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boot2: derive keyY as twl boot9 does, add support for ntrboot images #21

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boot2: derive keyY as twl boot9 does, add support for ntrboot images #21

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11 changes: 11 additions & 0 deletions dsi.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,8 @@
#include <stdlib.h>
#include <time.h>

#include "polarssl/rsa.h"

void dsi_set_key( dsi_context* ctx,
unsigned char key[16] )
{
Expand Down Expand Up @@ -371,3 +373,12 @@ void dsi_es_encrypt( dsi_es_context* ctx,
memcpy(metablock, mac, 16);

}

void dsi_rsa_signature_decrypt(const char * modulus, const unsigned char* signature, unsigned char* message) {
rsa_context rsa;
rsa_init(&rsa, RSA_PKCS_V15, 0);
rsa.len = 128;
mpi_read_string(&rsa.N, 16, modulus);
mpi_read_string(&rsa.E, 16, "10001");
rsa_public(&rsa, signature, message);
}
2 changes: 2 additions & 0 deletions dsi.h
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Original file line number Diff line number Diff line change
Expand Up @@ -97,6 +97,8 @@ void dsi_es_encrypt( dsi_es_context* ctx,
unsigned char metablock[32],
unsigned int size );

void dsi_rsa_signature_decrypt(const char * modulus, const unsigned char* signature, unsigned char* message);

#ifdef __cplusplus
}
#endif
Expand Down
79 changes: 67 additions & 12 deletions main.c
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Expand Up @@ -18,6 +18,15 @@ u32 emmc_keyY[4] = {0x0AB9DC76,0xBD4DC4D3,0x202DDD1D,0xE1A00005};
u8 block[0x10];
int i;

static const char*
s_PubkeyNtrboot =
"cc987b417d9d7c800285db10998cd4a7867aefda43a96d0b55b010736799c2d9f072d6fb1da6179a778987e7e8c8c08636bf5d2cd75a1feae04f66c783a833f493739e3a9770525e3d9d0eed504fd65fc4367191c41681cacf924ead1c3270dc58e58989a36a094390f3f18e404fb7f1687f30f76d008a9cd487254a98c9662f"
, * s_PubkeyNand =
"f1f51aff66f9b3694dcb78deaf311b783c072aac943011114a1cf6fe62b091b5ef0eba3aa9ec3ea01c5df666653e18df22533bd5e8d6ff58970b24e886fa878b62669924a8fa87f274004fea2ff623e1f2907ca4671fca283e86b6cac546a79c75c80feb32882c3d1df7d5dc1a1998e9f626d4fc76cb231358cb43a9b3cba3c5"
, * s_PubkeySpi =
"b85f0fdb262c1afcf86e37a7cdd211d455203ca8fb106edec7036ed7d6363b6633f4d6275865b632b9277a74ce1d41dbd96a0486ee7271b38673a03b8348627b22a20b7738dd027376c4f8523dea5c6f5df262e45f7a901c16a18cff0588862e1c826276c8ac7987f0a1d57d9399d5cd5d48554d30315dc1b15a324511f911cb"
;

typedef struct __attribute__((__packed__))
{
u8 status;
Expand Down Expand Up @@ -127,7 +136,7 @@ int decryptsrl(u8 *srl)
return 0;
}

void decrypt_boot2_section(u8* data, u32 len, bool is3DS)
void decrypt_boot2_section(u8* data, u32 len, bool is3DS, bool isNtrboot, u8* keyY)
{
u8 normalkey[16] = {0};
u8 keyX_TWLFIRM[16] = {0xE1, 0xEB, 0xDF, 0x44, 0xAB, 0x1D, 0x81, 0xE3, 0x93, 0x9A, 0x4A, 0xB5, 0x36, 0xFC, 0x3A, 0x0E};
Expand All @@ -140,6 +149,8 @@ void decrypt_boot2_section(u8* data, u32 len, bool is3DS)
int i;

dsi_context dsictx;
if (keyY != NULL) memcpy(keyY_DSi, keyY, 16);

if(is3DS == true)
F_XY((u32*) normalkey, (u32*)keyX_TWLFIRM, (u32*)keyY_3DS);
else
Expand All @@ -161,45 +172,85 @@ void decrypt_boot2_section(u8* data, u32 len, bool is3DS)
dsi_crypt_ctr_block(&dsictx, data+i, data+i);
}

void decrypt_boot2(char* in, bool is3DS)
void decrypt_boot2(char* in, bool is3DS, bool isNtrboot)
{
u32 offset;
u32 len;
u8* data;
FILE* f_in = fopen(in,"r+b");
//u8 signedData[
FILE* f_in = fopen(in,"rb");
FILE* f_out;
u32 arm9_offset = isNtrboot ? 0x20 : 0x220;
u32 arm7_offset = isNtrboot ? 0x30 : 0x230;
if(f_in == NULL)
{
printf("Input filename invalid!");
printf("Input filename invalid!\n");
return;
}

