Coldbit Passphrase can be purchased at I was excited to see this because it’s the same design as the CryptoHex, which I was never able to get my hands on. Coldbit says that this is designed to store the passwords to your BIP39 encrypted seed phrases, but there is also enough room to store a 24 word seed phrase on it.


This was by far the most challenging device to etch and stamp because of its hexagonal shape. One thing I noted about the similar CryptoHex was that they were shipping with 3D printed templates to aid in stamping, which I think would be an awesome addition given the experience I had with the CryptoTag’s stamping bit template. Here’s the CryptoHex video that shows the stamping template.

Heat Stress Test

Performed admirably; while the freehand etching was barely readable, the stamping was quite readable other than the fact that they were partial stamps. The template-based etching seems to be the best option for this shape of device.

Corrosion Stress Test

Freehand etching was wiped clean. Template based etching was readable, as was stamping. Does this mean that if left in acid long enough, the other words would also be wiped clean? Perhaps, though it’s hard to say how long it would take.

Crush Stress Test

No additional data loss.