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Partition keys don't need to be cached

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This commit is contained in:
Matt Nadareski
2026-03-22 01:06:36 -04:00
parent 28fe0a9f80
commit 76511a2f35
1 changed files with 62 additions and 47 deletions
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109
NDecrypt.Core/ThreeDSProcessor.cs
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@@ -206,11 +206,6 @@ namespace NDecrypt.Core
/// </summary>
private readonly bool _development;
/// <summary>
/// Set of all partition keys
/// </summary>
private readonly PartitionKeys[] _keysMap = new PartitionKeys[8];
#region Internal Test Values
/// <summary>
@@ -507,12 +502,17 @@ namespace NDecrypt.Core
private void DecryptPartition(N3DS cart, int index, Stream reader, Stream writer)
{
// Determine the keys needed for this partition
SetDecryptionKeys(cart, index);
PartitionKeys? keys = GetDecryptionKeys(cart, index);
if (keys == null)
{
Console.WriteLine($"Partition {index} could not generate keys. Skipping...");
return;
}
// Decrypt the parts of the partition
DecryptExtendedHeader(cart, index, reader, writer);
DecryptExeFS(cart, index, reader, writer);
DecryptRomFS(cart, index, reader, writer);
DecryptExtendedHeader(cart, index, keys, reader, writer);
DecryptExeFS(cart, index, keys, reader, writer);
DecryptRomFS(cart, index, keys, reader, writer);
// Update the flags
UpdateDecryptCryptoAndMasks(cart, index, writer);
@@ -523,12 +523,12 @@ namespace NDecrypt.Core
/// </summary>
/// <param name="cart">Cart representing the 3DS file</param>
/// <param name="index">Index of the partition</param>
private void SetDecryptionKeys(N3DS cart, int index)
private PartitionKeys? GetDecryptionKeys(N3DS cart, int index)
{
// Get the partition
var partition = cart.Partitions?[index];
if (partition?.Flags is null)
return;
return null;
// Get partition-specific values
byte[]? signature = partition.RSA2048Signature;
@@ -538,7 +538,7 @@ namespace NDecrypt.Core
// Get the partition keys
byte[] keyX = GetKeyXForCryptoMethod(method);
byte[] keyX0x2C = _development ? DevKeyX0x2C : KeyX0x2C;
_keysMap[index] = new PartitionKeys(signature, masks, AESHardwareConstant, keyX, keyX0x2C);
return new PartitionKeys(signature, masks, AESHardwareConstant, keyX, keyX0x2C);
}
/// <summary>
@@ -546,9 +546,10 @@ namespace NDecrypt.Core
/// </summary>
/// <param name="cart">Cart representing the 3DS file</param>
/// <param name="index">Index of the partition</param>
/// <param name="keys">Keys for the partition</param>
/// <param name="reader">Stream representing the input</param>
/// <param name="writer">Stream representing the output</param>
private bool DecryptExtendedHeader(N3DS cart, int index, Stream reader, Stream writer)
private bool DecryptExtendedHeader(N3DS cart, int index, PartitionKeys keys, Stream reader, Stream writer)
{
// Get required offsets
uint partitionOffset = cart.GetPartitionOffset(index);
@@ -572,7 +573,7 @@ namespace NDecrypt.Core
Console.WriteLine($"Partition {index}: Decrypting - ExHeader");
// Create the Plain AES cipher for this partition
var cipher = AESCTR.CreateDecryptionCipher(_keysMap[index].NormalKey2C, cart.PlainIV(index));
var cipher = AESCTR.CreateDecryptionCipher(keys.NormalKey2C, cart.PlainIV(index));
// Process the extended header
