PGP word list
The PGP Word List ("
bytes in a clear unambiguous way via a voice channel. They are analogous in purpose to the NATO phonetic alphabet
used by pilots, except a longer list of words is used, each word corresponding to one of the 256 distinct numeric byte values.
History and structure
The PGP Word List was designed in 1995 by
genetic algorithms to select lists of words that had optimum separations in phoneme space. The candidate word lists were randomly drawn from Grady Ward's Moby Pronunciator list as raw material for the search, successively refined by the genetic algorithms. The automated search converged to an optimized solution in about 40 hours on a DEC Alpha
, a particularly fast machine in that era.
The Zimmermann–Juola list was originally designed to be used in
fingerprints over a voice channel. This is known in PGP applications as the "biometric" representation. When it was applied to PGP, the list of words was further refined, with contributions by Jon Callas. More recently, it has been used in Zfone and the ZRTP
protocol, the successor to PGPfone.
The list is actually composed of two lists, each containing 256
syllables
; the even list has words of two syllables, the odd list has three. The two lists have a maximum word length of 9 and 11 letters, respectively. Using a two-list scheme was suggested by Zhahai Stewart.
Word lists
Here are the two lists of words as presented in the PGPfone Owner's Manual.[3]
Hex | Even Word | Odd Word |
---|---|---|
00 | aardvark | adroitness |
01 | absurd | adviser |
02 | accrue | aftermath |
03 | acme | aggregate |
04 | adrift | alkali |
05 | adult | almighty |
06 | afflict | amulet |
07 | ahead | amusement |
08 | aimless | antenna |
09 | Algol | applicant |
0A | allow | Apollo |
0B | alone | armistice |
0C | ammo | article |
0D | ancient | asteroid |
0E | apple | Atlantic |
0F | artist | atmosphere |
10 | assume | autopsy |
11 | Athens | Babylon |
12 | atlas | backwater |
13 | Aztec | barbecue |
14 | baboon | belowground |
15 | backfield | bifocals |
16 | backward | bodyguard |
17 | banjo | bookseller |
18 | beaming | borderline |
19 | bedlamp | bottomless |
1A | beehive | Bradbury |
1B | beeswax | bravado |
1C | befriend | Brazilian |
1D | Belfast | breakaway |
1E | berserk | Burlington |
1F | billiard | businessman |
20 | bison | butterfat |
21 | blackjack | Camelot |
22 | blockade | candidate |
23 | blowtorch | cannonball |
24 | bluebird | Capricorn |
25 | bombast | caravan |
26 | bookshelf | caretaker |
27 | brackish | celebrate |
28 | breadline | cellulose |
29 | breakup | certify |
2A | brickyard | chambermaid |
2B | briefcase | Cherokee |
2C | Burbank | Chicago |
2D | button | clergyman |
2E | buzzard | coherence |
2F | cement | combustion |
30 | chairlift | commando |
31 | chatter | company |
32 | checkup | component |
33 | chisel | concurrent |
34 | choking | confidence |
35 | chopper | conformist |
36 | Christmas | congregate |
37 | clamshell | consensus |
38 | classic | consulting |
39 | classroom | corporate |
3A | cleanup | corrosion |
3B | clockwork | councilman |
3C | cobra | crossover |
3D | commence | crucifix |
3E | concert | cumbersome |
3F | cowbell | customer |
Hex | Even Word | Odd Word |
---|---|---|
40 | crackdown | Dakota |
41 | cranky | decadence |
42 | crowfoot | December |
43 | crucial | decimal |
44 | crumpled | designing |
45 | crusade | detector |
46 | cubic | detergent |
47 | dashboard | determine |
48 | deadbolt | dictator |
49 | deckhand | dinosaur |
4A | dogsled | direction |
4B | dragnet | disable |
4C | drainage | disbelief |
4D | dreadful | disruptive |
4E | drifter | distortion |
4F | dropper | document |
50 | drumbeat | embezzle |
