{
    "$schema": "http://json-schema.org/draft-04/schema#",
    "type": "array",
    "items": {
        "type": "object",
        "properties": {
            "shared_secret": {
                "type": "string"
            },
            "header": {
                "type": "string",
                "pattern": "^[a-zA-Z0-9]([a-zA-Z0-9-]+[a-zA-Z0-9])?$"
            },
            "algorithm": {
                    "enum": [
                        "hmac-md5",
                        "hmac-sha1",
                        "hmac-sha256",
                        "hmac-sha384",
                        "hmac-sha512"
                    ]
            }
        },
        "additionalProperties": false,
        "required": [
            "shared_secret",
            "header",
            "algorithm"
        ]
    }
}