Go 验证文件时未知实体所做的签名

我正在尝试验证运行此函数的文件：

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", signature, 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, t, 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
}

此函数的问题是我得到了错误：

failed to check signature: openpgp: signature made by unknown entity

GPG密钥从此处下载

我还没有找到任何原语添加到密钥环的公共PGP密钥