ˈoʊpaɪ ˈɪmplɪmənts ɐ wˈʌntˈaɪm pˈæswɜːd ˌoʊtˌiːpˈiː skˈiːm bˈeɪst ˌɔn ˈɛs slˈæʃ kˌeɪˌiːwˈaɪ, wˌɪtʃ wɪl ɹᵻkwˈaɪɚɹ ɐ sˈiːkɹᵻt pˈæsfɹeɪz nˌɑːt ˈɛkoʊd tə dʒˈɛnɚɹˌeɪt ɐ pˈæswɜːd fɚðə kˈɜːɹənt sˈɛʃən, ɔːɹ ɐ lˈɪst ʌv pˈæswɜːdz juː kæn pɹˈɪnt ænd kˈæɹi ˌɔn jʊɹ pˈɜːsən.
OPIE implements a one-time password (OTP) scheme based on S/KEY, which will require a secret passphrase (not echoed) to generate a password for the current session, or a list of passwords you can print and carry on your person.