之前做iOS使用的是AES+RSA加密，这次flutter使用sha1验签
php给的文档。php通过hash_hmac方法直接传入两个参数token和数据，token对数据字符串加密获得签名。
function signature(array $data, $token)
{
    $signStr = '';
    ksort($data);
    foreach ($data as $key=>$val){
        if(!is_scalar($val)){
            $val = json_encode($val);
        }
        $signStr .= $key . $val;
    }
    return strtoupper(bin2hex(hash_hmac('sha1', $signStr, $token, true)));
}

flutter中解决 解密出来的结果是103c6e83fa9c75a1f20486f950faaddafd9e3f65 跟php验签成功
    const token = "qmbn6jmgxidclbarne9srczb92yz53pe";
    Map parameters = {
      "auth_name": "qqqqqqq",
      "APP-ID": "123456",
    };
    //获得字典中所有key并排序
    List attrKeys = parameters.keys.toList();
    attrKeys.sort();
    
    //获得字典中数据的字符串
    String parameterStr = '';
    for (var i = 0; i < attrKeys.length; i++) {
      parameterStr += "${attrKeys[i]}${parameters[attrKeys[i]]}";
    }

    var key = utf8.encode(token);
    var bytes = utf8.encode(parameterStr);
    //使用token对字典加密
    var hmacSha1 = Hmac(sha1, key);
    Digest sha1Result = hmacSha1.convert(bytes);
    //转大写字符串
    var sha1ResultStr = sha1Result.toString().toUpperCase();
    print("sha1ResultStr:$sha1ResultStr");