AESCTR.PerformOperation(CXTExtendedDataHeaderLength, cipher, reader, writer, null);
@@ -590,9 +591,10 @@ namespace NDecrypt.Core
/// </summary>
/// <param name="cart">Cart representing the 3DS file</param>
/// <param name="index">Index of the partition</param>
/// <param name="keys">Keys for the partition</param>
/// <param name="reader">Stream representing the input</param>
/// <param name="writer">Stream representing the output</param>
private bool DecryptExeFS(N3DS cart, int index, Stream reader, Stream writer)
private bool DecryptExeFS(N3DS cart, int index, PartitionKeys keys, Stream reader, Stream writer)
{
// Validate the ExeFS
uint exeFsHeaderOffset = cart.GetExeFSOffset(index);
@@ -610,11 +612,11 @@ namespace NDecrypt.Core
}
// Decrypt the filename table
DecryptExeFSFilenameTable(cart, index, reader, writer);
DecryptExeFSFilenameTable(cart, index, keys, reader, writer);
// For all but the original crypto method, process each of the files in the table
if (cart.GetCryptoMethod(index) != CryptoMethod.Original)
DecryptExeFSFileEntries(cart, index, reader, writer);
DecryptExeFSFileEntries(cart, index, keys, reader, writer);
// Get the ExeFS files offset
uint exeFsFilesOffset = exeFsHeaderOffset + cart.MediaUnitSize;
@@ -626,7 +628,7 @@ namespace NDecrypt.Core
// Create the ExeFS AES cipher for this partition
uint ctroffsetE = cart.MediaUnitSize / 0x10;
byte[] exefsIVWithOffset = cart.ExeFSIV(index).Add(ctroffsetE);
var cipher = AESCTR.CreateDecryptionCipher(_keysMap[index].NormalKey2C, exefsIVWithOffset);
var cipher = AESCTR.CreateDecryptionCipher(keys.NormalKey2C, exefsIVWithOffset);
// Setup and perform the decryption
exeFsSize -= cart.MediaUnitSize;
@@ -644,9 +646,10 @@ namespace NDecrypt.Core
/// </summary>
/// <param name="cart">Cart representing the 3DS file</param>
/// <param name="index">Index of the partition</param>
/// <param name="keys">Keys for the partition</param>
/// <param name="reader">Stream representing the input</param>
/// <param name="writer">Stream representing the output</param>
private void DecryptExeFSFilenameTable(N3DS cart, int index, Stream reader, Stream writer)
private void DecryptExeFSFilenameTable(N3DS cart, int index, PartitionKeys keys, Stream reader, Stream writer)
{
// Get ExeFS offset
uint exeFsOffset = cart.GetExeFSOffset(index);
@@ -663,7 +666,7 @@ namespace NDecrypt.Core
Console.WriteLine($"Partition {index} ExeFS: Decrypting - ExeFS Filename Table");
// Create the ExeFS AES cipher for this partition
var cipher = AESCTR.CreateDecryptionCipher(_keysMap[index].NormalKey2C, cart.ExeFSIV(index));
var cipher = AESCTR.CreateDecryptionCipher(keys.NormalKey2C, cart.ExeFSIV(index));
// Process the filename table
byte[] readBytes = reader.ReadBytes((int)cart.MediaUnitSize);
@@ -682,9 +685,10 @@ namespace NDecrypt.Core
/// </summary>
/// <param name="cart">Cart representing the 3DS file</param>
/// <param name="index">Index of the partition</param>
/// <param name="keys">Keys for the partition</param>
/// <param name="reader">Stream representing the input</param>
/// <param name="writer">Stream representing the output</param>
private void DecryptExeFSFileEntries(N3DS cart, int index, Stream reader, Stream writer)
private void DecryptExeFSFileEntries(N3DS cart, int index, PartitionKeys keys, Stream reader, Stream writer)
{
