sign (Net::SSH::Authentication::Agent)

         # File lib/net/ssh/authentication/agent.rb, line 118
    118:     def sign(key, data)
    119:       type, reply = send_and_wait(SSH2_AGENT_SIGN_REQUEST, :string, Buffer.from(:key, key), :string, data, :long, 0)
    120:
    121:       if agent_failed(type)
    122:         raise AgentError, "agent could not sign data with requested identity"
    123:       elsif type != SSH2_AGENT_SIGN_RESPONSE
    124:         raise AgentError, "bad authentication response #{type}"
    125:       end
    126:
    127:       return reply.read_string
    128:     end