Having some fun with Python Generators...

generators.py

def fibonacci(a=0, b=1):
    yield a
    yield b
    while True:
        a = a+b
        yield a
        b = b+a
        yield b


def fibo_hash(m, a=0, b=1):
    for f in fibonacci(a=a, b=b):
        if f.bit_length() >= m:
            return '%x' % f