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Configure a KMS

Learn how to configure a Key management service (KMS) to provide the keys used by Piiano Vault when it encrypts data​

Vault relies on a master key to generate encryption keys for property encryption, decryption, data signing, and verification. Use the Amazon Web Services (AWS), Google Cloud Platform (GCP) KMS, or Azure Key Vault to ensure secure property encryption when implementing Vault in a cloud environment. However, if you prefer to manage the keys independently or do not want to rely on a cloud provider, you can provide a seed for generating a secure master key.

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AWS KMS and GCP Cloud Key Management use a Hardware Security Module (HSM) to increase your key's security and to comply with PCI HSM requirements. Azure Key Vault uses HSM if you select the premium tier.

All instances of a Vault system should use the same KMS configuration, as they all work on the same database and rely on having identical keys. When using multiple Vaults, use separate KMS and avoid sharing KMS keys between systems.

To configure a cloud provider KMS, set the PVAULT_KMS_URI environment variable to the KMS key URI using these patterns:

KMSKMS identifier prefixKey URI format
AWS KMSaws-kms://aws-kms://arn:aws:kms:<region>:<account-id>:key/<key-id>
GCP KMSgcp-kms://gcp-kms://projects/*/locations/*/keyRings/*/cryptoKeys/*
Azure Key Vaultaz-kms://az-kms://<vault-base-url>/keys/<key-name>/<key-version>

Vault must have these permissions to be able to use the KMS:

  • Sign keys with the KMS
  • Verify keys with the KMS
  • Get the KMS public key

These high-level permissions have equivalent policies in AWS and GCP that must be granted to the AWS or GCP authenticated identity where Vault is running.

AWS​

For Vault to use AWS KMS, the following IAM policy is required (change the Resource field to the ARN of your CMK or alias):

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Action": [
                "kms:Encrypt",
                "kms:Decrypt"
            ],
            "Effect": "Allow",
            "Resource": "arn:aws:kms:us-west-2:111122223333:key/1234abcd-12ab-34cd-56ef-1234567890ab"
        }
    ]
}

Follow the principle of least privilege and limit access to kms:Encrypt and kms:Decrypt actions on the CMK to only the Vault instances to keep the encrypted data secure. Don't grant this policy to any other principals.

GCP​

For Vault to use GCP KMS, grant the roles/cloudkms.cryptoKeyEncrypterDecrypter role to the service account running Vault.

Follow the principle of least privilege and limit access to this role only to the Vault instances to keep the encrypted data secure. Don't grant this role to any other principals.

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The Vault roadmap includes support for controlling rotation parameters, complex queries over encrypted data, bring-your-own-key (BYOK) for multi-tenant applications, and more.

Azure​

For Vault to use Azure Key Vault, grant the Microsoft.KeyVault/vaults/keys/wrap/action and Microsoft.KeyVault/vaults/keys/unwrap/action Data Actions to your managed identity. For ease of use, you can assign the Key Vault Crypto Service Encryption User role to your managed identity.

Local (Seed)​

To use a local KMS, leave the environment variable PVAULT_KMS_URI empty and set the PVAULT_KMS_SEED to a random string. This seed is used to generate a master key for encryption purposes. The seed is not stored anywhere and is only used to generate the keys. Starting Vault with the same seed generates the same keys, so using a strong seed and treating it as a secret is important. Use at least a 256-bit, high-entropy random string.

When the environment variable PVAULT_DEVMODE is false (default), Vault does not start without a KMS URI. This is to prevent someone from starting Vault accidentally in production without a KMS. To start Vault in a production-ready state without the use of a cloud-based KMS, set PVAULT_KMS_ALLOW_LOCAL to true.

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When Vault starts without an external KMS or seed, it uses a built-in hard-coded master encryption key. This is convenient for development and testing purposes but is insecure and must not be used in a production environment that requires property encryption.

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