枚举 KeyChange 

pub enum KeyChange {
    Handshake {
        keys: Keys,
    },
    OneRtt {
        keys: Keys,
        next: Secrets,
    },
}

Key material 用于 use in QUIC packet spaces

QUIC uses 4 different sets of keys (并 progressive key updates 用于 long-running connections):

• Initial: these can be created from Keys::initial()
• 0-RTT keys: can be retrieved from ConnectionCommon::zero_rtt_keys()
• Handshake: these are returned from ConnectionCommon::write_hs() after ClientHello and ServerHello messages have been exchanged
• 1-RTT keys: these are returned from ConnectionCommon::write_hs() after the handshake is done

Once the 1-RTT keys have been exchanged, either side may initiate 一个 key update. Progressive update keys can be obtained 从 the Secrets returned in KeyChange::OneRtt。 Note that only packet keys are updated by key updates; header protection keys remain the same.

变体

Handshake

Keys 用于 the handshake space

字段

keys: Keys

Header 并 packet keys 用于 the handshake space

OneRtt

Keys 用于 1-RTT data

字段

keys: Keys

Header 并 packet keys 用于 1-RTT data

next: Secrets

Secrets 到 derive updated keys 从