BCAT Content Container
Content downloaded by BCAT normally uses this container.
Header
| Offset | Size | Description |
|---|---|---|
| 0x0 | 0x4 | Magicnum "bcat" |
| 0x4 | 0x1 | ? |
| 0x5 | 0x1 | Crypto type |
| 0x6 | 0x1 | ? |
| 0x7 | 0x1 | Secret-data index |
| 0x8 | 0x8 | Normally zero? |
| 0x10 | 0x10 | Base IV/CTR |
| 0x20 | 0x100 | RSA-2048 signature, presumably. |
The header is 0x120-bytes.
Key generation
The AES keydata is the output from pkcs5_pbkdf2_hmac, with SHA256: password = <passphrase string loaded from file>, salt = <below salt string>, and iteration_count=4096.
The passphrase is loaded from "<basepath>/passphrase.bin". passphrase_len=strlen(passphrase). 0x40-bytes are read from the file, with 0x0 being written to passphrase[total_read_data]. salt_len = strlen(salt).
salt is the snprintf output from "%016llx%s", where the former is presumably the titleID, while the latter is secretdata_str. secretdata_str = secretdata_array[<value of hdr+0x7>].
Settings config for 1-byte <"bcat", "production_mode"> is loaded, when retval!=1 or output_config!=0, then secretdata_array = secretdata_array0(retail), otherwise secretdata_array = secretdata_array1(devunit). The latter only contains empty strings, while the former contains lower-case hex strings. There are 16 entries in each array.