Patent ID: 8885833

Claim:
A method implemented in a key recovery service, the method comprising: receiving, by the key recovery service, a key recovery request for a device; identifying a recovery key associated with the device; identifying a first one-time recovery credential in a sequence of multiple one-time recovery credentials, previous one-time recovery credentials in the sequence being indeterminable given subsequent one-time recovery credentials in the sequence, the first one-time recovery credential in the sequence being identified by an identifier that is generated using a single hash function that includes the recovery key as an input; generating, under control of a processor, the first one-time recovery credential in the sequence by using the single hash function that is also used to generate the identifier of the first one-time recovery credential; returning the first one-time recovery credential in response to the key recovery request; responsive to returning the first one-time recovery credential, causing access to the recovery key associated with the device; and monitoring key recovery requests and reporting an event when the identifier of the first one-time recovery credential is at least a threshold amount earlier in the sequence of multiple one-time recovery credentials than an identifier included in a previously received key recovery request.