Keystore file format for Kukai and other wallets

Question

When a new HD wallet is created in Kukai and Temple, the following keystore JSON file is generated:

{
    "provider": "Kukai",
    "version": 3,
    "walletType": 4,
    "encryptedSeed": "2461...==0671...",
    "encryptedEntropy": "8c41...",
    "iv": "0a61..."
}

Is there a specification of this keystore format?