函数 verify_tls13_signature 

pub fn verify_tls13_signature(
    msg: &[u8],
    cert: &CertificateDer<'_>,
    dss: &DigitallySignedStruct,
    supported_schemes: &WebPkiSupportedAlgorithms,
) -> Result<HandshakeSignatureValid, Error>

验证 一个 message signature using the cert 公钥 并 the first TLS 1.3 compatible supported scheme.

This function verifies the dss signature over message using the subject 公钥 从 cert。 Unlike verify_tls12_signature, 此函数 only tries the first matching scheme. See WebPkiSupportedAlgorithms::mapping 以获取更多信息。