def t06_PutOffByOneSize(C, pks, crypto, server):
    """Uploads a file with only a few bytes different by changing its
    length."""
    alice = C("alice")
    alice.upload("k", "a" * 10000)
    alice.upload("k", "a" * 10000 + "b")
    score = alice.download("k") == "a" * 10000 + "b"
    alice.upload("k", "a" * 9999 + "b")
    score += alice.download("k") == "a" * 9999 + "b"
    return score / 2.0