if (cart.ExeFSHeaders is null || index < 0 || index > cart.ExeFSHeaders.Length)
{
@@ -723,8 +727,8 @@ namespace NDecrypt.Core
// Create the ExeFS AES ciphers for this partition
uint ctroffset = (fileHeader.FileOffset + cart.MediaUnitSize) / 0x10;
byte[] exefsIVWithOffsetForHeader = cart.ExeFSIV(index).Add(ctroffset);
var firstCipher = AESCTR.CreateDecryptionCipher(_keysMap[index].NormalKey, exefsIVWithOffsetForHeader);
var secondCipher = AESCTR.CreateEncryptionCipher(_keysMap[index].NormalKey2C, exefsIVWithOffsetForHeader);
var firstCipher = AESCTR.CreateDecryptionCipher(keys.NormalKey, exefsIVWithOffsetForHeader);
var secondCipher = AESCTR.CreateEncryptionCipher(keys.NormalKey2C, exefsIVWithOffsetForHeader);
// Seek to the file entry
reader.Seek(exeFsFilesOffset + fileHeader.FileOffset, SeekOrigin.Begin);
@@ -744,10 +748,11 @@ namespace NDecrypt.Core
/// Decrypt the RomFS, if it exists
/// </summary>
/// <param name="cart">Cart representing the 3DS file</param>
/// <param name="keys">Keys for the partition</param>
/// <param name="index">Index of the partition</param>
/// <param name="reader">Stream representing the input</param>
/// <param name="writer">Stream representing the output</param>
private bool DecryptRomFS(N3DS cart, int index, Stream reader, Stream writer)
private bool DecryptRomFS(N3DS cart, int index, PartitionKeys keys, Stream reader, Stream writer)
{
// Validate the RomFS
uint romFsOffset = cart.GetRomFSOffset(index);
@@ -769,7 +774,7 @@ namespace NDecrypt.Core
writer.Seek(romFsOffset, SeekOrigin.Begin);
// Create the RomFS AES cipher for this partition
var cipher = AESCTR.CreateDecryptionCipher(_keysMap[index].NormalKey, cart.RomFSIV(index));
var cipher = AESCTR.CreateDecryptionCipher(keys.NormalKey, cart.RomFSIV(index));
// Setup and perform the decryption
AESCTR.PerformOperation(romFsSize,
@@ -922,12 +927,17 @@ namespace NDecrypt.Core
private void EncryptPartition(N3DS cart, int index, Stream reader, Stream writer)
{
// Determine the keys needed for this partition
SetEncryptionKeys(cart, index);
PartitionKeys? keys = GetEncryptionKeys(cart, index);
if (keys == null)
{
Console.WriteLine($"Partition {index} could not generate keys. Skipping...");
return;
}
// Encrypt the parts of the partition
EncryptExtendedHeader(cart, index, reader, writer);
EncryptExeFS(cart, index, reader, writer);
EncryptRomFS(cart, index, reader, writer);
EncryptExtendedHeader(cart, index, keys, reader, writer);
EncryptExeFS(cart, index, keys, reader, writer);
EncryptRomFS(cart, index, keys, reader, writer);
// Update the flags
UpdateEncryptCryptoAndMasks(cart, index, writer);
@@ -938,17 +948,17 @@ namespace NDecrypt.Core
/// </summary>
/// <param name="cart">Cart representing the 3DS file</param>
/// <param name="index">Index of the partition</param>
private void SetEncryptionKeys(N3DS cart, int index)
private PartitionKeys? GetEncryptionKeys(N3DS cart, int index)
{
// Get the partition
var partition = cart.Partitions?[index];
if (partition is null)
return;
return null;
// Get the backup header
var backupHeader = cart.BackupHeader;
if (backupHeader?.Flags is null)
return;
return null;
// Get partition-specific values
byte[]? signature = partition.RSA2048Signature;
@@ -958,7 +968,7 @@ namespace NDecrypt.Core
// Get the partition keys
byte[] keyX = GetKeyXForCryptoMethod(method);
