def encryptInCBC(key,data,fileNameToEncrypt):
    data=bytes(data, 'utf-8')
    cipher = AES.new(key, AES.MODE_CBC)
    start = timer()
    ct_bytes = cipher.encrypt(pad(data, AES.block_size))
    end= timer()
    print("Time Taken to Encrypt is "+str(end-start))
    print("Time Taken to Encrypt per byte is ",(end-start)/len(data))
    iv = b64encode(cipher.iv).decode('utf-8')
    ct = b64encode(ct_bytes).decode('utf-8')
    writeFileInBytes(bytes(ct,"utf-8"),fileNameToEncrypt)
    return iv