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Document SSK generation.
The SSK is derived on boot via the SBK, the 32-bit console-unique "Device Key", and hardware information stored in fuses.
The SSK is derived on boot via the SBK, the 32-bit console-unique "Device Key", and hardware information stored in fuses.
Pseudocode for the derivation is as follows:
void generateSSK() {
char keyBuffer[0x10]; // Used to store keydata
uint hwInfoBuffer[4]; // Used to store info about hardware from fuses
uint deviceKey = getDeviceKey(); // Reads 32-bit device key from FUSE_PRIVATE_KEY4.
for (int i = 0; i < 4; i++) { // Keybuffer = deviceKey || deviceKey || deviceKey || deviceKey
((uint *)keyBuffer)[i] = deviceKey;
}
encryptWithSBK(keyBuffer); // keyBuffer = AES-ECB(SBK, deviceKey || {...})
// Set up Hardware info buffer
uint vendor_code = *((uint *)0x7000FA00) & 0x0000000F; // FUSE_VENDOR_CODE
uint fab_code = *((uint *)0x7000FA04) & 0x0000000F; // FUSE_FAB_CODE
uint lot_code_0 = *((uint *)0x7000FA08) & 0xFFFFFFFF; // FUSE_LOT_CODE_0
uint lot_code_1 = *((uint *)0x7000FA0C) & 0x0FFFFFFF; // FUSE_LOT_CODE_1
uint wafer_id = *((uint *)0x7000FA10) & 0x0000003F; // FUSE_WAFER_ID
uint x_coord = *((uint *)0x7000FA14) & 0x000001FF; // FUSE_X_COORDINATE
uint y_coord = *((uint *)0x7000FA18) & 0x000001FF; // FUSE_Y_COORDINATE
uint unk_hw_fuse = *((uint *)0x7000FA20) & 0x0000003F; // Unknown cached fuse.
// HARDWARE_INFO_BUFFER = unk_hw_fuse || Y_COORD || X_COORD || WAFER_ID || LOT_CODE || FAB_CODE || VENDOR_ID
hwInfoBuffer[0] = (lot_code_1 << 30) | (wafer_id << 24) | (x_coord << 15) | (y_coord << 6) | unk_hw_fuse;
hwInfoBuffer[1] = (lot_code_0 << 26) | (lot_code_1 >> 2);
hwInfoBuffer[2] = (fab_code << 26) | (lot_code_0 >> 6);
hwInfoBuffer[3] = vendor_code;
for (int i = 0; i < 0x10; i++) { // keyBuffer = XOR(AES-ECB(SBK, deviceKey || {...}), HARDWARE_INFO_BUFFER)
keyBuffer[i] ^= ((char *)hwInfoBuffer)[i];
}
encryptWithSBK(keyBuffer); // keyBuffer = AES-ECB(SBK, XOR(AES-ECB(SBK, deviceKey || {...}), HARDWARE_INFO_BUFFER))
setKeyslot(KEYSLOT_SSK, keyBuffer); SSK = keyBuffer.
}
== Falcon coprocessor ==
== Falcon coprocessor ==
The falcon processor (TSEC) stores a special console-unique key (that will be referred to as the "tsec key").
The falcon processor (TSEC) stores a special console-unique key (that will be referred to as the "tsec key").