> Sifr is also a valid word both in Farsi, I think

That is the root of 'cipher'; meaning zero/empty/nothingness.

Indeed and used cleverly in Casino Royale by naming Le Chiffre that way.

I knew 'sifr' was an Arabic word and only today I came to know that it works in Farsi too.

The double pun/irony is that the John Sipher's surname is related to the topic of cryptography and that the etymological roots is Middle-Eastern.