he quit the job, citing "personal reasons."He won't be handing in his (encryption) keys until a successor is found, GCHQ said.
In a letter to the UK's foreign secretary, Boris Johnson, Hannigan said that he was "proud" of the work he has overseen at the eavesdropping concrete doughnut.
He flagged up the National Cyber Security Centre as one of GCHQ's "achievements" under his tenure.
"While this work must remain secret, you will know how many lives have been saved in this country and overseas by the work of GCHQ," he added in his missive to Johnson. more
