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[nx] Add NcaUtils

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jakcron 2018-04-15 10:40:22 +08:00
parent 2573ad4b47
commit ee04bcdc8d
2 changed files with 62 additions and 0 deletions
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13
lib/libnx/include/nx/NcaUtils.h Normal file
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#pragma once
#include <nx/nca.h>
namespace nx
{
class NcaUtils
{
public:
static inline size_t sectorToOffset(size_t sector_index) { return sector_index * nx::nca::kSectorSize; }
static void decryptNcaHeader(const byte_t* src, byte_t* dst, const crypto::aes::sAesXts128Key& key);
static byte_t getMasterKeyRevisionFromKeyGeneration(byte_t key_generation);
};
}

49
lib/libnx/source/NcaUtils.cpp Normal file
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#include <nx/NcaUtils.h>
void nx::NcaUtils::decryptNcaHeader(const byte_t* src, byte_t* dst, const crypto::aes::sAesXts128Key& key)
{
byte_t tweak[crypto::aes::kAesBlockSize];
// decrypt main header
byte_t raw_hdr[nx::nca::kSectorSize];
crypto::aes::AesXtsMakeTweak(tweak, 1);
crypto::aes::AesXtsDecryptSector(src + sectorToOffset(1), nx::nca::kSectorSize, key.key[0], key.key[1], tweak, raw_hdr);
bool useNca2SectorIndex = memcmp(((nx::sNcaHeader*)(raw_hdr))->signature, nx::nca::kNca2Sig.c_str(), 4) == 0;
// decrypt whole header
for (size_t i = 0; i < nx::nca::kHeaderSectorNum; i++)
{
crypto::aes::AesXtsMakeTweak(tweak, (i > 1 && useNca2SectorIndex)? 0 : i);
crypto::aes::AesXtsDecryptSector(src + sectorToOffset(i), nx::nca::kSectorSize, key.key[0], key.key[1], tweak, dst + sectorToOffset(i));
}
}
byte_t nx::NcaUtils::getMasterKeyRevisionFromKeyGeneration(byte_t key_generation)
{
byte_t masterkey_rev;
switch (key_generation)
{
case(0):
case(1):
masterkey_rev = 0;
break;
case(2):
masterkey_rev = 1;
break;
case(3):
masterkey_rev = 2;
break;
case(4):
masterkey_rev = 3;
break;
case(5):
masterkey_rev = 4;
break;
default:
masterkey_rev = key_generation - 1;
}
return masterkey_rev;
}