Gamestats2 encryption

DWCi_EncSessionEncrypt

struct data_info
{
  uint32_le pid;
  uint32_le data_size;
};
DWCi_EncSessionEncrypt(char* dest, struct data_info* info, uint32_t info_size, char* data, uint32_t data_size);

This function is used to encrypt Gamestats2 data payload.

PowerPC assembly code

C++ pseudo code

; 0x80354b04 DWCi_EncSessionEncrypt stwu sp, -0x0030 (sp) mflr r0 stw r0, 0x0034 (sp) addi r11, sp, 48 bl -> _savegpr_23 (0x803F1310) add r30, r7, r5 mr r23, r3 addi r31, r30, 4 mr r24, r4 mr r25, r5 mr r26, r6 mr r27, r7 mr r4, r31 li r28, 0 li r3, 8 bl -> DWC_Alloc (0x80335390) cmpwi r3, 0 mr r29, r3 bne- ->0x80354B58 li r3, 2 b ->0x803550D8 cmpwi cr1, r25, 0 li r4, 0 ble- cr1 ->0x80354C24 cmpwi r25, 8 subi r6, r25, 8 ble- ->0x80354BF8 li r7, 0 blt- cr1 ->0x80354B8C lis r5, 0x8000 subi r0, r5, 2 cmpw r25, r0 bgt- ->0x80354B8C li r7, 1 cmpwi r7, 0 beq- ->0x80354BF8 addi r0, r6, 7 rlwinm r0, r0, 29, 3, 31 (fffffff8) mtctr r0 cmpwi r6, 0 ble- ->0x80354BF8 lbzx r5, r24, r4 add r6, r24, r4 add r7, r3, r4 lbz r0, 0x0001 (r6) stb r5, 0x0004 (r7) addi r4, r4, 8 lbz r5, 0x0002 (r6) stb r0, 0x0005 (r7) lbz r0, 0x0003 (r6) stb r5, 0x0006 (r7) lbz r5, 0x0004 (r6) stb r0, 0x0007 (r7) lbz r0, 0x0005 (r6) stb r5, 0x0008 (r7) lbz r5, 0x0006 (r6) stb r0, 0x0009 (r7) lbz r0, 0x0007 (r6) stb r5, 0x000A (r7) stb r0, 0x000B (r7) bdnz+ ->0x80354BA8 sub r0, r25, r4 add r5, r24, r4 mtctr r0 cmpw r4, r25 bge- ->0x80354C24 lbz r0, 0 (r5) add r6, r3, r4 addi r4, r4, 1 addi r5, r5, 1 stb r0, 0x0004 (r6) bdnz+ ->0x80354C0C cmpwi cr1, r27, 0 li r4, 0 ble- cr1 ->0x80354CF8 cmpwi r27, 8 subi r6, r27, 8 ble- ->0x80354CC8 li r7, 0 blt- cr1 ->0x80354C58 lis r5, 0x8000 subi r0, r5, 2 cmpw r27, r0 bgt- ->0x80354C58 li r7, 1 cmpwi r7, 0 beq- ->0x80354CC8 addi r0, r6, 7 add r7, r3, r25 rlwinm r0, r0, 29, 3, 31 (fffffff8) mtctr r0 cmpwi r6, 0 ble- ->0x80354CC8 lbzx r5, r26, r4 add r8, r26, r4 add r6, r7, r4 lbz r0, 0x0001 (r8) stb r5, 0x0004 (r6) addi r4, r4, 8 lbz r5, 0x0002 (r8) stb r0, 0x0005 (r6) lbz r0, 0x0003 (r8) stb r5, 0x0006 (r6) lbz r5, 0x0004 (r8) stb r0, 0x0007 (r6) lbz r0, 0x0005 (r8) stb r5, 0x0008 (r6) lbz r5, 0x0006 (r8) stb r0, 0x0009 (r6) lbz r0, 0x0007 (r8) stb r5, 0x000A (r6) stb r0, 0x000B (r6) bdnz+ ->0x80354C78 sub r0, r27, r4 add r7, r3, r25 add r5, r26, r4 mtctr r0 cmpw r4, r27 bge- ->0x80354CF8 lbz r0, 0 (r5) add r6, r7, r4 addi r4, r4, 1 addi r5, r5, 1 stb r0, 0x0004 (r6) bdnz+ ->0x80354CE0 cmpwi cr1, r30, 0 li r7, 0 ble- cr1 ->0x80354DB8 cmpwi r30, 8 subi r5, r30, 8 ble- ->0x80354D94 li r6, 0 blt- cr1 ->0x80354D2C lis r4, 0x8000 subi r0, r4, 2 cmpw r30, r0 bgt- ->0x80354D2C li r6, 1 cmpwi r6, 0 