Thank you so much

really? is wonderful

decode with the key is dependent of encode text if the password is not long enough, isn't it?

i got it, thank you. and i complete a Chinese Test Case, and the next? how?

i guess i really understood this kate, e.g. password: pizza; alphabet: lowercase; first encode "asodakme", and key is pizza + asodakme. then deocde previous encode result, key is not change, but next to decode "yiuzslrdpl", and expected value is "javascript", so, key should be pizza + javascript. i can't get "javascript" because the encode is after decode...
sorry, my English is terrible, and i not really understand the description mean. i look up some Chinese informations

Why? "it's a shift cipher!" & "javacript" Test Case's decode before encode. how can i know decode key string...什么鬼！！！