byte[] keyX0x2C = _development ? DevKeyX0x2C : KeyX0x2C;
_keysMap[index] = new PartitionKeys(signature, masks, AESHardwareConstant, keyX, keyX0x2C);
return new PartitionKeys(signature, masks, AESHardwareConstant, keyX, keyX0x2C);
}
/// <summary>
@@ -966,9 +976,10 @@ namespace NDecrypt.Core
/// </summary>
/// <param name="cart">Cart representing the 3DS file</param>
/// <param name="index">Index of the partition</param>
/// <param name="keys">Keys for the partition</param>
/// <param name="reader">Stream representing the input</param>
/// <param name="writer">Stream representing the output</param>
private bool EncryptExtendedHeader(N3DS cart, int index, Stream reader, Stream writer)
private bool EncryptExtendedHeader(N3DS cart, int index, PartitionKeys keys, Stream reader, Stream writer)
{
// Get required offsets
uint partitionOffset = cart.GetPartitionOffset(index);
@@ -992,7 +1003,7 @@ namespace NDecrypt.Core
Console.WriteLine($"Partition {index}: Encrypting - ExHeader");
// Create the Plain AES cipher for this partition
var cipher = AESCTR.CreateEncryptionCipher(_keysMap[index].NormalKey2C, cart.PlainIV(index));
var cipher = AESCTR.CreateEncryptionCipher(keys.NormalKey2C, cart.PlainIV(index));
// Process the extended header
AESCTR.PerformOperation(CXTExtendedDataHeaderLength, cipher, reader, writer, null);
@@ -1010,9 +1021,10 @@ namespace NDecrypt.Core
/// </summary>
/// <param name="cart">Cart representing the 3DS file</param>
/// <param name="index">Index of the partition</param>
/// <param name="keys">Keys for the partition</param>
/// <param name="reader">Stream representing the input</param>
/// <param name="writer">Stream representing the output</param>
private bool EncryptExeFS(N3DS cart, int index, Stream reader, Stream writer)
private bool EncryptExeFS(N3DS cart, int index, PartitionKeys keys, Stream reader, Stream writer)
{
if (cart.ExeFSHeaders is null || index < 0 || index > cart.ExeFSHeaders.Length)
{
@@ -1031,10 +1043,10 @@ namespace NDecrypt.Core
// For all but the original crypto method, process each of the files in the table
var backupHeader = cart.BackupHeader;
if (backupHeader!.Flags!.CryptoMethod != CryptoMethod.Original)
EncryptExeFSFileEntries(cart, index, reader, writer);
EncryptExeFSFileEntries(cart, index, keys, reader, writer);
// Encrypt the filename table
EncryptExeFSFilenameTable(cart, index, reader, writer);
EncryptExeFSFilenameTable(cart, index, keys, reader, writer);
// Get the ExeFS files offset
uint exeFsHeaderOffset = cart.GetExeFSOffset(index);
@@ -1047,7 +1059,7 @@ namespace NDecrypt.Core
// Create the ExeFS AES cipher for this partition
uint ctroffsetE = cart.MediaUnitSize / 0x10;
byte[] exefsIVWithOffset = cart.ExeFSIV(index).Add(ctroffsetE);
var cipher = AESCTR.CreateEncryptionCipher(_keysMap[index].NormalKey2C, exefsIVWithOffset);
var cipher = AESCTR.CreateEncryptionCipher(keys.NormalKey2C, exefsIVWithOffset);
// Setup and perform the encryption
uint exeFsSize = cart.GetExeFSSize(index) - cart.MediaUnitSize;
@@ -1065,9 +1077,10 @@ namespace NDecrypt.Core
/// </summary>
/// <param name="cart">Cart representing the 3DS file</param>
/// <param name="index">Index of the partition</param>
/// <param name="keys">Keys for the partition</param>
/// <param name="reader">Stream representing the input</param>