beq- ->0x80354D94 addi r0, r5, 7 rlwinm r0, r0, 29, 3, 31 (fffffff8) mtctr r0 cmpwi r5, 0 ble- ->0x80354D94 add r5, r3, r7 addi r7, r7, 8 lbz r4, 0x0004 (r5) lbz r0, 0x0005 (r5) add r28, r28, r4 lbz r4, 0x0006 (r5) add r28, r28, r0 lbz r0, 0x0007 (r5) add r28, r28, r4 lbz r4, 0x0008 (r5) add r28, r28, r0 lbz r0, 0x0009 (r5) add r28, r28, r4 lbz r4, 0x000A (r5) add r28, r28, r0 lbz r0, 0x000B (r5) add r28, r28, r4 add r28, r28, r0 bdnz+ ->0x80354D48 sub r0, r30, r7 mtctr r0 cmpw r7, r30 bge- ->0x80354DB8 add r4, r3, r7 addi r7, r7, 1 lbz r0, 0x0004 (r4) add r28, r28, r0 bdnz+ ->0x80354DA4 rlwinm r0, r28, 16, 0, 15 (0000ffff) cmpwi cr1, r30, 0 or r0, r28, r0 li r6, 0 stw r0, -0x343C (r13) ble- cr1 ->0x80355044 cmpwi r30, 8 subi r5, r30, 8 ble- ->0x80354FE8 li r7, 0 blt- cr1 ->0x80354DF8 lis r4, 0x8000 subi r0, r4, 2 cmpw r30, r0 bgt- ->0x80354DF8 li r7, 1 cmpwi r7, 0 beq- ->0x80354FE8 addi r0, r5, 7 lis r4, 0x8049 rlwinm r0, r0, 29, 3, 31 (fffffff8) subi r4, r4, 9208 mtctr r0 cmpwi r5, 0 ble- ->0x80354FE8 ; Load key constant X lwz r7, 0x0044 (r4) add r5, r3, r6 ; Load seed lwz r0, -0x343C (r13) ; Load key constant Y lwz r8, 0x0048 (r4) mullw r0, r7, r0 ; Load key constant Z lwz r7, 0x004C (r4) add r8, r8, r0 divwu r0, r8, r7 mullw r0, r0, r7 sub r0, r8, r0 ; Store seed stw r0, -0x343C (r13) rlwinm r7, r0, 16, 24, 31 (00ff0000) ; XOR data lbz r0, 0x0004 (r5) xor r0, r0, r7 stb r0, 0x0004 (r5) ; Keep going (x2) - Load key constant X lwz r7, 0x0044 (r4) lwz r0, -0x343C (r13) lwz r8, 0x0048 (r4) mullw r0, r7, r0 lwz r7, 0x004C (r4) add r8, r8, r0 divwu r0, r8, r7 mullw r0, r0, r7 sub r0, r8, r0 stw r0, -0x343C (r13) rlwinm r7, r0, 16, 24, 31 (00ff0000) lbz r0, 0x0005 (r5) xor r0, r0, r7 stb r0, 0x0005 (r5) ; Keep going (x3) - Load key constant X lwz r7, 0x0044 (r4) lwz r0, -0x343C (r13) lwz r8, 0x0048 (r4) mullw r0, r7, r0 lwz r7, 0x004C (r4) add r8, r8, r0 divwu r0, r8, r7 mullw r0, r0, r7 sub r0, r8, r0 stw r0, -0x343C (r13) rlwinm r7, r0, 16, 24, 31 (00ff0000) lbz r0, 0x0006 (r5) xor r0, r0, r7 stb r0, 0x0006 (r5) ; Keep going (x4) - Load key constant X lwz r7, 0x0044 (r4) lwz r0, -0x343C (r13) lwz r8, 0x0048 (r4) mullw r0, r7, r0 lwz r7, 0x004C (r4) add r8, r8, r0 divwu r0, r8, r7 mullw r0, r0, r7 sub r0, r8, r0 stw r0, -0x343C (r13) rlwinm r7, r0, 16, 24, 31 (00ff0000) lbz r0, 0x0007 (r5) xor r0, r0, r7 stb r0, 0x0007 (r5) ; Keep going (x5) - Load key constant X lwz r7, 0x0044 (r4) lwz r0, -0x343C (r13) lwz r8, 0x0048 (r4) mullw r0, r7, r0 lwz r7, 0x004C (r4) add r8, r8, r0 divwu r0, r8, r7 mullw r0, r0, r7 sub r7, r8, r0 stw r7, -0x343C (r13) lbz r0, 0x0008 (r5) rlwinm r7, r7, 16, 24, 31 (00ff0000) addi