Bitstamp API signature in Ruby - ruby

Question

I'm trying to access balance of Bitstamp account with API.
secret = "secret"
key = "key"
nonce = (1000*Time.now.to_f).to_i.to_s
client_id = "123123"
message = nonce + client_id + key
signature = HMAC::SHA256.hexdigest(secret, message).upcase
puts open("https://www.bitstamp.net/api/balance/?nonce=#{nonce}&key=#{key}&signature=#{signature}").read
it clearly generates all required attributes
https://www.bitstamp.net/api/balance/?nonce=1392137355403&key=key&signature=955A3FFC6FEBE69385B9503307873DBCD21E9B7B8EDE67817FFF70961189CE50
yet the error says attributes are missing, why?
{"error": "Missing key, signature and nonce parameters"}

Answer 1

The problem was that I was sending the request as GET instead of POST. Here is the full code I am using now that works.
require 'open-uri'
require 'json'
require 'base64'
require 'openssl'
require 'hmac-sha2'
require 'net/http'
require 'net/https'
require 'uri'
def bitstamp_private_request(method, attrs = {})
secret = "xxx"
key = "xxx"
client_id = "xxx"
nonce = nonce_generator
message = nonce + client_id + key
signature = HMAC::SHA256.hexdigest(secret, message).upcase
url = URI.parse("https://www.bitstamp.net/api/#{method}/")
http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true
data = {
nonce: nonce,
key: key,
signature: signature
}
data.merge!(attrs)
data = data.map { |k,v| "#{k}=#{v}"}.join('&')
headers = {
'Content-Type' => 'application/x-www-form-urlencoded'
}
resp = http.post(url.path, data, headers)
console_log "https://www.bitstamp.net/api/#{method}/"
resp.body
end
def nonce_generator
(Time.now.to_f*1000).to_i.to_s
end