Example 1: As a query string

queryString: symbol=LTCBTC&side=BUY&type=LIMIT&timeInForce=GTC&quantity=1&price=0.1&recvWindow=5000&timestamp=1499827319559

HMAC SHA256 signature:

[linux]$ echo -n "symbol=LTCBTC&side=BUY&type=LIMIT&timeInForce=GTC&quantity=1&price=0.1&recvWindow=5000&timestamp=1499827319559" | openssl dgst -sha256 -hmac "NhqPtmdSJYdKjVHjA7PZj4Mge3R5YNiP1e3UZjInClVN65XAbvqqM6A7H5fATj0j"
(stdin)= c8db56825ae71d6d79447849e617115f4a920fa2acdcab2b053c4b2838bd6b71

キーワードを入力すると, キーワードの文字列の文字列の文字列の文字列の文字列の文字列の文字列の文字列の文字列の文字列の文字列の文字列の文字列の文字列の文字列の文字列の文字列の文字列の文字列の文字列の文字列の文字列の文字列の文字列の文字列の文字列に
やってみました
var querystr = "asset=abc&amount=100&address=abc&timestamp=abc";
var sig = HMAC (('sha256', 'hex', querystr, secretkey);// 2番目のパラメータは全て試した
exchange.IO (("api", "POST", "/wapi/v3/withdraw.html",querystr+"&signature="+sig);または
exchange.IO("api", "POST", "/wapi/v3/withdraw.html",querystr);
分かった
{"msg":"{"code":-1105,"msg":"Parameter 'payload' was was empty."}","success":false}

exchange.IO("api", "POST", "/wapi/v3/withdraw.html?"+querystr+"&signature="+sig,"");//ru
受け取る
{"msg":"{"code":-1100,"msg":"Illegal characters found in parameter 'signature'; legal range is '^[A-Fa-f0-9]{64}$'."}","success":false}

署名がない場合
{"msg":"{"code":-1022,"msg":"Signature for this request is not valid."}","success":false}