The present invention is notably directed to a method for allowing an
operating system, or OS, to access an encrypted
data storage system of a computer (10), wherein: the
data storage system (11) comprises: a partition (122); and first encrypted data units (120) that comprise partition table data of said
data storage system; and said computer (10) is connectable to an external device (20) comprising: a boot
loader (24) for an
external OS (112) that is not installed on the computer; and partitioning information (22) capturing an expected location of said partition (122) in the data storage
system; and wherein second encrypted data units (220) that comprise reference partition table data for said data storage
system are available from said computer (10) or said external device, the method comprising: upon connection (S21) of said external device (20) to the computer, instructing to boot (S23) the computer (10) from said boot
loader (24); and during or after
booting of the computer: comparing (S25) the first (120) and second encrypted data units (220); and if (S27) the first and second encrypted data units match, allow (S28) the
external OS (112) to access, based on the partitioning information (22) stored on the external device, one or more data units (14) of said partition on the data storage
system (11). The present invention is further directed to related devices, systems and
computer program products.