We are still no closer to cracking this

crack名詞是"裂縫" , 當成動詞可以當成"打破" "使破裂"

ex. The plate had a crack in it. -->盤子上有裂縫
ex. Crack the eggs into a bowl.  -->把蛋打到碗裡

不過這裡的用法是"破解難題"
ex.  He has finally cracked the system after years of painstaking research. -->經過了多年痛苦的研究,他終於破解了這個系統