Azure Confidential Ledger: Fix Common Issues & Setup Errors

Before Azure Confidential Ledger can authenticate your application, you need a registered app in Microsoft Entra ID (formerly Azure Active Directory). If you already have one, skip to grabbing the object ID. If not, here's the exact path through the portal.

Go to Microsoft Entra ID → App registrations → New registration. Give it a name that reflects the app or service that will be accessing the ledger, something specific, not "test-app." Under Supported account types, select the option appropriate for your organization (usually "Accounts in this organizational directory only"). Leave the redirect URI blank for a backend service. Click Register.

Once it's created, copy down two values from the overview page: the Application (client) ID and the Object ID. You need the Object ID specifically when you add this app as a user inside the ledger.

Now create a client secret so your app can authenticate. Go to Certificates & secrets → New client secret. Set an expiration that aligns with your rotation policy, I typically recommend 12 months maximum and storing it immediately in Azure Key Vault. Copy the secret value right now because Azure only shows it once.

To get an access token for the ledger, your app needs to request the https://confidential-ledger.azure.com/.default scope. Make sure your token request is targeting this scope exactly, using a generic Azure scope won't work and will give you an access token that the ledger rejects with a 401.

Once you have a valid token, you'll see successful authentication against the ledger's management endpoint. If the token request itself is failing, check that the app registration is in the same tenant as your ledger subscription.

This is the step that trips up almost everyone who has Azure experience but is new to Azure Confidential Ledger. You've registered the app in Entra ID, but the ledger has no idea who that app is yet. You have to explicitly add it as a user through the ledger's own data plane API.

This requires being an existing Administrator-level user on the ledger. If you just created the ledger, you already have that role. Get a valid Entra ID access token first (using the scope from Step 1), then call the user management endpoint:

PUT https://<ledger-name>.confidential-ledger.azure.com/app/users/<aad-object-id>
Content-Type: application/json
Authorization: Bearer <your-admin-token>

{
  "assignedRole": "Contributor"
}

The assignedRole field accepts three values: Administrator, Contributor, or Reader. Use Contributor for applications that need to write data. Use Reader for audit or read-only access. Only assign Administrator when the identity needs to manage other users or configure the ledger itself.

Replace <aad-object-id> with the Object ID you copied from the app registration overview page, not the Application (client) ID. This is a common mix-up. The object ID is the internal identifier Microsoft Entra ID uses for the principal; the client ID is used for token acquisition.

After the PUT call returns a 200, your app can authenticate against the ledger using its Entra ID token and will have the rights corresponding to its assigned role. Confirm by making a GET call to /app/users/<aad-object-id> and verifying the response shows the correct assigned role.

Some scenarios, air-gapped environments, IoT edge devices, or legacy systems, can't easily use OAuth 2.0 token flows. Azure Confidential Ledger supports certificate-based authentication as a genuine alternative, not a fallback. It works well when set up correctly.

Start by creating a client certificate. You need a PEM-encoded certificate. For development and testing, you can generate one with OpenSSL:

openssl req -newkey rsa:2048 -new -nodes -x509 -days 365 \
  -keyout client_private_key.pem \
  -out client_cert.pem \
  -subj "/CN=my-acl-client"

For production, use a certificate issued by your organization's PKI or a trusted certificate authority, don't use self-signed certificates in production environments. Once you have the certificate, you register it with the ledger using the same user management endpoint as Step 2, but the request body changes slightly to reference the certificate's PEM data rather than an Entra object ID.

Upload the certificate via an API call authenticated with your existing admin credentials. The ledger stores the certificate fingerprint internally. When your client connects, it presents the certificate as part of the TLS 1.3 mutual authentication handshake, the ledger validates the fingerprint against its stored records.

One important detail: each certificate-based user also gets an assignedRole the same way Entra ID users do. If a certificate-authenticated client is getting 403 errors even though authentication is succeeding, the role assignment is the problem, check it with a GET call to the user endpoint using the certificate's thumbprint as the identifier.

You'll know certificate auth is working when your SDK or HTTP client connects without a 401 and can perform operations consistent with the assigned role. The Python and .NET SDKs both have built-in support for presenting client certificates, check the SDK initialization docs for the exact constructor parameter.

Once authentication is sorted, the next common failure point is data operations themselves. If your application can authenticate but writes are failing or data retrieval returns unexpected empty results, collection ID configuration is usually the culprit.

Azure Confidential Ledger supports grouping data using collection IDs, which is a way to logically segment your data within a single ledger instance. Think of them as namespaces. If you write data to one collection ID and then query without specifying the same collection ID, or vice versa, you'll get results that look wrong even though the data is there.

When writing a transaction, specify the collection ID explicitly in your request:

POST https://<ledger-name>.confidential-ledger.azure.com/app/transactions?collectionId=production-logs
Content-Type: application/json
Authorization: Bearer <token>

{
  "contents": "your-payload-here"
}

If you omit collectionId, Azure Confidential Ledger writes to a default collection. The problem is when some writes specify a collection ID and others don't, you end up with data scattered across the default collection and named collections, making queries return incomplete results.

For read operations, always specify the same collection ID you used during write. The transaction ID returned by a successful write is scoped to that collection. Using that transaction ID against a different collection ID in a GET request will return a 404 even though the transaction exists, it just lives in a different collection.

Also check your ledger type. Azure Confidential Ledger supports two types at creation: public (data stored in plain text) and private (data stored encrypted). You cannot change this after creation. If you're seeing data come back encrypted when you expected plain text, your ledger was created as private type. You'll need to provision a new ledger with the correct type if this doesn't match your requirements.

One of the most powerful features of Azure Confidential Ledger, and one of the least understood, is the transaction receipt system. Every single write transaction generates a receipt containing Merkle tree data that you can use to cryptographically verify the transaction's integrity at any point in the future. If you're not capturing and verifying receipts, you're leaving the core value proposition of the service on the table.

After a successful write, call the receipt endpoint to retrieve it:

GET https://<ledger-name>.confidential-ledger.azure.com/app/transactions/<transactionId>/receipt
Authorization: Bearer <token>

The response contains the Merkle proof, a set of hashes that trace a path from your specific transaction up to the root hash of the blockchain state at that point. Store this receipt alongside your data or in a separate audit system. Without it, you can't independently verify your data hasn't been tampered with.

To verify a receipt later, you also need to establish trust in the ledger itself using the service identity endpoint. This gives you the ledger's TLS certificate, which you can validate against Microsoft's published certificate chain. The trust establishment process confirms that the endpoint you're talking to is actually running inside a genuine Intel SGX enclave, not a spoofed endpoint:

GET https://<ledger-name>.confidential-ledger.azure.com/app/enclaveQuotes

This returns attestation quotes from each ledger node (the service runs across three or more identical instances for high availability). If receipt verification is failing, the most common cause is using a stale or cached service certificate rather than fetching the current one at the time of verification. Always re-fetch the service identity when setting up a new verification run.

If you're using the Python or .NET SDK, the verification utilities are built in, you don't need to implement the Merkle proof checking yourself. The SDK's verify_receipt method handles the full cryptographic chain. A successful verification returns True with no exception. Any verification failure throws an exception with a message indicating which part of the chain broke, that's your signal to escalate and investigate whether data has been tampered with.