Understanding entropy and the ColdCard hack

To understand the ColdCard hack and entropy, the impacted wallets had roughly 40-72 bits of entropy (a measure of randomness). Truly random 12 word seedphrases give you 128 bits of entropy. Truly random 24 word seedphrases give you 256 bits of entropy. While that doesn't sound like a big deal, entropy is measured on an exponential scale (powers of 2). To conceptualise this, imagine the entire search space (total combinations) for 40 bits of entropy = 1 grain of rice then:
40 bits of entropy – 1 grain
72 bits – enough rice to fill a warehouse
128 bits – roughly the entire mass of Earth in rice grains
256 bits – a pile of rice that contains more atoms than in the observable universe.

This is why the flaw in the code was so damaging and able to be hacked. Cold storage is not the issue, the way the seedphrase was generated was the issue which made it so easy for an ordinary machine to crack. A true 256 bit seedphrase is safe and secure.