Yubikey Data Format

• http://www.linuxjournal.com/files/linuxjournal.com/linuxjournal/articles/101/10166/10166f4.png

• 128-bit dataframe contains 48-bit “secret” ID, counters, timestamp, random number and CRC

• 128-bit dataframe encrypted with secret AES 128-bit key

• “public” ID (6 bytes, 48 bits) prepended

• 22 byte (176 bit) sequence “modhex”d to 16-character alphabet using most common 16 keys across a wide range of Latin keyboards