Enable optional signature verification for NCCH & NCSD

arm9/source/game/ncch.c

@@ -2,6 +2,8 @@
 #include "keydb.h"
 #include "aes.h"
 #include "sha.h"
+#include "rsa.h"
+#include "itcm.h"
 
 #define EXEFS_KEYID(name) (((strncmp(name, "banner", 8) == 0) || (strncmp(name, "icon", 8) == 0)) ? 0 : 1)
 
@@ -28,6 +30,26 @@ u32 ValidateNcchHeader(NcchHeader* header) {
     return 0;
 }
 
+u32 ValidateNcchSignature(NcchHeader* header, NcchExtHeader* exthdr)
+{
+    u8 exp[4] = { 0x00, 0x01, 0x00, 0x01 };
+    u8* pubkey = ARM9_ITCM->rsaModulusCartNCSD;
+
+    if (exthdr) {
+        // check extheader signature
+        if (!RSA_setKey2048(3, (const u32*)(const void*)ARM9_ITCM->rsaModulusAccessDesc, getle32(exp)) ||
+            !RSA_verify2048((const u32*)(const void*)&exthdr->signature[0], (const u32*)(const void*)&exthdr->public_key[0], 0x300))
+            return 1;
+        pubkey = exthdr->public_key;
+    }
+
+    // check NCCH header signature
+    if (!RSA_setKey2048(3, (const u32*)(const void*)&pubkey[0], getle32(exp)) ||
+        !RSA_verify2048((const u32*)(const void*)&header->signature[0], (const u32*)(const void*)&((u8*)header)[0x100], 0x100))
+        return 1;
+    return 0;
+}
+
 u32 GetNcchCtr(u8* ctr, NcchHeader* ncch, u8 section) {
     memset(ctr, 0x00, 16);
     if (ncch->version == 1) {

arm9/source/game/ncch.h

@@ -84,6 +84,7 @@ typedef struct {
 } __attribute__((packed, aligned(16))) NcchHeader;
 
 u32 ValidateNcchHeader(NcchHeader* header);
+u32 ValidateNcchSignature(NcchHeader* header, NcchExtHeader* exthdr);
 u32 SetNcchKey(NcchHeader* ncch, u16 crypto, u32 keyid);
 u32 SetupNcchCrypto(NcchHeader* ncch, u16 crypt_to);
 u32 CryptNcch(void* data, u32 offset, u32 size, NcchHeader* ncch, ExeFsHeader* exefs, u16 crypto);

arm9/source/game/ncsd.c

@@ -1,5 +1,7 @@
 #include "ncsd.h"
 #include "ncch.h"
+#include "rsa.h"
+#include "itcm.h"
 
 u32 ValidateNcsdHeader(NcsdHeader* header) {
     static const u8 zeroes[16] = { 0 };
@@ -22,6 +24,15 @@ u32 ValidateNcsdHeader(NcsdHeader* header) {
     return 0;
 }
 
+u32 ValidateNcsdSignature(NcsdHeader* header) {
+    u8 exp[4] = { 0x00, 0x01, 0x00, 0x01 };
+    // this will fail for non-cart NCSDs anyways, so we don't need to check
+    if (!RSA_setKey2048(3, (const u32*)(const void*)&ARM9_ITCM->rsaModulusCartNCSD[0], getle32(exp)) ||
+        !RSA_verify2048((const u32*)(const void*)&header->signature[0], (const u32*)(const void*)&((u8*)header)[0x100], 0x100))
+        return 1;
+    return 0;
+}
+
 u64 GetNcsdTrimmedSize(NcsdHeader* header) {
     u32 data_units = 0;
     for (u32 i = 0; i < 8; i++) {

arm9/source/game/ncsd.h

@@ -37,5 +37,6 @@ typedef struct {
 } PACKED_STRUCT NcsdHeader;
 
 u32 ValidateNcsdHeader(NcsdHeader* header);
+u32 ValidateNcsdSignature(NcsdHeader* header);
 u64 GetNcsdTrimmedSize(NcsdHeader* header);
 u32 CryptNcsdSequential(void* data, u32 offset_data, u32 size_data, u16 crypto);

