7.4.7 Decryption

After writing the full encrypted binary in the program RAM, decryption of the program is launched. There are two options depending on the content of the encrypted program, which has been loaded.

If the KEY_TAG includes only the program, basic decryption is required (CMD=0x0013).

If the KEY_TAG includes the program plus initial vector and total number of packets, decryption plus is required (CMD=0x0015).

In both cases, neither address nor data are considered.

If FORCE_IVNBINC fuse is set to ‘1’, both decryption commands (CMD=0x0013 and CMD=0x0015) will calculate the signature over SOFT+IV+NB.