func algorithmFromPublicKey()

in pkg/cmd/jwks/root.go [155:178]

• 21 lines of code
• 7 McCabe index (conditional complexity)

func algorithmFromPublicKey(publicKey crypto.PublicKey) (jose.SignatureAlgorithm, error) {
	switch pk := publicKey.(type) {
	case *rsa.PublicKey:
		// IMPORTANT: If this function is updated to support additional key sizes,
		// signerFromRSAPrivateKey in serviceaccount/jwt.go must also be
		// updated to support the same key sizes. Today we only support RS256.
		return jose.RS256, nil
	case *ecdsa.PublicKey:
		switch pk.Curve {
		case elliptic.P256():
			return jose.ES256, nil
		case elliptic.P384():
			return jose.ES384, nil
		case elliptic.P521():
			return jose.ES512, nil
		default:
			return "", errors.New("unknown private key curve, must be 256, 384, or 521")
		}
	case jose.OpaqueSigner:
		return jose.SignatureAlgorithm(pk.Public().Algorithm), nil
	default:
		return "", errors.New("unknown public key type, must be *rsa.PublicKey, *ecdsa.PublicKey, or jose.OpaqueSigner")
	}
}