a proactive alternative to key disclosure law is key escrow law, where the government holds in escrow a copy of all cryptographic keys in use, but is only permitted to use them if an appropriate warrant is issued. key escrow systems face difficult technical issues and are subject to many of the same criticisms as key disclosure law; they avoid some issues like lost keys, while introducing new issues such as the risk of accidental disclosure of large numbers of keys, theft of the keys by hackers or abuse of power by government employees with access to the keys. it would also be nearly impossible to prevent the government from secretly using the key database to aid mass surveillance efforts such as those exposed by edward snowden. the ambiguous term "key recovery" is applied to both types of systems.