So, maybe post what the script outputs, and then tell us part-by-part why/how it is the same. You obviously haven't done this.

There is a difference in generating the signature string that I spot from reading the documentation and your code, but you will have to find it yourself. This is called "debugging" and I expect you to make a honest try at it.

i have been able to make this API to work, and am successfully interacting with it now

Am trying to make a post with this data

my $url_query = "currency=usdt"."&amount=20"."&address=0x55Dc816924e33
+CA50830A"."&destination_tag=None";
[download]

but am getting this error

{"status": "error", "reason": {"amount": ["This field is required."]}}
[download]

 API Documentation Section : https://www.bitstamp.net/api/#tag/Withdrawals/operation/RequestCryptoWithdrawal

Full code

#!/usr/bin/perl

use strict;
use warnings;
use LWP::UserAgent;
use Digest::SHA qw(hmac_sha256_hex);
use UUID::Tiny ':std';
use URI::Escape;
use JSON;
use Time::HiRes qw(time);
use JSON::XS;



sub write_call_back {
    my ($data, $userp) = @_;
    ${$userp} .= $data;
    return length($data);
}

sub url_encode {
    my ($data) = @_;
    return uri_escape($data);
}

my $api_key = "api_key";
my $api_secret = "api_secret";

my $timestamp = int(time() * 1000);

my $nonce = create_uuid_as_string(UUID_V4);

my $x_auth = "BITSTAMP $api_key";
my $x_auth_nonce = $nonce;
my $x_auth_timestamp = $timestamp;
my $x_auth_version = "v2";
my $content_type = "application/x-www-form-urlencoded";
my $payload = url_encode('{"offset":1}');

my $http_method = "POST";
my $url_host = "www.bitstamp.net";
my $url_path = "/api/v2/usdt_withdrawal/?";
my $url_query = "currency=usdt"."&amount=20"."&address=0x55Dc816924e33
+CA50830A"."&destination_tag=None";

my $data_to_sign = join('', 
    $x_auth, $http_method, $url_host, $url_path, $url_query,
    $content_type, $x_auth_nonce, $x_auth_timestamp, $x_auth_version, 
+$payload
);


my $x_auth_signature = hmac_sha256_hex($data_to_sign, $api_secret);


my $ua = LWP::UserAgent->new;

my $url = "https://$url_host$url_path$url_query";

my $req = HTTP::Request->new(POST => $url);
$req->header('X-Auth' => $x_auth);
$req->header('X-Auth-Signature' => $x_auth_signature);
$req->header('X-Auth-Nonce' => $x_auth_nonce);
$req->header('X-Auth-Timestamp' => $x_auth_timestamp);
$req->header('X-Auth-Version' => $x_auth_version);
$req->header('Content-Type' => $content_type);
$req->content($payload);

my $resp = $ua->request($req);

if ($resp->is_success) {
    print $resp->content;
} else {
    print "HTTP POST error code: ", $resp->code, "\n";
    print "HTTP POST error message: ", $resp->message, "\n";
}
[download]

Use the techniques outlined in Basic debugging checklist to determine precisely what you are sending to the API endpoint. Then look in the API documentation for that endpoint to see precisely what it expects to be sent.

If what you are sending does not match the spec then alter your code until it does.

If what you are sending does match the spec but still gives an error then contact the API provider to enquire about the problem.

---

🦛

hippo's advice is correct. Compare what you are sending against what you think you are sending.

See (for example) LWP::Debug for a good approach to see all the data you send:

use LWP::UserAgent;
my $ua = LWP::UserAgent->new;
$ua->add_handler("request_send",  sub { shift->dump; return });
$ua->add_handler("response_done", sub { shift->dump; return });

...
[download]

I hazard a guess that it expects a floating point number. The documentation you linked shows the type as "number", not "integer".

Try "20.0" instead of "20".

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