What is CBC?

When changing the key (click here to learn to change the key), CRFSuite asks if you would like to use CBC encryption mode.

CBC is a powerful mode of using the encryption algorithms. Using AES with CBC data generated looks pseudo-random and cannot be understood without the encryption key. This encryption mode is supported by CRFSuite 3.1 and above. A .CRF file encrypted with CBC mode will not be decoded by previous versions of CRFSuite.

In the example below, we have encrypted a picture using ECB and CBC:

    Tux.jpg Tux ecb.jpg Tux secure.jpg
    Original image Encrypted using old method (ECB mode) Encrypted using new method (CBC mode)

Please note that the data encrypted by the reader is quite small therefore it will not generate a pattern like in the above picture. For this reason is almost impossible to decrypt it without a key even if it is encrypted with old mode (ECB). However it will be even more difficult to crack it with the new encryption mode (CBC).