Hardware wallet teardowns and side channel attacks Most of the popular hardware wallets appear to be based on well established open source cryptography. 

Which hardware wallets have been submitted to extensive teardowns and side channel attack testing?
The researcher Jochen Hoenicke has done some work on the Trezor. He was able to extract the private key by monitoring the power cable with an oscilloscope.

Trezor has since updated the firmware to defeat the described attack.