Imports gopkg.in/goyy/goyy.v0/comm/log gopkg.in/goyy/goyy.v0/util/strings gopkg.in/goyy/goyy.v0/web/controller gopkg.in/goyy/goyy.v0/web/xhttp Standard library imports bytes crypto/hmac crypto/rand crypto/sha256 encoding/binary image image/color image/png io math strconv