Secure device update by passing encryption and data together

A system for updating firmware of a device, the device comprising:

• a first memory of the device;
• a second memory of the device configured with firmware, wherein the first memory is different than the second memory;
• a processor, wherein the processor is configured to:
• receive in an update package an encrypted firmware and a decryption engine including a decryption algorithm for decrypting the encrypted firmware;
• load the decryption engine into the first memory of a device;
• obtain a pre-stored encryption key from the second memory of the device, wherein the second memory is a different type of memory than the first memory;
• and
• decrypting the encrypted firmware using the encryption key and the decryption engine, wherein the decryption of the encrypted firmware occurs in the first memory;
• wherein the first memory is configured to authenticate the decryption engine prior to receiving the encrypted firmware by comparing a digest stored in the device to a computed digest of the decryption engine;
• wherein the authentication comprises comparing, in the first memory, a first digest and a second digest, wherein the first digest is generated by a provider of the decryption algorithm, wherein the first digest is stored in the device and the first digest corresponds to the decryption algorithm and the second digest corresponds to an output of multiple XOR operations of selected bootloader code parts with the decryption algorithm.