We propose a system which enables access to the user's Personal Health Record (PHR) in the event of emergency. The
access typically occurs in an ad-hoc and spontaneous manner and the user is usually unconscious, hence rendering the
unavailability of the user's password to access the PHR. The
proposed system includes a smart card carried by the user
at all time and it is personalized with a pseudo secret, an
URL to the PHR Server, a secret key shared with the PHR
Server and a number of redemption tokens generated using
a hash chain. In each emergency session, a one-time use
redemption token is issued by the smart card, allowing the
emergency doctor to retrieve the user's PHR upon successful authentication of his credentials and validation of the
redemption token. The server returns the PHR encrypted
with a one-time session key which can only be decrypted by
the emergency doctor. The devised interaction protocol to
facilitate emergency access to the user's PHR is secure and
efficient
