Function unsupportedCertificateError

auth.go:253–289

unsupportedCertificateError returns a helpful error for certificates with an unsupported private key.

(cert *Certificate)

// unsupportedCertificateError returns a helpful error for certificates with
// an unsupported private key.
func unsupportedCertificateError(cert *Certificate) error {
	switch cert.PrivateKey.(type) {
	case rsa.PrivateKey, ecdsa.PrivateKey:
		return fmt.Errorf("tls: unsupported certificate: private key is %T, expected *%T",
			cert.PrivateKey, cert.PrivateKey)
	case *ed25519.PrivateKey:
		return fmt.Errorf("tls: unsupported certificate: private key is *ed25519.PrivateKey, expected ed25519.PrivateKey")
	}

	signer, ok := cert.PrivateKey.(crypto.Signer)
	if !ok {
		return fmt.Errorf("tls: certificate private key (%T) does not implement crypto.Signer",
			cert.PrivateKey)
	}

	switch pub := signer.Public().(type) {
	case *ecdsa.PublicKey:
		switch pub.Curve {
		case elliptic.P256():
		case elliptic.P384():
		case elliptic.P521():
		default:
			return fmt.Errorf("tls: unsupported certificate curve (%s)", pub.Curve.Params().Name)
		}
	case *rsa.PublicKey:
		return fmt.Errorf("tls: certificate RSA key size too small for supported signature algorithms")
	case ed25519.PublicKey:
	default:
		return fmt.Errorf("tls: unsupported certificate key (%T)", pub)
	}

	if cert.SupportedSignatureAlgorithms != nil {
		return fmt.Errorf("tls: peer doesn't support the certificate custom signature algorithms")
	}

	return fmt.Errorf("tls: internal error: unsupported key (%T)", cert.PrivateKey)
}