Biometric word list
A biometric word list is a list of words that can be used to authentically and reliably communicate binary information by voice. The words in the list each correspond to one of the 256 unique byte values, and are carefully chosen for their (reliable) phonetic distinctness. The properties of the human voice serve as the authentication mechanism. The idea was originated by Phil Zimmermann, the inventor of PGP, and Patrick Juola, a computational linguist.The first (and only?) biometric word list is one developed by Zimmermann and Juola, with the assistance of Zhahai Stewart and Grady Ward. It was developed to permit the verbal authentication of Diffie-Hellman key exchange, and of cryptographic key fingerprints. The information conveyed using a biometric word list can also be conveyed by simply reading the hexadecimal numbers. However, some numbers sound similar to each other ("five" and "nine"; "B" and "D"; etc.) and can lead to errors in "transmission", and so the conversion to words is used. It is similar to the use of the military alphabet for the communication of letters.
The Zimmermann/Juola list is actually composed of two parallel lists, one of two-syllable words, the other of three-syllable words. This is done to address the tendency of people to transpose consecutive words, duplicate words, and omit words when reading aloud lists of random words. To compose the verbal equivalent of a numeric value, the two lists are used in an alternating manner; the first byte is represented by the appropriate word in the two-syllable list; the next byte by the appropriate word in the three-syllable list; etc.
The first 5 words in the parallel lists are as follows:
| Byte | Corresponding words | |
|---|---|---|
| (hex value) | Two-Syllable | Three-Syllable |
| 00 | aardvark | adroitness |
| 01 | absurd | adviser |
| 02 | accrue | aftermath |
| 03 | acme | aggregate |
| 04 | adrift | alkali |
Thus, for example, the hexadecimal number 00 01 02 03 04 (with spaces added for clarity of demonstration) is represented by the word sequence, "aardvark adviser accrue aggregate adrift"; the hex number 010101 is represented by "absurd adviser absurd".
