验证文件时由未知实体做出的签名

如何解决验证文件时由未知实体做出的签名

我正在尝试验证我的文件是否运行此功能：

func VerifyGPGSig(target,signature,signingKey string) error {
    keyRingReader,err := os.Open(signingKey)
    if err != nil {
        return fmt.Errorf("Failed to open %s: %v",signingKey,err)
    }

    sig,err := os.Open(signature)
    if err != nil {
        return fmt.Errorf("Failed to open %s: %v",err)
    }

    t,err := os.Open(target)
    if err != nil {
        return fmt.Errorf("Failed to open %s: %v",target,err)
    }

    keyring,err := openpgp.ReadArmoredKeyRing(keyRingReader)
    if err != nil {
        return fmt.Errorf("Failed to read signing key: %v",err)
    }

    _,err = openpgp.CheckArmoredDetachedSignature(keyring,t,sig)
    if err != nil && err == io.EOF {
        // When the signature is binary instead of armored,the error is io.EOF.
        // Let's try with binary signatures as well
        _,err := openpgp.CheckDetachedSignature(keyring,sig)
        if err != nil && err == io.EOF {
            return fmt.Errorf("Failed to find valid signatures in the signature file: %v",err)
        }

        return fmt.Errorf("Failed to check signature: %v",err)
    }

    if err != nil {
        return fmt.Errorf("Failed to check signature: %v",err)
    }

    return nil
}

此功能的问题是我得到了错误：

Failed to check signature: openpgp: signature made by unkNown entity

从这里https://www.flatcar-linux.org/security/image-signing-key/Flatcar_Image_Signing_Key.asc

下载了GPG密钥

我没有找到要添加到公钥PGP密钥的任何基元。