets");
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// After config load, BEFORE options validation — expand ${secret:...} references:
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var expander = new SecretReferenceExpander(app.Services.GetRequiredService<ISecretResolver>());
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await expander.ExpandConfigurationAsync((IConfigurationRoot)builder.Configuration, ct);
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```
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```jsonc
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// appsettings.json
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"Secrets": {
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"SqlitePath": "secrets.db",
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"MasterKey": { "Source": "Environment", "EnvVarName": "ZB_SECRETS_MASTER_KEY" },
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"RunMigrationsOnStartup": true,
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"ResolveCacheTtl": "00:00:30"
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},
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// Keep plaintext out of config — reference a stored secret instead:
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"ConnectionStrings": {
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"Historian": "Server=...;User Id=sa;Password=${secret:sql/historian-password}"
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}
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```
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The master key is 32 bytes, provided base64 in `ZB_SECRETS_MASTER_KEY` (Environment source).
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A missing/invalid key fails closed at startup (`MasterKeyUnavailableException`).
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## Runtime + human access
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- **App code:** inject `ISecretResolver` and call `GetAsync(name, ct)`. Every resolve is
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audited via `ZB.MOM.WW.Audit` (name + outcome only — the value is never logged).
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- **Operators:** mount the `ZB.MOM.WW.Secrets.Ui` `/admin/secrets` page. The list shows
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**metadata only**; revealing a value requires the `secrets:reveal` authorization policy and
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is audited. Add/rotate/delete require `secrets:manage`.
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## Clustered deployments
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Secrets storage is local SQLite by default. The schema already carries the
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`revision` / `updated_utc` / tombstone columns and an `ISecretReplicator` seam for
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cluster replication, but the Akka replicator (`ZB.MOM.WW.Secrets.Akka`) is a deferred
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follow-on. **When replicating across a node pair, every node must resolve the _same_ master
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KEK** (e.g. the same mounted key file) — a row wrapped by an unknown KEK fails closed.
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