Accessing Ivona Speech Cloud with Ruby - ruby

Question

I am trying to access Ivona Speech Cloud using Ruby.
I have ported one of the code examples I found to Ruby, but I probably did something wrong at authenticating the request, since I am getting an error.
This is my implementation:
require 'http' # the gem
require 'openssl'
require 'pp'
def sign key, date, region, service, text
k_date = OpenSSL::HMAC.digest('sha256', "AWS4" + key, date)
k_region = OpenSSL::HMAC.digest('sha256', k_date, region)
k_service = OpenSSL::HMAC.digest('sha256', k_region, service)
k_signing = OpenSSL::HMAC.digest('sha256', k_service, "aws4_request")
signature = OpenSSL::HMAC.digest('sha256', k_signing, text)
signature
end
def run
access_key = "GDxxxxxxxxxxxxxxxxRA"
secret_key = "QtxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxlE"
region = 'eu-west-1'
date = '20160808'
service = 'tts'
body = {"Input" => {"Data" => "Hello world"}}
endpoint = "https://#{service}.#{region}.ivonacloud.com/CreateSpeech"
signature = sign secret_key, date, region, service, 'Hello World'
headers = {
"Content-Type" =>"application/json",
"Authorization" => "AWS4-HMAC-SHA256",
"Credential" => "#{access_key}/#{date}/#{region}/#{service}/aws4_request",
"SignedHeaders" => "content-type;host;x-amz-content-sha256;x-amz-date",
"Signature" => "#{signature}",
}
res = HTTP.headers(headers).post(endpoint, json: body)
p res
end
run
This is the error I am getting (line broken for legibility):
#<HTTP::Response/1.1 403 Forbidden
{"X-Amzn-Requestid"=>"18a44dd8-6dc3-11e6-808f-975692d1ee55",
"X-Amzn-Errortype"=>"IncompleteSignatureException:http://internal.amazon.com/coral/com.amazon.coral.service/",
"Content-Type"=>"application/json",
"Content-Length"=>"293",
"Date"=>"Mon, 29 Aug 2016 08:32:18 GMT"}>
Any assistance is appreciated

Answer 1

I would suggest using the AWS4 gem to help with this. I've made similar calls using the following format:
signer = ::AWS4::Signer.new(
access_key: "YOUR_ACCESS_KEY",
secret_key: "YOUR_SECRET_KEY",
region: "us-east-1"
)
aws_headers = {
"Content-Type" => "application/json; charset=utf8",
"Date" => Time.now.iso8601.to_s,
"Host" => "tts.us-east-1.ivonacloud.com"
}
uri = URI(endpoint)
body_params = {"Input":{"Data":"Hello world"}}.to_json
headers = signer.sign("POST", uri, aws_headers, body_params)
res = HTTP.headers(headers).post(endpoint, body: body_params)