NPDM ACID public key replacement + NCA ACID signature recalculation.

source/nca.c

@@ -143,6 +143,9 @@ bool ncaInitializeContext(NcaContext *out, u8 storage_id, u8 hfs_partition_type,
         return false;
     }
     
+    /* Calculate decrypted header hash. */
+    sha256CalculateHash(out->header_hash, &(out->header), sizeof(NcaHeader));
+    
     if (out->rights_id_available)
     {
         /* Retrieve ticket. */
@@ -363,7 +366,6 @@ void ncaRemoveTitlekeyCrypto(NcaContext *ctx)
     
     /* Update context flags. */
     ctx->rights_id_available = false;
-    ctx->dirty_header = true;
 }
 
 bool ncaEncryptHeader(NcaContext *ctx)
@@ -375,7 +377,7 @@ bool ncaEncryptHeader(NcaContext *ctx)
     }
     
     /* Safety check: don't encrypt the header if we don't need to. */
-    if (!ctx->dirty_header) return true;
+    if (!ncaIsHeaderDirty(ctx)) return true;
     
     size_t crypt_res = 0;
     const u8 *header_key = keysGetNcaHeaderKey();
@@ -1068,9 +1070,6 @@ static bool ncaGenerateHashDataPatch(NcaFsSectionContext *ctx, const void *data,
     /* Recalculate FS header hash. */
     sha256CalculateHash(nca_ctx->header.fs_header_hash[ctx->section_num].hash, &(ctx->header), sizeof(NcaFsHeader));
     
-    /* Enable the 'dirty_header' flag. */
-    nca_ctx->dirty_header = true;
-    
     /* Copy content ID. */
     memcpy(!is_integrity_patch ? &(hierarchical_sha256_patch->content_id) : &(hierarchical_integrity_patch->content_id), &(nca_ctx->content_id), sizeof(NcmContentId));
     

source/nca.h

@@ -48,6 +48,8 @@
 
 #define NCA_AES_XTS_SECTOR_SIZE                     0x200
 
+#define NCA_ACID_SIGNATURE_AREA_SIZE                0x100                       /* Signature is calculated starting at the NCA header magic word. */
+
 typedef enum {
     NcaDistributionType_Download = 0,
     NcaDistributionType_GameCard = 1
@@ -312,8 +314,8 @@ typedef struct {
     bool rights_id_available;
     bool titlekey_retrieved;
     u8 titlekey[AES_128_KEY_SIZE];                          ///< Decrypted titlekey from the ticket.
-    bool dirty_header;
     NcaHeader header;                                       ///< NCA header.
+    u8 header_hash[SHA256_HASH_SIZE];                       ///< NCA header hash. Used to determine if it's necessary to replace the NCA header while dumping this NCA.
     NcaFsSectionContext fs_contexts[NCA_FS_HEADER_COUNT];
     NcaDecryptedKeyArea decrypted_key_area;
 } NcaContext;
@@ -368,7 +370,7 @@ void *ncaGenerateEncryptedFsSectionBlock(NcaFsSectionContext *ctx, const void *d
 
 /// Generates HierarchicalSha256 FS section patch data, which can be used to seamlessly replace NCA data.
 /// Input offset must be relative to the start of the last HierarchicalSha256 hash region (actual underlying FS).
-/// Bear in mind that this function recalculates both the NcaHashData block master hash and the NCA FS header hash from the NCA header, and enables the 'dirty_header' flag from the NCA context.
+/// Bear in mind that this function recalculates both the NcaHashData block master hash and the NCA FS header hash from the NCA header.
 /// As such, this function is not designed to generate more than one patch per HierarchicalSha256 FS section.
 bool ncaGenerateHierarchicalSha256Patch(NcaFsSectionContext *ctx, const void *data, u64 data_size, u64 data_offset, NcaHierarchicalSha256Patch *out);
 
@@ -378,7 +380,7 @@ void ncaWriteHierarchicalSha256PatchToMemoryBuffer(NcaContext *ctx, NcaHierarchi
 
 /// Generates HierarchicalIntegrity FS section patch data, which can be used to seamlessly replace NCA data.
 /// Input offset must be relative to the start of the last HierarchicalIntegrity hash level (actual underlying FS).
-/// Bear in mind that this function recalculates both the NcaHashData block master hash and the NCA FS header hash from the NCA header, and enables the 'dirty_header' flag from the NCA context.
+/// Bear in mind that this function recalculates both the NcaHashData block master hash and the NCA FS header hash from the NCA header.
 /// As such, this function is not designed to generate more than one patch per HierarchicalIntegrity FS section.
 bool ncaGenerateHierarchicalIntegrityPatch(NcaFsSectionContext *ctx, const void *data, u64 data_size, u64 data_offset, NcaHierarchicalIntegrityPatch *out);
 
