Have you checked that the string you construct for the signature is actually as the documentation says?

You interpolate %params into the string, but you don't specify the order of the keys.

My hint is to print out the string before you compute the mac for it, and manually compare the string with what the documentation says.

"The following have to be combined into a single string:" which you don't.

i have tried to do this

my $apiKey = 'BITSTAMP pEF7aWa';
my $apiSecret = 'sWNuYX4QS';

my $urlcb = "https://www.bitstamp.net";
my $url = URI->new($urlcb);
my $urlpath = $url->path('/api/v2/usdt_withdrawal/');

my @Char = ('a'..'z');
my $Leng = 36;
my $RandomChar = '';
for (1..$Leng) {
$RandomChar .= $Char[int rand @Char];
}

my $timestamp = int (gettimeofday * 1000);
my $nonce = $RandomChar;

my $Query = URI->new();
$Query->query_form(
'currency' => "USDT",
'network' => "ethereum",
'address'   => "#wallet",
'amount' => "4"
);

my $API_Version = 'v2';
my $ContentType = "application/x-www-form-urlencoded";
my $signature = hmac_sha256_hex($apiKey.'POST'.$urlcb.$urlpath.$Conten
+tType.$nonce.$timestamp.$API_Version.$Query, $apiSecret);

my %payload = (
"X-Auth" => $apiKey,
"X-Auth-Signature" => $signature,
"X-Auth-Nonce" => $nonce,
"X-Auth-Timestamp" => $timestamp,
"X-Auth-Version" => $API_Version,
"Content-Type" => $ContentType
);


print $Query;
print $signature;
[download]

but am still getting this error

Error: {"status": "error", "reason": "Invalid signature", "code": "API0005"}

i have even tried to follow the API example in other Languages https://www.bitstamp.net/api/#section/Authentication/Authentication-examples

The string you compute for your signature does not match the string from the example code.

For debugging, print out the string you compute the signature over, and compare that to the example code string.

message = 'BITSTAMP ' + api_key + \
    'POST' + \
    'www.bitstamp.net' + \
    '/api/v2/user_transactions/' + \
    '' + \
    content_type + \
    nonce + \
    timestamp + \
    'v2' + \
    payload_string
[download]

Your code should be:

my $msg = $apiKey.'POST'.$urlcb.$urlpath.$ContentType.$nonce.$timestam
+p.$API_Version.$Query, $apiSecret;
print "Computing signature over [$msg]\n";
my $signature = hmac_sha256_hex($msg, $apiSecret);
[download]

Then, compare the output of that part with the message as it is constructed in the documentation. There are differences between the two.