// get the keyY from the signature
u8 signature[0x80];
u8 message[0x80];
const char* pubkey = NULL;
u8* keyY = NULL;
if (!is3DS) {
static const u8 s_MessagePadding[] = { 0, 1, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0 };
if (isNtrboot) {
pubkey = s_PubkeyNtrboot;
fseek(f_in, 0x100, SEEK_SET);
fread(signature, 1, sizeof(signature), f_in);
dsi_rsa_signature_decrypt(pubkey, signature, message);
if (memcmp(message, s_MessagePadding, sizeof(s_MessagePadding)) != 0) {
printf("Signature invalid!\n");
return;
}
} else {
pubkey = s_PubkeyNand;
fseek(f_in, 0x300, SEEK_SET);
fread(signature, 1, sizeof(signature), f_in);
dsi_rsa_signature_decrypt(pubkey, signature, message);
if (memcmp(message, s_MessagePadding, sizeof(s_MessagePadding)) != 0) {
pubkey = s_PubkeySpi;
dsi_rsa_signature_decrypt(pubkey, signature, message);
if (memcmp(message, s_MessagePadding, sizeof(s_MessagePadding)) != 0) {
printf("Signature invalid!\n");
return;
}
}
}
keyY = &message[sizeof(s_MessagePadding)];
printf("KeyY:\n");
hexdump(keyY,16);
}

// decrypt and write ARM9
f_out = fopen("arm9.bin","wb");
fseek(f_in, 0x220, SEEK_SET);
fseek(f_in, arm9_offset, SEEK_SET);
fread(&offset, 1, sizeof(offset), f_in);
fseek(f_in, 0x22C, SEEK_SET);
fseek(f_in, arm9_offset + 0xC, SEEK_SET);
fread(&len, 1, sizeof(len), f_in);
printf("arm9: offset=%x, len=%x\n", offset, len);

fseek(f_in, offset, SEEK_SET);
data = malloc(len);
fread(data, 1, len, f_in);
decrypt_boot2_section(data, len, is3DS);
decrypt_boot2_section(data, len, is3DS, isNtrboot, keyY);
fwrite(data, 1, len, f_out);
free(data);
fclose(f_out);

// decrypt and write ARM7
f_out = fopen("arm7.bin","wb");
fseek(f_in, 0x230, SEEK_SET);
fseek(f_in, arm7_offset, SEEK_SET);
fread(&offset, 1, sizeof(offset), f_in);
fseek(f_in, 0x23C, SEEK_SET);
fseek(f_in, arm7_offset + 0xC, SEEK_SET);
fread(&len, 1, sizeof(len), f_in);
printf("arm7: offset=%x, len=%x\n", offset, len);

fseek(f_in, offset, SEEK_SET);
data = malloc(len);
fread(data, 1, len, f_in);
decrypt_boot2_section(data, len, is3DS);
decrypt_boot2_section(data, len, is3DS, isNtrboot, keyY);
fwrite(data, 1, len, f_out);
fclose(f_out);
fclose(f_in);
Expand Down Expand Up @@ -720,6 +771,7 @@ void display_help()
printf("boot2: decrypt boot2 image to arm7.bin and arm9.bin\n");
printf(" --in [infile] Input image\n");
printf(" --debug Crypt debug boot2 (devkits, TWL_FIRM, ...)\n");
printf(" --ntrboot Crypt ntrboot image\n");
printf("syscrypt: crypt system files with ES block crypto (dev.kp, tickets, ...)\n");
printf(" --in [infile] Input SRL\n");
printf(" --out [outfile] Output file (optional)\n");
Expand All @@ -737,7 +789,7 @@ int main(int argc, char* argv[])
char in[400] = {0};
char out[400] = {0};
char cidfile[400] = {0};
bool is3DS = false;
bool is3DS = false, isNtrboot = false;
bool brute_cid = false;
bool isN3DS = false;
bool encrypt = false;
Expand Down Expand Up @@ -835,13 +887,16 @@ int main(int argc, char* argv[])
if(!strcmp(argv[i],"--debug")) {
is3DS = 1;
}
if(!strcmp(argv[i],"--ntrboot")) {
isNtrboot = 1;
}
}
if(in[0] == 0) {
printf("Invalid filename!\n");
display_help();
exit(EXIT_FAILURE);
}
decrypt_boot2(in, is3DS);
decrypt_boot2(in, is3DS, isNtrboot);
}
else if(!strcmp(argv[1], "syscrypt"))
{
Expand Down