SC Communication

Introduction

• The following information was reverse engineered from lv0ldr, lv0, lv1, and sc_iso.self.
• Big thanks to graf_chokolo for a large part of the basis of this page, and to Jestero for Syscon Authentication info!

Overview of Syscon Communication

• Syscon lives at the mmio space of 0x24000080000.
• Communication occurs through mmio read/writes.

List of known offsets in Syscon:

Offset (from start of address space)	Size	Description
0xC000	0xFF0	Syscon packet send area
0xCFF0	0x4	Syscon sent packet counter
0xCFF4	0x4	Syscon sent packet acknowledge counter
0xD000	0xFF0	Syscon packet receive area
0xDFF0	0x4	Syscon received packet counter
0xDFF4	0x4	Syscon received packet acknowledge counter
0xE100	0x4	Tells syscon there is a packet to be received

Quick explanation of the packet counters:

• There are two counters that are incremented by each side (Cell / Syscon).
• 0xCFF0 and 0xDFF0 are incremented by the sending side (Syscon for 0xCFF0, Cell for 0xDFF0)
• 0xCFF4 and 0xDFF4 are incremented by the receiving side (Cell for 0xCFF4, Syscon for 0xDFF4)

Syscon Services

• To be completed...

Service ID	Description
0x14	NVS Service - Used for eeprom read/write (Non-Volatile Storage?)
0x18	Livelock(?) Service - Checks for permission to use other services
0x1F	Authenticated Services
0xFF	Syscon Init (Seen in lv0ldr init sequence to syscon: http://www.ps3devwiki.com/wiki/User_talk:JuanNadie)

Syscon Authentication

- An IV of 0x00 is used for most AES steps.

Step 1 - Generate Individual Seeds

Encrypt sc_iso metadata seeds w/ eid root key / iv.

aes256cbc_enc(eid_root_erk, eid_root_riv, sc_module_seeds, 0x40, sc_module_seeds);

Step 2 - Generate SC_ISO encrypted keys

Encrypt the sc_key_seeds.

indiv_key = sc_module_seeds + 0x20;
for (int i = 0; i < 0x100; i += 0x10)
    aes256cbc_enc(indiv_key, zero_iv, key_seeds + i, 0x10, enc_key_seeds + i);

Step 3 - Authenticate with Syscon

Pick a session_id. Must be <= 7.

Step 3a - Secure Packet Header

struct secure_payload_header {
    u8 session_id;
    u8 seq_service_id;  //service_ID (Unsecure uses 0xFF, AUTH1 = 0x02, AUTH2 = 0x03, READ/WRITE = 0x04)
    u8 packet_type;     //0xFF for BE->SC, 0x00 for SC->BE (if success)
    u8 magic[0x2];      //0xAD1A
    u8 prng_random[0xB] //Random shit for padding
};

Step 3b - AUTH 1 to SC

u8 auth1_pkt_header[] = {0x1f,0x01,0x00,0x00,0x00,0x00,0x80,0x20,0x00,0x00,0x00,0x00,0x00,0x30,0x00,0x30};
uint8_t random_shit[0x10];
auth_key_1_0x01 = enc_key_seeds + (session_id * (0x10*2));
auth_key_2_0x01 = enc_key_seeds + (session_id * (0x10*2) + 0x10);

//generating random payload for auth1
rnd_gen(random_shit, 0x10);

//create auth1 random data
aes128cbc_enc(auth_key_1_0x01, zero_iv, random_shit, 0x10, secure_payload_buf + 0x10);

//Create secure header/footer
// create header: 5 bytes + random stuff (0xb)
payload_header->session_id = session_id;
payload_header->seq_service_id = seq_service_id++; // starts at 0
payload_header->packet_type = 0xFF;
payload_header->magic[0] = 0xAD;
payload_header->magic[1] = 0x1A;
rnd_gen((u8*) &payload_header->prng_random, 0x0B);
    
//encrypt payload
aes128cbc_enc(be2sc_key, zero_iv, secure_payload_buf, length, secure_payload_buf);

// create footer: omac1 of the whole packet
aesOmac1Mode(secure_payload_buf + length, secure_payload_buf, length, be2sc_key, sizeof(be2sc_key)*8);

//Set regular header
memcpy(sc_packet, auth1_pkt_header, 0x10);

//Send packet.