Initial commit

app/controllers/multipart_signatures_controller.rb

@@ -0,0 +1,33 @@
+class MultipartSignaturesController < ApplicationController
+  skip_after_action :verify_authorized
+
+  def create
+    render plain: hmac_data, status: 200
+  end
+
+  private
+
+  def hmac_data
+    aws_secret = ENV['AWS_SECRET_ACCESS_KEY']
+    timestamp = params[:datetime]
+
+    # TESTING UTF-8 encoding
+    aws_secret = aws_secret.encode('UTF-8')
+    details = params[:to_sign].encode('UTF-8')
+
+    date = hmac("AWS4#{aws_secret}", timestamp[0..7])
+    region = hmac(date, ENV["AWS_REGION"])
+    service = hmac(region, "s3")
+    signing = hmac(service, 'aws4_request')
+
+    hexhmac(signing, details)
+  end
+
+  def hmac(key, value)
+    OpenSSL::HMAC.digest(OpenSSL::Digest.new('sha256'), key, value)
+  end
+
+  def hexhmac(key, value)
+    OpenSSL::HMAC.hexdigest(OpenSSL::Digest.new('sha256'), key, value)
+  end
+end