The engineers reverse-engineered the phone's encryption system to understand its security features.

reverse-engineered 是动词 reverse-engineer 的过去式形式。reverse-engineer 由前缀 reverse-（表示"反向"）和 engineer（"设计、工程"）组成，字面意思是"反向设计"，即通过拆解成品来分析其工作原理和构造方法，也就是"逆向工程"。