def sign(private_key,fileName):
    data=getData(fileName)
    data=data.encode("utf-8")
    start=timer()
    signature = private_key.sign(data,hashes.SHA256())
    end=timer()
    print("Time Taken to generate signature is ",(end-start))
    print("Time Taken per byte to sign is ",((end-start)/len(data)))
    return signature