public static RSAParameters DecryptRsaKey(byte[] encryptedKey, byte[] kek)
{
var counter = new byte[0x10];
Array.Copy(encryptedKey, counter, 0x10);
var body = new byte[0x230];
Array.Copy(encryptedKey, 0x10, body, 0, 0x230);
var dec = new byte[0x230];
using (var streamDec = new RandomAccessSectorStream(new Aes128CtrStream(new MemoryStream(body), kek, counter)))
{
streamDec.Read(dec, 0, dec.Length);
}
var d = new byte[0x100];
var n = new byte[0x100];
var e = new byte[4];
Array.Copy(dec, 0, d, 0, 0x100);
Array.Copy(dec, 0x100, n, 0, 0x100);
Array.Copy(dec, 0x200, e, 0, 4);
BigInteger dInt = GetBigInteger(d);
BigInteger nInt = GetBigInteger(n);
BigInteger eInt = GetBigInteger(e);
RSAParameters rsaParams = RecoverRsaParameters(nInt, eInt, dInt);
TestRsaKey(rsaParams);
return(rsaParams);
}
private void DecryptKeyblobs(IProgressReport logger = null)
{
var cmac = new byte[0x10];
var expectedCmac = new byte[0x10];
var counter = new byte[0x10];
for (int i = 0; i < 0x20; i++)
{
if (KeyblobKeys[i].IsEmpty() || KeyblobMacKeys[i].IsEmpty() || EncryptedKeyblobs[i].IsEmpty())
{
continue;
}
Array.Copy(EncryptedKeyblobs[i], expectedCmac, 0x10);
Crypto.CalculateAesCmac(KeyblobMacKeys[i], EncryptedKeyblobs[i], 0x10, cmac, 0, 0xa0);
if (!Util.ArraysEqual(cmac, expectedCmac))
{
logger?.LogMessage($"Warning: Keyblob MAC {i:x2} is invalid. Are SBK/TSEC key correct?");
}
Array.Copy(EncryptedKeyblobs[i], 0x10, counter, 0, 0x10);
using (var keyblobDec = new RandomAccessSectorStream(new Aes128CtrStream(
new MemoryStream(EncryptedKeyblobs[i], 0x20, Keyblobs[i].Length), KeyblobKeys[i], counter)))
{
keyblobDec.Read(Keyblobs[i], 0, Keyblobs[i].Length);
}
}
}
public BktrCryptoStream(Stream baseStream, byte[] key, long offset, long length, long counterOffset, byte[] ctrHi, BktrSuperblock bktr)
: base(baseStream, key, offset, length, counterOffset, ctrHi)
{
BktrHeader header = bktr.SubsectionHeader;
byte[] subsectionBytes;
using (var streamDec = new RandomAccessSectorStream(new Aes128CtrStream(baseStream, key, offset, length, counterOffset, ctrHi)))
{
streamDec.Position = header.Offset;
subsectionBytes = new byte[header.Size];
streamDec.Read(subsectionBytes, 0, subsectionBytes.Length);
}
using (var reader = new BinaryReader(new MemoryStream(subsectionBytes)))
{
SubsectionBlock = new SubsectionBlock(reader);
}
foreach (SubsectionBucket bucket in SubsectionBlock.Buckets)
{
SubsectionEntries.AddRange(bucket.Entries);
}
// Add a subsection for the BKTR headers to make things easier
var headerSubsection = new SubsectionEntry
{
Offset = bktr.RelocationHeader.Offset,
Counter = (uint)(ctrHi[4] << 24 | ctrHi[5] << 16 | ctrHi[6] << 8 | ctrHi[7]),
OffsetEnd = long.MaxValue
};
SubsectionEntries.Add(headerSubsection);
for (int i = 0; i < SubsectionEntries.Count - 1; i++)
{
SubsectionEntries[i].Next = SubsectionEntries[i + 1];
SubsectionEntries[i].OffsetEnd = SubsectionEntries[i + 1].Offset;
}
SubsectionOffsets = SubsectionEntries.Select(x => x.Offset).ToList();
CurrentEntry = GetSubsectionEntry(0);
UpdateCounterSubsection(CurrentEntry.Counter);
baseStream.Position = offset;
}