r6, r6, 8 xor r0, r0, r7 stb r0, 0x0008 (r5) ; Keep going (x6) - Load key constant X lwz r7, 0x0044 (r4) lwz r0, -0x343C (r13) lwz r8, 0x0048 (r4) mullw r0, r7, r0 lwz r7, 0x004C (r4) add r8, r8, r0 divwu r0, r8, r7 mullw r0, r0, r7 sub r0, r8, r0 stw r0, -0x343C (r13) rlwinm r7, r0, 16, 24, 31 (00ff0000) lbz r0, 0x0009 (r5) xor r0, r0, r7 stb r0, 0x0009 (r5) ; Keep going (x7) - Load key constant X lwz r7, 0x0044 (r4) lwz r0, -0x343C (r13) lwz r8, 0x0048 (r4) mullw r0, r7, r0 lwz r7, 0x004C (r4) add r8, r8, r0 divwu r0, r8, r7 mullw r0, r0, r7 sub r0, r8, r0 stw r0, -0x343C (r13) rlwinm r7, r0, 16, 24, 31 (00ff0000) lbz r0, 0x000A (r5) xor r0, r0, r7 stb r0, 0x000A (r5) ; Keep going (x8) - Load key constant X lwz r7, 0x0044 (r4) lwz r0, -0x343C (r13) lwz r8, 0x0048 (r4) mullw r0, r7, r0 lwz r7, 0x004C (r4) add r8, r8, r0 divwu r0, r8, r7 mullw r0, r0, r7 sub r0, r8, r0 stw r0, -0x343C (r13) rlwinm r0, r0, 16, 24, 31 (00ff0000) lbz r7, 0x000B (r5) xor r0, r7, r0 stb r0, 0x000B (r5) bdnz+ ->0x80354E1C lis r8, 0x8049 sub r0, r30, r6 subi r8, r8, 9208 mtctr r0 cmpw r6, r30 bge- ->0x80355044 ; Keep going (last ones) - Load key constant X lwz r4, 0x0044 (r8) add r5, r3, r6 lwz r0, -0x343C (r13) addi r6, r6, 1 lwz r7, 0x0048 (r8) mullw r0, r4, r0 lwz r4, 0x004C (r8) add r7, r7, r0 divwu r0, r7, r4 mullw r0, r0, r4 sub r0, r7, r0 stw r0, -0x343C (r13) rlwinm r0, r0, 16, 24, 31 (00ff0000) lbz r4, 0x0004 (r5) xor r0, r4, r0 stb r0, 0x0004 (r5) bdnz+ ->0x80355000 lis r5, 0x8049 addi r24, r30, 4 subi r5, r5, 9208 mr r4, r23 lwz r0, 0x0050 (r5) mr r5, r24 li r6, 2 xor r28, r28, r0 rlwinm r0, r28, 8, 24, 31 (ff000000) ; Store encoded checksum stb r0, 0 (r3) rlwinm r7, r28, 16, 24, 31 (00ff0000) rlwinm r0, r28, 24, 24, 31 (0000ff00) stb r7, 0x0001 (r3) stb r0, 0x0002 (r3) stb r28, 0x0003 (r3) mr r3, r29 bl -> B64Encode (0x8035DAA4) mr r4, r29 li r3, 8 li r5, 0 bl -> DWC_Free (0x80335450) lis r3, 0xAAAB li r6, 0 subi r4, r3, 21845 mulhwu r0, r4, r24 li r3, 0 mulhwu r4, r4, r31 rlwinm r0, r0, 31, 1, 31 (fffffffe) mulli r0, r0, 3 rlwinm r5, r4, 31, 1, 31 (fffffffe) sub r4, r24, r0 neg r0, r4 or r0, r0, r4 rlwinm r0, r0, 1, 31, 31 (80000000) add r0, r5, r0 rlwinm r4, r0, 2, 0, 29 (3fffffff) stbx r6, r4, r23 addi r11, sp, 48 bl -> _restgpr_23 (0x803F135C) lwz r0, 0x0034 (sp) mtlr r0 addi sp, sp, 48 blr

int DWCi_EncSessionEncrypt( char* dest, struct data_info* info, uint32_t info_size, char* data, uint32_t data_size ) { _savegpr_23(...); uint32_t total_size = 4 + info_size + data_size; void* ptr = DWC_Alloc(8, total_size); if (ptr == nullptr) goto label_exit; // TODO label_exit: DWC_Free(8, ptr, 0); _restgpr_23(...); }