特性 Signer 

pub trait Signer:
    Debug
    + Send
    + Sync {
    // Required methods
    fn sign(&self, message: &[u8]) -> Result<Vec<u8>, Error>;
    fn scheme(&self) -> SignatureScheme;
}

A thing that can sign 一个 message.

必需方法

fn sign(&self, message: &[u8]) -> Result<Vec<u8>, Error>

Signs message using the selected scheme.

message is not hashed; the implementer must hash it using the hash function implicit in Self::scheme()。

此 returned signature format 也 defined by Self::scheme()。

fn scheme(&self) -> SignatureScheme

Reveals which scheme ， 用 when you call Self::sign()。

实现者