/// <param name="writer">Stream representing the output</param>
private void EncryptExeFSFilenameTable(N3DS cart, int index, Stream reader, Stream writer)
private void EncryptExeFSFilenameTable(N3DS cart, int index, PartitionKeys keys, Stream reader, Stream writer)
{
// Get ExeFS offset
uint exeFsOffset = cart.GetExeFSOffset(index);
@@ -1084,7 +1097,7 @@ namespace NDecrypt.Core
Console.WriteLine($"Partition {index} ExeFS: Encrypting - ExeFS Filename Table");
// Create the ExeFS AES cipher for this partition
var cipher = AESCTR.CreateEncryptionCipher(_keysMap[index].NormalKey2C, cart.ExeFSIV(index));
var cipher = AESCTR.CreateEncryptionCipher(keys.NormalKey2C, cart.ExeFSIV(index));
// Process the filename table
byte[] readBytes = reader.ReadBytes((int)cart.MediaUnitSize);
@@ -1103,9 +1116,10 @@ namespace NDecrypt.Core
/// </summary>
/// <param name="cart">Cart representing the 3DS file</param>
/// <param name="index">Index of the partition</param>
/// <param name="keys">Keys for the partition</param>
/// <param name="reader">Stream representing the input</param>
/// <param name="writer">Stream representing the output</param>
private void EncryptExeFSFileEntries(N3DS cart, int index, Stream reader, Stream writer)
private void EncryptExeFSFileEntries(N3DS cart, int index, PartitionKeys keys, Stream reader, Stream writer)
{
// Get ExeFS offset
uint exeFsHeaderOffset = cart.GetExeFSOffset(index);
@@ -1141,8 +1155,8 @@ namespace NDecrypt.Core
// Create the ExeFS AES ciphers for this partition
uint ctroffset = (fileHeader.FileOffset + cart.MediaUnitSize) / 0x10;
byte[] exefsIVWithOffsetForHeader = cart.ExeFSIV(index).Add(ctroffset);
var firstCipher = AESCTR.CreateEncryptionCipher(_keysMap[index].NormalKey, exefsIVWithOffsetForHeader);
var secondCipher = AESCTR.CreateDecryptionCipher(_keysMap[index].NormalKey2C, exefsIVWithOffsetForHeader);
var firstCipher = AESCTR.CreateEncryptionCipher(keys.NormalKey, exefsIVWithOffsetForHeader);
var secondCipher = AESCTR.CreateDecryptionCipher(keys.NormalKey2C, exefsIVWithOffsetForHeader);
// Seek to the file entry
reader.Seek(exeFsFilesOffset + fileHeader.FileOffset, SeekOrigin.Begin);
@@ -1163,9 +1177,10 @@ namespace NDecrypt.Core
/// </summary>
/// <param name="cart">Cart representing the 3DS file</param>
/// <param name="index">Index of the partition</param>
/// <param name="keys">Keys for the partition</param>
/// <param name="reader">Stream representing the input</param>
/// <param name="writer">Stream representing the output</param>
private bool EncryptRomFS(N3DS cart, int index, Stream reader, Stream writer)
private bool EncryptRomFS(N3DS cart, int index, PartitionKeys keys, Stream reader, Stream writer)
{
// Validate the RomFS
uint romFsOffset = cart.GetRomFSOffset(index);
@@ -1190,13 +1205,13 @@ namespace NDecrypt.Core
if (index > 0)
{
var backupHeader = cart.BackupHeader;
_keysMap[index].SetRomFSValues(backupHeader.Flags.BitMasks,
keys.SetRomFSValues(backupHeader.Flags.BitMasks,
hardwareConstant: AESHardwareConstant,
keyX0x2C: _development ? DevKeyX0x2C : KeyX0x2C);
}
// Create the RomFS AES cipher for this partition
var cipher = AESCTR.CreateEncryptionCipher(_keysMap[index].NormalKey, cart.RomFSIV(index));
var cipher = AESCTR.CreateEncryptionCipher(keys.NormalKey, cart.RomFSIV(index));
// Setup and perform the decryption
AESCTR.PerformOperation(romFsSize,