arm9/source/godmode.c

@@ -1744,7 +1744,7 @@ u32 FileHandlerMenu(char* current_path, u32* cursor, u32* scroll, PaneData** pan
                 ShowPrompt(false, STR_PATH_TYPE_BUILD_FAILED, pathstr, type);
                 if ((filetype & (GAME_NCCH|GAME_NCSD)) &&
                     ShowPrompt(true, "%s\n%s", pathstr, STR_FILE_FAILED_CONVERSION_VERIFY_NOW)) {
-                    ShowPrompt(false, "%s\n%s", pathstr, (VerifyGameFile(file_path) == 0) ? STR_VERIFICATION_SUCCESS : STR_VERIFICATION_FAILED);
+                    ShowPrompt(false, "%s\n%s", pathstr, (VerifyGameFile(file_path, false) == 0) ? STR_VERIFICATION_SUCCESS : STR_VERIFICATION_FAILED);
                 }
             }
         }
@@ -1797,7 +1797,7 @@ u32 FileHandlerMenu(char* current_path, u32* cursor, u32* scroll, PaneData** pan
             ShowPrompt(false, "%s\n%s", pathstr, (ret == 0) ? STR_INSTALL_SUCCESS : STR_INSTALL_FAILED);
             if ((ret != 0) && (filetype & (GAME_NCCH|GAME_NCSD)) &&
                 ShowPrompt(true, "%s\n%s", pathstr, STR_FILE_FAILED_INSTALL_VERIFY_NOW)) {
-                ShowPrompt(false, "%s\n%s", pathstr, (VerifyGameFile(file_path) == 0) ? STR_VERIFICATION_SUCCESS : STR_VERIFICATION_FAILED);
+                ShowPrompt(false, "%s\n%s", pathstr, (VerifyGameFile(file_path, false) == 0) ? STR_VERIFICATION_SUCCESS : STR_VERIFICATION_FAILED);
             }
         }
         return 0;
@@ -1841,10 +1841,24 @@ u32 FileHandlerMenu(char* current_path, u32* cursor, u32* scroll, PaneData** pan
         return 0;
     }
     else if (user_select == verify) { // -> verify game / nand file
-        if ((n_marked > 1) && ShowPrompt(true, STR_TRY_TO_VERIFY_N_SELECTED_FILES, n_marked)) {
+        bool sig_check = false;
+
+        // check signatures?
+        if (filetype & (GAME_NCSD|GAME_NCCH)) {
+            optionstr[0] = STR_IGNORE_SIGNATURES;
+            optionstr[1] = STR_VERIFY_SIGNATURES;
+            user_select = ShowSelectPrompt(2, optionstr, "%s", STR_USE_SIGNATURE_VERIFICATION);
+            if (!user_select) return 1;
+            sig_check = (user_select == 2);
+        }
+
+        // file verification
+        if (n_marked > 1) {
             u32 n_success = 0;
             u32 n_other = 0;
             u32 n_processed = 0;
+            if (!ShowPrompt(true, STR_TRY_TO_VERIFY_N_SELECTED_FILES, n_marked)) // confirmation
+                return 1;
             for (u32 i = 0; i < current_dir->n_entries; i++) {
                 const char* path = current_dir->entry[i].path;
                 if (!current_dir->entry[i].marked)
@@ -1857,7 +1871,7 @@ u32 FileHandlerMenu(char* current_path, u32* cursor, u32* scroll, PaneData** pan
                 }
                 DrawDirContents(current_dir, (*cursor = i), scroll);
                 if ((filetype & IMG_NAND) && (ValidateNandDump(path) == 0)) n_success++;
-                else if (VerifyGameFile(path) == 0) n_success++;
+                else if (VerifyGameFile(path, sig_check) == 0) n_success++;
                 else { // on failure: show error, continue
                     char lpathstr[UTF_BUFFER_BYTESIZE(32)];
                     TruncateString(lpathstr, path, 32, 8);
@@ -1876,7 +1890,7 @@ u32 FileHandlerMenu(char* current_path, u32* cursor, u32* scroll, PaneData** pan
             ShowString("%s\n%s", pathstr, STR_VERIFYING_FILE_PLEASE_WAIT);
             if (filetype & IMG_NAND) {
                 ShowPrompt(false, "%s\n%s", pathstr, (ValidateNandDump(file_path) == 0) ? STR_NAND_VALIDATION_SUCCESS : STR_NAND_VALIDATION_FAILED);
-            } else ShowPrompt(false, "%s\n%s", pathstr, (VerifyGameFile(file_path) == 0) ? STR_VERIFICATION_SUCCESS : STR_VERIFICATION_FAILED);
+            } else ShowPrompt(false, "%s\n%s", pathstr, (VerifyGameFile(file_path, sig_check) == 0) ? STR_VERIFICATION_SUCCESS : STR_VERIFICATION_FAILED);
         }
         return 0;
     }