51 | drunken | enchanting |
52 | Dupont | enrollment |
53 | dwelling | enterprise |
54 | eating | equation |
55 | edict | equipment |
56 | egghead | escapade |
57 | eightball | Eskimo |
58 | endorse | everyday |
59 | endow | examine |
5A | enlist | existence |
5B | erase | exodus |
5C | escape | fascinate |
5D | exceed | filament |
5E | eyeglass | finicky |
5F | eyetooth | forever |
60 | facial | fortitude |
61 | fallout | frequency |
62 | flagpole | gadgetry |
63 | flatfoot | Galveston |
64 | flytrap | getaway |
65 | fracture | glossary |
66 | framework | gossamer |
67 | freedom | graduate |
68 | frighten | gravity |
69 | gazelle | guitarist |
6A | Geiger | hamburger |
6B | glitter | Hamilton |
6C | glucose | handiwork |
6D | goggles | hazardous |
6E | goldfish | headwaters |
6F | gremlin | hemisphere |
70 | guidance | hesitate |
71 | hamlet | hideaway |
72 | highchair | holiness |
73 | hockey | hurricane |
74 | indoors | hydraulic |
75 | indulge | impartial |
76 | inverse | impetus |
77 | involve | inception |
78 | island | indigo |
79 | jawbone | inertia |
7A | keyboard | infancy |
7B | kickoff | inferno |
7C | kiwi | informant |
7D | klaxon | insincere |
7E | locale | insurgent |
7F | lockup | integrate |
Hex | Even Word | Odd Word |
---|---|---|
80 | merit | intention |
81 | minnow | inventive |
82 | miser | Istanbul |
83 | Mohawk | Jamaica |
84 | mural | Jupiter |
85 | music | leprosy |
86 | necklace | letterhead |
87 | Neptune | liberty |
88 | newborn | maritime |
89 | nightbird | matchmaker |
8A | Oakland | maverick |
8B | obtuse | Medusa |
8C | offload | megaton |
8D | optic | microscope |
8E | orca | microwave |
8F | payday | midsummer |
90 | peachy | millionaire |
91 | pheasant | miracle |
92 | physique | misnomer |
93 | playhouse | molasses |
94 | Pluto | molecule |
95 | preclude | Montana |
96 | prefer | monument |
97 | preshrunk | mosquito |
98 | printer | narrative |
99 | prowler | nebula |
9A | pupil | newsletter |
9B | puppy | Norwegian |
9C | python | October |
9D | quadrant | Ohio |
9E | quiver | onlooker |
9F | quota | opulent |
A0 | ragtime | Orlando |
A1 | ratchet | outfielder |
A2 | rebirth | Pacific |
A3 | reform | pandemic |
A4 | regain | Pandora |
A5 | reindeer | paperweight |
A6 | rematch | paragon |
A7 | repay | paragraph |
A8 | retouch | paramount |
A9 | revenge | passenger |
AA | reward | pedigree |
AB | rhythm | Pegasus |
AC | ribcage | penetrate |
AD | ringbolt | perceptive |
AE | robust | performance |
AF | rocker | pharmacy |
B0 | ruffled | phonetic |
B1 | sailboat | photograph |
B2 | sawdust | pioneer |
B3 | scallion | pocketful |
B4 | scenic | politeness |
B5 | scorecard | positive |
B6 | Scotland | potato |
B7 | seabird | processor |
B8 | select | provincial |
B9 | sentence | proximate |
BA | shadow | puberty |
BB | shamrock | publisher |
BC | showgirl | pyramid |
BD | skullcap | quantity |
BE | skydive | racketeer |
BF | slingshot | rebellion |
Hex | Even Word | Odd Word |
---|---|---|
C0 | slowdown | recipe |
C1 | snapline | recover |
C2 | snapshot | repellent |
C3 | snowcap | replica |
C4 | snowslide | reproduce |
C5 | solo | resistor |
C6 | southward | responsive |
C7 | soybean | retraction |
C8 | spaniel | retrieval |
C9 | spearhead | retrospect |
CA | spellbind | revenue |
CB | spheroid | revival |
CC | spigot | revolver |
CD | spindle | sandalwood |
CE | spyglass | sardonic |
CF | stagehand | Saturday |
D0 | stagnate | savagery |
D1 | stairway | scavenger |
D2 | standard | sensation |
D3 | stapler | sociable |
D4 | steamship | souvenir |
D5 | sterling | specialist |
D6 | stockman | speculate |
D7 | stopwatch | stethoscope |
D8 | stormy | stupendous |
D9 | sugar | supportive |