@@ -425,7 +427,14 @@ NX_INLINE void ncaSetDownloadDistributionType(NcaContext *ctx)
 {
     if (!ctx || ctx->header.distribution_type == NcaDistributionType_Download) return;
     ctx->header.distribution_type = NcaDistributionType_Download;
-    ctx->dirty_header = true;
+}
+
+NX_INLINE bool ncaIsHeaderDirty(NcaContext *ctx)
+{
+    if (!ctx) return false;
+    u8 tmp_hash[SHA256_HASH_SIZE] = {0};
+    sha256CalculateHash(tmp_hash, &(ctx->header), sizeof(NcaHeader));
+    return (memcmp(tmp_hash, ctx->header_hash, SHA256_HASH_SIZE) != 0);
 }
 
 NX_INLINE bool ncaValidateHierarchicalSha256Offsets(NcaHierarchicalSha256Data *hierarchical_sha256_data, u64 section_size)

source/npdm.c

@@ -20,6 +20,7 @@
 
 #include "utils.h"
 #include "npdm.h"
+#include "rsa.h"
 
 bool npdmInitializeContext(NpdmContext *out, PartitionFileSystemContext *pfs_ctx)
 {
@@ -259,3 +260,26 @@ end:
     
     return success;
 }
+
+bool npdmChangeAcidPublicKeyAndNcaSignature(NpdmContext *npdm_ctx)
+{
+    NcaContext *nca_ctx = NULL;
+    
+    if (!npdmIsValidContext(npdm_ctx) || !(nca_ctx = (NcaContext*)npdm_ctx->pfs_ctx->nca_fs_ctx->nca_ctx) || nca_ctx->content_type != NcmContentType_Program)
+    {
+        LOGFILE("Invalid parameters!");
+        return false;
+    }
+    
+    /* Update NPDM ACID public key. */
+    memcpy(npdm_ctx->acid_header->public_key, rsa2048GetCustomPublicKey(), RSA2048_PUBKEY_SIZE);
+    
+    /* Update NCA ACID signature. */
+    if (!rsa2048GenerateSha256BasedPssSignature(nca_ctx->header.acid_signature, &(nca_ctx->header.magic), NCA_ACID_SIGNATURE_AREA_SIZE))
+    {
+        LOGFILE("Failed to generate RSA-2048-PSS NCA ACID signature!");
+        return false;
+    }
+    
+    return true;
+}

source/npdm.h

@@ -555,6 +555,9 @@ typedef struct {
 /// Initializes a NpdmContext using a previously initialized PartitionFileSystemContext (which must belong to the ExeFS from a Program NCA).
 bool npdmInitializeContext(NpdmContext *out, PartitionFileSystemContext *pfs_ctx);
 
+/// Changes the ACID public key from the NPDM in the input NpdmContext and updates the ACID signature from the NCA header in the underlying NCA context.
+bool npdmChangeAcidPublicKeyAndNcaSignature(NpdmContext *npdm_ctx);
+
 /// Helper inline functions.
 
 NX_INLINE void npdmFreeContext(NpdmContext *npdm_ctx)

source/nso.h

@@ -107,4 +107,36 @@ typedef struct {
     char name[];
 } NsoModuleInfo;
 
+
+
+
+/*
+
+
+typedef struct {
+    PartitionFileSystemContext *pfs_ctx;                        ///< PartitionFileSystemContext for the Program NCA FS section #0, which is where this NSO is stored.
+    PartitionFileSystemEntry *pfs_entry;                        ///< PartitionFileSystemEntry for this NSO in the Program NCA FS section #0. Used to read NSO data.
+    NsoHeader nso_header;                                       ///< Copy of the NSO header.
+    
+    
+    
+    
+    
+    
+} NsoContext;
+
+
+
+
+
+*/
+
+
+
+
+
+
+
+
+
 #endif /* __NSO_H__ */

source/rsa.h

@@ -26,6 +26,7 @@
 #define __RSA_H__
 
 #define RSA2048_SIG_SIZE    0x100
+#define RSA2048_PUBKEY_SIZE RSA2048_SIG_SIZE
 
 /// Generates a RSA-2048-PSS with SHA-256 signature using a custom RSA-2048 private key.
 /// Suitable to replace the ACID signature in a Program NCA header.

todo.txt

@@ -1,10 +1,8 @@
 todo:
     
     nca: functions for fs section lookup? (could just let the user choose...)
+    nca: add encrypted headers to nca context, avoid re-encrypting plaintext headers in place
     nca: function to write re-encrypted nca headers / nca fs headers (don't forget nca0 please)
-    nca: function to patch the private npdm acid signature from a program nca + patch the acid signature from the nca header
-    nca: add encrypted header to nca context, avoid re-encrypting the plaintext header in place
-    nca: use hash instead of dirty_header flag?
     
     tik: option to wipe elicense property mask
     tik: automatically dump tickets to the SD card?