azure-sdk-for-cpp/sdk/attestation/azure-security-attestation/samples/policy/README.md

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Policy Samples for the Microsoft Azure Attestation client library for C++

These code samples show how to set and reset attestation policies using the Attestation client library.

Sample Requirements

These samples are written with the assumption that the following environment variables have been set by the user:

• ATTESTATION_AAD_URL - the base URL for an attestation service instance in AAD mode.
• ATTESTATION_ISOLATED_URL - the base URL for an attestation service instance in Isolated mode.
• ISOLATED_SIGNING_KEY - a Base64 encoded ASN.1 DER representation of a private key used when creating the ATTESTATION_ISOLATED_URL instance.
• ISOLATED_SIGNING_CERTIFICATE - a Base64 encoded DER X.509 certificate wrapping the public key of the ISOLATED_SIGNING_KEY.

Samples descriptions

The samples are structured as separate source files, one per scenario. The are:

Sample	What it tests	Notes
Get_Policy	Retrieves the attestation policy for a specific attestation instance.
Set_Policy	Sets an attestation policy on an AAD attestation instance.	Note: The policy being set in this sample is unsigned.
Set_Sealed_Policy	Sets an attestation policy on an isolated attestation instance	Note: This sample requires the ISOLATED_ environment variables.
Reset_Policy	Resets the attestation policy for an AAD instance to the default value for the attestation type.
Reset_Sealed_Policy	Resets an attestation policy to the default value on an isolated attestation instance	Note: This sample requires the ISOLATED_ environment variables.

Additional Information

Attestation Policy

An attestation policy is a document which defines authorization and claim generation rules for attestation operations.

The following is an example of an attestation policy document for an SGX enclave:

version= 1.0;
authorizationrules
{
    [ type=="x-ms-sgx-is-debuggable", value==false ] &&
    [ type=="x-ms-sgx-product-id", value==<product-id> ] &&
    [ type=="x-ms-sgx-svn", value>= 0 ] &&
    [ type=="x-ms-sgx-mrsigner", value=="<mrsigner>"]
        => permit();
};
issuancerules {
    c:[type=="x-ms-sgx-mrsigner"] => issue(type="<custom-name>", value=c.value);
};

There are two sections to the document: authorizationrules and issuancerules. authorizationrules are rules which control whether an attestation token should be issued. issuancerules are rules which cause claims to be issued in an attestation token.

In the example, the attestation service will issue an attestation token if and only if the SGX enclave is configured as follows:

• Not-Debuggable
• Enclave product ID: <product-id>.
• Enclave SVN: <svn value> greater or equal to zero.
• Enclave signer: matches <mrsigner>.

Assuming a token is issued, this policy will cause a claim named <custom-name> to be issued with a value which matches the x-ms-sgx-mrsigner claim.

For more information on authoring attestation policy documents, see: Authoring an attestation policy

Next Steps

For more information about the Microsoft Azure Attestation service, please see our documentation page .