Hahaha, I was doing something similar on my end. I found that if I used wget I could get a non-corrupt copy of the .ipk.
so i downloaded the ones I needed directly to the SD card where I wanted them
wget "http://downloads.arduino.cc/openwrtyun/1/packages/kmod-usb-hid_3.3.8-1_ar71xx.ipk"
wget "http://downloads.arduino.cc/openwrtyun/1/packages/kmod-hid_3.3.8-1_ar71xx.ipk"
wget "http://downloads.arduino.cc/openwrtyun/1/packages/kmod-input-core_3.3.8-1_ar71xx.ipk"
wget "http://downloads.arduino.cc/openwrtyun/1/packages/kmod-input-evdev_3.3.8-1_ar71xx.ipk"