Читать книгу Security Engineering - Ross Anderson - Страница 170

A common failure is that cryptographic libraries enable or even encourage developers to use an inappropriate mode of operation. This specifies how a block cipher with a fixed block size (8 bytes for DES, 16 for AES) can be extended to process messages of arbitrary length.

There are several standard modes of operation for using a block cipher on multiple blocks [1406]. It is vital to understand them, so you can choose the right one for the job, especially as some common tools provide a weak one by default. This weak mode is electronic code book (ECB) mode, which we discuss next.