US 11,853,429 B2
Measured restart of microcontrollers
Stavros Volos, Cambridge (GB); Colin Doak, Bristol (GB); Simon Douglas Chambers, Bristol (GB); David Ruggles, Bristol (GB); Richard Neal, Bristol (GB); Cédric Alain Marie Fournet, Cambridge (GB); Kapil Vaswani, Bangalore (IN); and Balaji Vembu, Redmond, WA (US)
Assigned to Microsoft Technology Licensing, LLC, Redmond, WA (US)
Filed by Microsoft Technology Licensing, LLC, Redmond, WA (US)
Filed on Jul. 13, 2021, as Appl. No. 17/374,900.
Prior Publication US 2023/0020838 A1, Jan. 19, 2023
Int. Cl. G06F 21/57 (2013.01); G06F 9/4401 (2018.01)
CPC G06F 21/572 (2013.01) [G06F 9/4405 (2013.01); G06F 2221/033 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A computing device comprising:
a first microcontroller on the computing device, the first microcontroller comprising a first immutable bootloader and first mutable firmware; and
a second microcontroller on the computing device, the second microcontroller comprising a second immutable bootloader and second mutable firmware,
the first immutable bootloader having stored therein an attestation of the first mutable firmware including:
a unique device secret burnt into hardware of the computing device, and
a measurement of the second mutable firmware from the second immutable bootloader, and
wherein the first immutable bootloader accepts the measurement of the second mutable firmware upon the measurement being in an initial message that the first microcontroller receives from the second microcontroller after the first microcontroller has restarted.