def self.signed_params(params, options = {})
params.merge!({
'AWSAccessKeyId' => options[:aws_access_key_id],
'SignatureMethod' => 'HmacSHA256',
'SignatureVersion' => '2',
'Timestamp' => Time.now.utc.strftime("%Y-%m-%dT%H:%M:%SZ"),
'Version' => options[:version]
})
body = ''
for key in params.keys.sort
unless (value = params[key]).nil?
body << "#{key}=#{escape(value.to_s)}&"
end
end
string_to_sign = "POST\n#{options[:host]}:#{options[:port]}\n#{options[:path]}\n" << body.chop
signed_string = options[:hmac].sign(string_to_sign)
body << "Signature=#{escape(Base64.encode64(signed_string).chomp!)}"
body
end