PGP Word List

The PGP wordlist is a standardized set of words associated with each numeric value (from 0 to 255) used to verify and communicate cryptographic key fingerprints.

Sometimes called a biometric word list, it facilitates the vocal (or written) communication of these signatures by avoiding transcription errors due to confusion between numbers or letters.

To encode data with a PGP wordlist, each byte of the data is converted into corresponding words from the PGP list.

Each byte is associated with a specific word in 2 predefined lists. Each list is 256 words long (indexed from 00 to FF).

The first list (called even) contains 2-syllable words, the second list (called odd) contains 3-syllable words so as not to confuse them. Here is an excerpt:

Each even byte is encoded with the corresponding word in the even list, and each odd byte is encoded with the corresponding word in the odd list. (NB: the bytes are 0-indexed, the first one is in position 0, so it is encoded with the even list)

To decode PGP words, you do the reverse of encoding: convert each word from the PGP list into its corresponding byte (in hexadecimal form) in order to reconstruct the original data.

PGP list words have a maximum length of 11 letters respectively (to be precise 9 letters for the even list, and 11 letters for the odd list).

Even list words have 2 syllables, odd list words have 3 syllables.

PGP list words are specially chosen to be easily distinguishable, even under difficult communication conditions.