We are supporting RubyGems as a package manager. Ruby 1.9 and newer versions are shipped with RubyGems built-in, so it should be available on your system by default. You might need an update, please check the instructions on the RubyGem’s Downloads page for more information.

If RubyGems is installed, you can install the escher gem by:

gem install escher


From Ruby 1.9, your installed gems are autoloaded automatically, you can start using Escher after installation.

The library has 3 interfaces you can call. You can sign an HTTP request, you can presign a URL and you can validate a signed HTTP request or presigned URL (with the same method).

Signing a Request

Escher works by calculating a cryptographic signature of your request, and adding it (and other authentication information) to the request. Usually you will want to add the authentication information by appending extra headers to it. Let’s say you want to send a signed POST request to using the GuzzleHttp library:

require 'escher'
require 'net/http'

escher ='example/credential/scope', {})

request_data = {
   method: 'GET',
   uri: '/api/examples',
   headers: [['Content-Type', 'application/json'], ['host', '']],

escher.sign!(request_data, { api_key_id: 'YOUR ACCESS KEY ID', api_secret: 'YOUR SECRET' })

request ='/api/examples')
request_data[:headers].each do |header|
   request[header.first] = header.last

response ='').request(request)

Presigning a URL

In some cases you may want to send authenticated requests from a context where you cannot modify the request headers, e.g. when embedding an API generated iframe. You can however generate a presigned URL, where the authentication information is added to the query string.

require 'escher'
require 'net/http'

escher ='example/credential/scope', {})
client = {api_key_id: 'YOUR ACCESS KEY ID', api_secret: 'YOUR SECRET'}

presigned_url = escher.generate_signed_url("", client)

Validating a request

You can validate a request signed by the methods described above. For that you will need a database of the access keys and secrets of your clients. Escher accepts any kind of object as a key database that implements the ArrayAccess interface. (It also accepts plain arrays, however it is not recommended to use a php array for a database of API secrets - it’s just there to ease testing)