arm9/source/lua/gm9internalfs.c

@@ -624,7 +624,7 @@ static int internalfs_verify(lua_State* L) {
 
     u64 filetype = IdentifyFileType(path);
     if (filetype & IMG_NAND) res = (ValidateNandDump(path) == 0);
-    else res = (VerifyGameFile(path) == 0);
+    else res = (VerifyGameFile(path, false) == 0);
 
     lua_pushboolean(L, res);
     return 1;

arm9/source/system/itcm.h

@@ -162,6 +162,8 @@ typedef struct _Arm9Itcm {
 
 // Sanity checking.
 STATIC_ASSERT(offsetof(Arm9Itcm, otp) == 0x3800);
+STATIC_ASSERT(offsetof(Arm9Itcm, rsaModulusCartNCSD) == 0x4900);
+STATIC_ASSERT(offsetof(Arm9Itcm, rsaModulusAccessDesc) == 0x4A00);
 STATIC_ASSERT(offsetof(Arm9Itcm, twlNANDKeyY) == 0x53C8);
 STATIC_ASSERT(offsetof(Arm9Itcm, twlBlowfishCartKey) == 0x53E0);
 STATIC_ASSERT(offsetof(Arm9Itcm, ntrBlowfishCartKey) == 0x6428);

arm9/source/utils/gameutil.c

@@ -519,7 +519,7 @@ u32 VerifyTmdContent(const char* path, u64 offset, TmdContentChunk* chunk, const
     return memcmp(hash, expected, 32);
 }
 
-u32 VerifyNcchFile(const char* path, u32 offset, u32 size) {
+u32 VerifyNcchFile(const char* path, u32 offset, u32 size, bool sig_check) {
     static bool cryptofix_always = false;
     bool cryptofix = false;
     NcchHeader ncch;
@@ -583,6 +583,13 @@ u32 VerifyNcchFile(const char* path, u32 offset, u32 size) {
         return 1;
     }
 
+    // signature verification
+    if (sig_check && ValidateNcchSignature(&ncch, ncch.size_exthdr ? &exthdr : NULL) != 0) {
+        if (!offset) ShowPrompt(false, "%s\n%s", pathstr, STR_ERROR_SIGNATURE_CHECK_FAILED);
+        fvx_close(&file);
+        return 1;
+    }
+
     // check / setup crypto
     if (SetupNcchCrypto(&ncch, NCCH_NOCRYPTO) != 0) {
         if (!offset) ShowPrompt(false, "%s\n%s", pathstr, STR_ERROR_CRYPTO_NOT_SET_UP);
@@ -723,7 +730,7 @@ u32 VerifyNcchFile(const char* path, u32 offset, u32 size) {
     return ver_exthdr|ver_exefs|ver_romfs;
 }
 
-u32 VerifyNcsdFile(const char* path) {
+u32 VerifyNcsdFile(const char* path, bool sig_check) {
     NcsdHeader ncsd;
 
     // path string
@@ -736,13 +743,19 @@ u32 VerifyNcsdFile(const char* path) {
         return 1;
     }
 
