Struct SignReceiptOptions 

pub struct SignReceiptOptions<'a> {
    pub receipt_id: &'a str,
    pub timestamp: &'a str,
    pub field_path: &'a str,
    pub action: &'a str,
    pub service_name: &'a str,
    pub key: Option<&'a [u8]>,
}

The inputs to sign_receipt a caller pins rather than generates. Every identity-bearing field is a parameter so the fixture vectors can be reproduced exactly.

Fields

receipt_id: &'a str

timestamp: &'a str

field_path: &'a str

action: &'a str

service_name: &'a str

key: Option<&'a [u8]>

Signing key. None leaves hmac empty — an unsigned receipt.