verify_oauth.rb

consumer_secret = <<END_OF_STRING 
-----BEGIN PUBLIC KEY-----
KEY HERE HERE 
-----END PUBLIC KEY-----
END_OF_STRING
      
request_proxy = OAuth::RequestProxy::ActionControllerRequest.new(request)
signature_base_string = request_proxy.signature_base_string
public_key = OpenSSL::PKey::RSA.new(consumer_secret).public_key
logger.error "public_key returned: #{public_key} "
logger.error "params[:oauth_signature]: #{params[:oauth_signature]}"
decoded_sig = Base64.decode64(params[:oauth_signature]) rescue ''
logger.error "Decode returned: #{decoded_sig} "
is_verified = public_key.verify(OpenSSL::Digest::SHA1.new,decoded_sig,signature_base_string)
logger.error "Signature verification returned: #{is_verified} "
      
render :text => "OAuth access denied", :status => :unauthorized  unless is_verified