Secured communications in medical monitoring systems
In one embodiment, a method for secured communication between a medical sensor and a computing device includes receiving, by the medical sensor, an authentication request from the computing device. The method includes generating, based on values provided in the authentication request, a challenge-response message for the computing device. The method includes receiving, from the computing device, a responsive challenge-response message. The method includes verifying that the responsive challenge-response message includes an expected value and corresponds to an expected format. The method includes, in response to verifying the responsive challenge-response message, sending a sensor secret value to the computing device.
1. A method comprising:
receiving, by a first computing device from a sensor, a sensor secret value;
receiving, by the first computing device from the sensor, a set of encrypted data created using a first cryptographic operation on unencrypted data based on a first key derived from the sensor secret value, wherein the first cryptographic operation comprises:
segmenting the unencrypted data into a series of data blocks;
segmenting each data block into more than one words; and
for each data block, performing add-rotate-xor operations on the more than one words of the block, wherein the add-rotate-xor operations comprise:
for each data block:
rotating bits of a first word of the more than one words of the block by a first fixed amount;
adding a second word of the more than one words of the block;
performing a bitwise xor operation of the first key into the first word;
rotating bits of the second word by a second fixed amount; and
performing a bitwise xor operation of the first word into the second word;
deriving, by the first computing device, the first key based on the sensor secret value; and
decrypting, by the first computing device, the set of encrypted data using the derived first key with the first cryptographic operation.
2. The method of claim 1 , further comprising:
encrypting the decrypted data using a second key and a second cryptographic function, wherein the second key comprises information unique to the first computing device and random values generated by the first computing device; and
transmitting the data encrypted using the second key to a second computing device.
3. The method of claim 2 , wherein second cryptographic function is different from the first cryptographic function and is a more computationally-complex cryptographic function than the first cryptographic function.
4. The method of claim 2 , wherein the data encrypted using the second key is transmitted to second computing device via wired or wireless communication.
5. The method of claim 2 , wherein the data encrypted using the second key is transmitted using a packet-level-encoding computing protocol.
6. The method of claim 2 , further comprising:
decrypting, by the second computing device, the data encrypted using the second key; and
transmitting the decrypted data previously encrypted using the second key to a third computing device after encrypting that data with a third cryptographic function based on a third key, wherein the first key, the second key, and the third key are all different and are all derived from different root values and wherein the first cryptographic function, second cryptographic function, and third cryptographic function are all different.
7. The method of claim 1 , wherein the sensor secret value comprises unique values associated with the sensor and random values generated by the sensor.