Stefan Claas in sci.crypt:

>echo -n 'Merry Christmas and a Happy New Year' | base16 -l 0
>4d65727279204368726973746d617320616e642061204861707079204e65772059656172
>
>Now we encrypt this message with fpe, a 256 bit key and a 64 bit nonce:
>
>ca94a7a70929a2eb44faf7a9195541be16a97ab17e0a40cd95c81978f14fcdf6b76892ae
>
>After that we convert the hex string to decimal
>
>393547191367737629111313439284388256222575714261460221423875982235587707334230765245102

If the FPE ciphertext (accidentally) begins with "00" then there
is a problem to decode the decimal value back to hex, I think:

| user15@o15:/tmp$ BC_LINE_LENGTH=0 bc -q
| ibase=16
| 0094A7A70929A2EB44FAF7A9195541BE16A97AB17E0A40CD95C81978F14FCDF6B76892AE
| 1128075138140356785582134106037437080809532772928038131009875468329041722778648613550

| user15@o15:/tmp$ BC_LINE_LENGTH=0 bc -q
| obase=16
| 1128075138140356785582134106037437080809532772928038131009875468329041722778648613550
| 94A7A70929A2EB44FAF7A9195541BE16A97AB17E0A40CD95C81978F14FCDF6B76892AE

>Merry Christmas

Thanks. Same to you.

Marcel