Difference between revisions of "BCAT Content Container"
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| 0x4 | | 0x4 | ||
| 0x1 | | 0x1 | ||
| − | | ? | + | | ? Required to be 1. |
|- | |- | ||
| 0x5 | | 0x5 | ||
| Line 22: | Line 22: | ||
| 0x6 | | 0x6 | ||
| 0x1 | | 0x1 | ||
| − | | RSA/Hash Type: {0x0,0x2} = SHA1, {0x1,0x3} = SHA256. The former value in each pair is RSA PKCS1. Value >0x3 eventually results in an error being thrown. | + | | RSA/Hash Type: {0x0,0x2} = SHA1, {0x1,0x3} = SHA256. The former value in each pair is RSA PKCS1, while the later value in each pair is RSA PSS. Value >0x3 eventually results in an error being thrown. |
|- | |- | ||
| 0x7 | | 0x7 | ||
| Line 42: | Line 42: | ||
The header is 0x120-bytes. | The header is 0x120-bytes. | ||
| + | |||
| + | Settings config for 1-byte <"bcat", "production_mode"> is loaded, the output is used to determine which RSA modulo and secret data array to use. | ||
=Key generation= | =Key generation= | ||
Latest revision as of 16:28, 18 November 2020
Content downloaded by BCAT normally uses this container.
Header
| Offset | Size | Description |
|---|---|---|
| 0x0 | 0x4 | Magicnum "bcat" |
| 0x4 | 0x1 | ? Required to be 1. |
| 0x5 | 0x1 | Crypto type: 0x1 = AES-128-CTR, 0x2 = AES-192-CTR, 0x3 = AES-256-CTR. Everything else indicates plaintext. |
| 0x6 | 0x1 | RSA/Hash Type: {0x0,0x2} = SHA1, {0x1,0x3} = SHA256. The former value in each pair is RSA PKCS1, while the later value in each pair is RSA PSS. Value >0x3 eventually results in an error being thrown. |
| 0x7 | 0x1 | Secret-data index |
| 0x8 | 0x8 | Normally zero? |
| 0x10 | 0x10 | Base IV/CTR |
| 0x20 | 0x100 | RSA-2048 signature |
The header is 0x120-bytes.
Settings config for 1-byte <"bcat", "production_mode"> is loaded, the output is used to determine which RSA modulo and secret data array to use.
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" (this data originally comes from the title's control.nacp @ 0x3100). 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 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.