A method, comprising: - receiving over an AXI bus data access requests for data units stored in a memory, wherein the AXI bus operates in burst mode, wherein the requests comprise burst requests for access to respective sets of data units stored in the memory starting from respective data start addresses, the burst requests conveying said respective data start addresses, security information indicative of whether the data units requested in the burst requests are encrypted or non-encrypted data units, and supplemental information on data unit size, burst request type and burst request lengths; - reading the data start addresses and the security information conveyed by the burst requests, thereby subdividing the burst requests received, as a function of said data start addresses and said security information, into burst requests for encrypted data units and burst requests for non-encrypted data units, wherein both burst requests for encrypted data units and burst requests for non-encrypted data units are forwarded towards the memory and the respective sets of data units are retrieved from the memory over the AXI bus; wherein Advanced Encryption Standard, AES, processing (60, 70, 80) is applied to the burst requests for encrypted data units by calculating decryption masks for the encrypted data units and applying the decryption masks calculated to the encrypted data units retrieved, wherein the method comprises: - receiving data unit availability signals indicative of availability of data units from the memory, - applying said calculated decryption masks to encrypted data units out of data units available from the memory by: - calculating, as a function of said data unit availability signals and said supplemental information, current data addresses for said encrypted data units, - selecting (86, 88) the decryption masks applied to said encrypted data units as a function of the current data addresses thereof. - receiving over an AXI bus data access requests for data units stored in a memory, wherein the AXI bus operates in burst mode, wherein the requests comprise burst requests for access to respective sets of data units stored in the memory starting from respective data start addresses, the burst requests conveying said respective data start addresses, security information indicative of whether the data units requested in the burst requests are encrypted or non-encrypted data units, and supplemental information on data unit size, burst request type and burst request lengths; - reading the data start addresses and the security information conveyed by the burst requests, thereby subdividing the burst requests received, as a function of said data start addresses and said security information, into burst requests for encrypted data units and burst requests for non-encrypted data units, wherein both burst requests for encrypted data units and burst requests for non-encrypted data units are forwarded towards the memory and the respective sets of data units are retrieved from the memory over the AXI bus; - receiving data unit availability signals indicative of availability of data units from the memory, - applying said calculated decryption masks to encrypted data units out of data units available from the memory by: - calculating, as a function of said data unit availability signals and said supplemental information, current data addresses for said encrypted data units, - selecting (86, 88) the decryption masks applied to said encrypted data units as a function of the current data addresses thereof. - calculating, as a function of said data unit availability signals and said supplemental information, current data addresses for said encrypted data units, - selecting (86, 88) the decryption masks applied to said encrypted data units as a function of the current data addresses thereof.