A leaked document from the Drug Enforcement Administration (DEA) has revealed Apple's iMessage service is hindering its ability to eavesdrop on drug suspects' communications. Obtained by CNET, the DEA's intelligence note — titled 'Apple's iMessages: A Challenge For DEA Intercept' — highlights that encryption used to secure Apple's messaging service makes it "impossible to intercept iMessages between two Apple devices," obstructing agents' attempts to obtain a complete history of suspects' messages.

"It is impossible to intercept iMessages between two Apple devices."

Apple's iMessage encryption was noticed by agents at the agency's San Jose division on February 21st (despite it launching October 2011), while preparing a request to perform electronic surveillance under Title III of the Federal Wiretap Act. The DEA says that it became aware of Apple's encryption when it "became apparent that not all text messages were being captured" from data supplied by Verizon, and that their target was using iMessage to communicate with associates.

Last year, BlackBerry was forced to open a service center in Mumbai to allow "lawful access" by the Indian government to its secure messaging and email services in cases of suspected criminal activity. Attempting to gain access to electronic data sent and received by US citizens, the FBI allegedly began drafting a proposal to amend existing laws to permit interception, acknowledging that surveillance efforts were "going dark" because companies were unable or unwilling to provide wiretaps. While Apple declined to comment, its online terms state that it will share registration data or account information with law enforcement agences if it believes it is "reasonably necessary."