DA | surmount | surrender |
DB | suspense | suspicious |
DC | sweatband | sympathy |
DD | swelter | tambourine |
DE | tactics | telephone |
DF | talon | therapist |
E0 | tapeworm | tobacco |
E1 | tempest | tolerance |
E2 | tiger | tomorrow |
E3 | tissue | torpedo |
E4 | tonic | tradition |
E5 | topmost | travesty |
E6 | tracker | trombonist |
E7 | transit | truncated |
E8 | trauma | typewriter |
E9 | treadmill | ultimate |
EA | Trojan | undaunted |
EB | trouble | underfoot |
EC | tumor | unicorn |
ED | tunnel | unify |
EE | tycoon | universe |
EF | uncut | unravel |
F0 | unearth | upcoming |
F1 | unwind | vacancy |
F2 | uproot | vagabond |
F3 | upset | vertigo |
F4 | upshot | Virginia |
F5 | vapor | visitor |
F6 | village | vocalist |
F7 | virus | voyager |
F8 | Vulcan | warranty |
F9 | waffle | Waterloo |
FA | wallet | whimsical |
FB | watchword | Wichita |
FC | wayside | Wilmington |
FD | willow | Wyoming |
FE | woodlark | yesteryear |
FF | Zulu | Yucatan |
Examples
Each byte in a bytestring is encoded as a single word. A sequence of bytes is rendered in
network byte order
, from left to right. For example, the leftmost (i.e. byte 0) is considered "even" and is encoded using the PGP Even Word table. The next byte to the right (i.e. byte 1) is considered "odd" and is encoded using the PGP Odd Word table. This process repeats until all bytes are encoded. Thus, "E582" produces "topmost Istanbul", whereas "82E5" produces "miser travesty".
A PGP public key fingerprint that displayed in hexadecimal as
E582
94F2
E9A2
2748
6E8B
061B
31CC
528F
D7FA
3F19
would display in PGP Words (the "biometric" fingerprint) as
topmost Istanbul
Pluto vagabond
treadmill Pacific
brackish dictator
goldfish Medusa
afflict bravado
chatter revolver
Dupont midsummer
stopwatch whimsical
cowbell bottomless
The order of bytes in a bytestring depends on endianness.
Other word lists for data
There are several other word lists for conveying data in a clear unambiguous way via a voice channel:
- the NATO phonetic alphabet maps individual letters and digits to individual words
- the S/KEY system maps 64 bit numbers to 6 short words of 1 to 4 characters each from a publicly accessible 2048-word dictionary. The same dictionary is used in RFC 1760 and RFC 2289.
- the Diceware system maps five base-6 random digits (almost 13 bits of entropy) to a word from a dictionary of 7,776 distinct words.
- the Electronic Frontier Foundation has published a set of improved word lists based on the same concept[4]
- FIPS 181: Automated Password Generatorconverts random numbers into somewhat pronounceable "words".
- mnemonic encoding converts 32 bits of data into 3 words from a vocabulary of 1626 words.[5]
- what3words encodes geographic coordinates in 3 dictionary words.
- the BIP39 standard permits encoding a cryptographic key of fixed size (128 or 256 bits, usually the unencrypted master key of a .
- Like the PGP word list, the Bytewords standard maps each possible byte to a word. There is only one list, rather than two. The words are uniformly four letters long and can be uniquely identified by their first and last letters
References
- This article incorporates material that is copyrighted by PGP Corporation and has been licensed under the GNU Free Documentation License. (per Jon Callas, CTO, CSO PGP Corporation, 4-Jan-2007)
- S2CID 10385500.
- Bibcode:1996cmp.lg....8021J.
- ^ "Archived copy". web.mit.edu. Archived from the original on 26 March 2010. Retrieved 12 January 2022.
{{cite web}}
: CS1 maint: archived copy as title (link) - ^ "EFF's New Wordlists for Random Passphrases". 19 July 2016.
- ^ mnemonic encoding Archived 2008-03-02 at the Wayback Machine and updated code