58.4.6.1 Description

The Automatic Bridge mode, when the AESB block is connected between the system bus and a DDR port and the QSPI, provides automatic encryption/decryption without any action on the part of the user. For Automatic Bridge mode, AESB_MR.OPMOD must be configured to 0x4 (see AESB Mode Register). If AESB_MR.AAHB is set and AESB_MR.OPMOD = 0x4, there is no compliance with the standard CTR mode of operation.

In case of write transfer, this mode automatically encrypts the data before writing it to the final client destination. In case of read transfer, this mode automatically decrypts the data read from the target client before putting it on the system bus.

Therefore, this mode does not work if the automatically encrypted data is moved at another address outside of the AESB. This means that for a given data, the encrypted value is not the same if written at different addresses.