Condition keys for Nitro Enclaves and Nitro Sandboxes

The following condition keys are specific to Nitro Enclaves and Nitro Sandboxes attestation:

kms:RecipientAttestation:ImageSha384

The kms:RecipientAttestation:ImageSha384 condition key controls access to Decrypt, DeriveSharedSecret, GenerateDataKey, GenerateDataKeyPair, and GenerateRandom with a KMS key when the image digest from the signed attestation document in the request matches the value in the condition key. The ImageSha384 value corresponds to PCR0 in the attestation document. This condition key is effective only when the Recipient parameter in the request specifies a signed attestation document for an AWS Nitro Enclave or Nitro Sandbox.

This value is also included in CloudTrail events for requests to AWS KMS for Nitro Enclaves and Nitro Sandboxes.

For example, the following key policy statement allows the data-processing role to use the KMS key for Decrypt, DeriveSharedSecret, GenerateDataKey, GenerateDataKeyPair, and GenerateRandom operations. The kms:RecipientAttestation:ImageSha384 condition key allows the operations only when the image digest value (PCR0) of the attestation document in the request matches the image digest value in the condition. This condition key is effective only when the Recipient parameter in the request specifies a signed attestation document for an AWS Nitro Enclave or Nitro Sandbox.

If the request does not include a valid attestation document from an AWS Nitro Enclave or Nitro Sandbox, permission is denied because this condition is not satisfied.

{
  "Sid" : "Enable Enclave data processing",
  "Effect" : "Allow",
  "Principal" : {
    "AWS" : "arn:aws:iam::111122223333:role/data-processing"
  },
  "Action": [
    "kms:Decrypt",
    "kms:DeriveSharedSecret",
    "kms:GenerateDataKey",
    "kms:GenerateDataKeyPair",
    "kms:GenerateRandom"
  ],
  "Resource" : "*",
  "Condition": {
    "StringEqualsIgnoreCase": {
      "kms:RecipientAttestation:ImageSha384": "9fedcba8abcdef7abcdef6abcdef5abcdef4abcdef3abcdef2abcdef1abcdef1abcdef0abcdef1abcdef2abcdef3abcdef4abcdef5abcdef6abcdef7abcdef99"
    }
  }
}

kms:RecipientAttestation:PCR<PCR_ID>

The kms:RecipientAttestation:PCR<PCR_ID> condition key controls access to Decrypt, DeriveSharedSecret, GenerateDataKey, GenerateDataKeyPair, and GenerateRandom with a KMS key only when the platform configuration registers (PCRs) from the signed attestation document in the request match the PCRs in the condition key. This condition key is effective only when the Recipient parameter in the request specifies a signed attestation document from an AWS Nitro Enclave or Nitro Sandbox.

This value is also included in CloudTrail events that represent requests to AWS KMS for Nitro Enclaves and Nitro Sandboxes.

To specify a PCR value, use the following format. Concatenate the PCR ID to the condition key name. You can specify a PCR ID that identifies one of the six Enclave measurements or a custom PCR ID that you defined for a specific use case. The PCR value must be a lower-case hexadecimal string of up to 96 bytes.

"kms:RecipientAttestation:PCRPCR_ID": "PCR_value"

For example, the following condition key specifies a particular value for PCR1, which corresponds to the hash of the kernel used for the Enclave and the bootstrap process.

kms:RecipientAttestation:PCR1: "abc1abcdef2abcdef3abcdef4abcdef5abcdef6abcdef7abcdef8abcdef9abcdef8abcdef7abcdef6abcdef5abcdef4abcdef3abcdef2abcdef1abcdef0abcde"

The following example key policy statement allows the data-processing role to use the KMS key for the Decrypt operation.

The kms:RecipientAttestation:PCR condition key in this statement allows the operation only when the PCR1 value in the signed attestation document in the request matches kms:RecipientAttestation:PCR1 value in the condition. Use the StringEqualsIgnoreCase policy operator to require a case-insensitive comparison of the PCR values.

If the request does not include an attestation document, permission is denied because this condition is not satisfied.

{
  "Sid" : "Enable Enclave data processing",
  "Effect" : "Allow",
  "Principal" : {
    "AWS" : "arn:aws:iam::111122223333:role/data-processing"
  },
  "Action": "kms:Decrypt",
  "Resource" : "*",
  "Condition": {
    "StringEqualsIgnoreCase": {
      "kms:RecipientAttestation:PCR1": "abc1de4f2dcf774f6e3b679f62e5f120065b2e408dcea327bd1c9dddaea6664e7af7935581474844767453082c6f1586116376cede396a30a39a611b9aad7966c87"
    }
  }
}

kms:RecipientAttestation:PCR8:ServiceName

The kms:RecipientAttestation:PCR8:ServiceName condition key controls access to Decrypt, DeriveSharedSecret, GenerateDataKey, GenerateDataKeyPair, and GenerateRandom with a KMS key when the AWS service that signed the enclave image file (EIF) in the signed attestation document matches the service name in the condition key.

PCR8 of the attestation document records the hash of the EIF signing certificate. AWS KMS maintains a mapping of PCR8 values to AWS service names and populates this condition key with the matching service name. The possible values are:

This condition key is effective only when the Recipient parameter in the request specifies a signed attestation document from an AWS Nitro Enclave or Nitro Sandbox, and PCR8 in that attestation document matches a registered value. Otherwise, AWS KMS does not populate this condition key.

When the EIF is signed by an AWS service, use this condition key instead of kms:RecipientAttestation:PCR8 to avoid breakage when the service rotates its signing certificate.

This value is also included in CloudTrail events for requests to AWS KMS for Nitro Enclaves and Nitro Sandboxes.

For example, the following key policy statement allows the data-processing role to use the KMS key for the Decrypt operation. The kms:RecipientAttestation:PCR8:ServiceName condition key allows the operation only when the EIF signing certificate in the attestation document is registered to Amazon ECS. Use the StringEquals policy operator for an exact match on the service name. If the request does not include a valid attestation document from an AWS Nitro Enclave or Nitro Sandbox, or if PCR8 is not registered to the specified service name, permission is denied because this condition is not satisfied.

{
  "Sid" : "Enable attested data processing for an Enclave signed by Amazon ECS",
  "Effect" : "Allow",
  "Principal" : {
    "AWS" : "arn:aws:iam::111122223333:role/data-processing"
  },
  "Action": "kms:Decrypt",
  "Resource" : "*",
  "Condition": {
    "StringEquals": {
      "kms:RecipientAttestation:PCR8:ServiceName": "ecs.amazonaws.com"
    }
  }
}