Modhex decode
Modhex decode. Runs on your device, nothing is uploaded.
Modhex decode reads Yubico's own cbdefghijklnrtuv alphabet two characters at a time, each pair giving one byte's high and low nibble, once whitespace is stripped and text lowercased. An odd character count is refused, and a character outside those sixteen symbols is named with its offset. This is the same shape as decode-hex, over sixteen letters Yubico picked for keyboard safety.
Questions
What alphabet does modhex use?
Yubico's own cbdefghijklnrtuv, sixteen characters chosen to be unambiguous across international keyboard layouts.
How is this different from decode-hex?
Same nibble-per-character shape, a different sixteen-symbol alphabet in place of 0-9a-f.
What happens with an odd character count?
The tool refuses and names the count, because modhex always encodes whole bytes as pairs of characters.
What happens with an invalid character?
The tool refuses, naming the character and its offset.
Where does modhex show up in practice?
YubiKey one-time-password output, which this alphabet was designed for.