No, Bloch did not compose Kol Nidre; the prayer chanted at the start of Yom Kippur.
Kol Nidre is already mentioned by the early Talmudic commentators (e.g. the Ran on tractate Nedarim folio 22), making it over 1,000 years old.
Read all about it on http://www.answers.com/topic/kol-nidre
The classical tune is also very old.
However one particular melody, called Kol Nidre, Op. 47, is a composition for cello and orchestra written by Max Bruch. See http://www.answers.com/topic/kol-nidre-bruch and http://www.answers.com/topic/kol-nidre-traditional-ashkenazic for details.