+    // signature verification
+    if (sig_check && ValidateNcsdSignature(&ncsd) != 0) {
+        ShowPrompt(false, "%s\n%s", pathstr, STR_ERROR_SIGNATURE_CHECK_FAILED);
+        return 1;
+    }
+
     // validate NCSD contents
     for (u32 i = 0; i < 8; i++) {
         NcchPartition* partition = ncsd.partitions + i;
         u32 offset = partition->offset * NCSD_MEDIA_UNIT;
         u32 size = partition->size * NCSD_MEDIA_UNIT;
         if (!size) continue;
-        if (VerifyNcchFile(path, offset, size) != 0) {
+        if (VerifyNcchFile(path, offset, size, sig_check) != 0) {
             ShowPrompt(false, STR_PATH_CONTENT_N_SIZE_AT_OFFSET_VERIFICATION_FAILED,
                 pathstr, i, size, offset);
             return 1;
@@ -1032,14 +1045,14 @@ u32 VerifyTicketFile(const char* path) {
     return res;
 }
 
-u32 VerifyGameFile(const char* path) {
+u32 VerifyGameFile(const char* path, bool sig_check) {
     u64 filetype = IdentifyFileType(path);
     if (filetype & GAME_CIA)
         return VerifyCiaFile(path);
     else if (filetype & GAME_NCSD)
-        return VerifyNcsdFile(path);
+        return VerifyNcsdFile(path, sig_check);
     else if (filetype & GAME_NCCH)
-        return VerifyNcchFile(path, 0, 0);
+        return VerifyNcchFile(path, 0, 0, sig_check);
     else if (filetype & (GAME_TMD|GAME_CDNTMD|GAME_TWLTMD))
         return VerifyTmdFile(path, filetype & (GAME_CDNTMD|GAME_TWLTMD));
     else if (filetype & GAME_TIE)
@@ -3617,7 +3630,7 @@ u32 ShowGameCheckerInfo(const char* path) {
             (state_tmd == 0) ? STR_STATE_INVALID : (state_tmd == 2) ? STR_STATE_LEGIT : STR_STATE_ILLEGIT,
             (state_verify < 0) ? STR_STATE_PENDING_PROCEED_WITH_VERIFICATION : (state_verify == 0) ? STR_STATE_PASSED : STR_STATE_FAILED) ||
             (state_verify >= 0)) break;
-        state_verify = VerifyGameFile(path);
+        state_verify = VerifyGameFile(path, false);
     }
 
     if (tmd) free(tmd);

arm9/source/utils/gameutil.h

@@ -2,7 +2,7 @@
 
 #include "common.h"
 
-u32 VerifyGameFile(const char* path);
+u32 VerifyGameFile(const char* path, bool sig_check);
 u32 CheckEncryptedGameFile(const char* path);
 u32 CryptGameFile(const char* path, bool inplace, bool encrypt);
 u32 BuildCiaFromGameFile(const char* path, bool force_legit);

arm9/source/utils/scripting.c

@@ -1346,7 +1346,7 @@ bool run_cmd(cmd_id id, u32 flags, char** argv, char* err_str) {
     else if (id == CMD_ID_VERIFY) {
         u64 filetype = IdentifyFileType(argv[0]);
         if (filetype & IMG_NAND) ret = (ValidateNandDump(argv[0]) == 0);
-        else ret = (VerifyGameFile(argv[0]) == 0);
+        else ret = (VerifyGameFile(argv[0], false) == 0);
         if (err_str) snprintf(err_str, _ERR_STR_LEN, "%s", STR_VERIFICATION_FAILED);
     }
     else if (id == CMD_ID_DECRYPT) {

resources/languages/source.json

@@ -812,5 +812,9 @@
 	"SYSINFO_SYSTEM_ID0": "System ID0: %s\r\n",
 	"SYSINFO_SYSTEM_ID1": "System ID1: %s\r\n",
 	"SORTING_TICKETS_PLEASE_WAIT": "Sorting tickets, please wait ...",
-	"LUA_NOT_INCLUDED": "This build of GodMode9 was\ncompiled without Lua support."
+	"LUA_NOT_INCLUDED": "This build of GodMode9 was\ncompiled without Lua support.",
+	"ERROR_SIGNATURE_CHECK_FAILED": "Error: Signature check failed",
+	"USE_SIGNATURE_VERIFICATION": "Use signature verification?",
+	"IGNORE_SIGNATURES": "Ignore signatures",
+	"VERIFY_SIGNATURES": "Verify signatures"
 }