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core: nfp: Remove magic numbers

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This commit is contained in:
german77 2022-09-07 01:03:02 -05:00
parent 4834961736
commit 063b23cc58
3 changed files with 98 additions and 100 deletions
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151
src/core/hle/service/nfp/amiibo_crypto.cpp
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@ -70,10 +70,10 @@ bool IsAmiiboValid(const EncryptedNTAG215File& ntag_file) {
NTAG215File NfcDataToEncodedData(const EncryptedNTAG215File& nfc_data) {
NTAG215File encoded_data{};
memcpy(encoded_data.uuid2.data(), nfc_data.uuid.data() + 0x8, 2);
memcpy(encoded_data.uuid2.data(), nfc_data.uuid.data() + 0x8, sizeof(encoded_data.uuid2));
encoded_data.static_lock = nfc_data.static_lock;
encoded_data.compability_container = nfc_data.compability_container;
encoded_data.unfixed_hash = nfc_data.user_memory.unfixed_hash;
encoded_data.hmac_data = nfc_data.user_memory.hmac_data;
encoded_data.constant_value = nfc_data.user_memory.constant_value;
encoded_data.write_counter = nfc_data.user_memory.write_counter;
encoded_data.settings = nfc_data.user_memory.settings;
@ -84,8 +84,8 @@ NTAG215File NfcDataToEncodedData(const EncryptedNTAG215File& nfc_data) {
encoded_data.unknown = nfc_data.user_memory.unknown;
encoded_data.hash = nfc_data.user_memory.hash;
encoded_data.application_area = nfc_data.user_memory.application_area;
encoded_data.locked_hash = nfc_data.user_memory.locked_hash;
memcpy(encoded_data.uuid.data(), nfc_data.uuid.data(), 8);
encoded_data.hmac_tag = nfc_data.user_memory.hmac_tag;
memcpy(encoded_data.uuid.data(), nfc_data.uuid.data(), sizeof(encoded_data.uuid));
encoded_data.model_info = nfc_data.user_memory.model_info;
encoded_data.keygen_salt = nfc_data.user_memory.keygen_salt;
encoded_data.dynamic_lock = nfc_data.dynamic_lock;
@ -99,11 +99,11 @@ NTAG215File NfcDataToEncodedData(const EncryptedNTAG215File& nfc_data) {
EncryptedNTAG215File EncodedDataToNfcData(const NTAG215File& encoded_data) {
EncryptedNTAG215File nfc_data{};
memcpy(nfc_data.uuid.data() + 0x8, encoded_data.uuid2.data(), 2);
memcpy(nfc_data.uuid.data(), encoded_data.uuid.data(), 8);
memcpy(nfc_data.uuid.data() + 0x8, encoded_data.uuid2.data(), sizeof(encoded_data.uuid2));
memcpy(nfc_data.uuid.data(), encoded_data.uuid.data(), sizeof(encoded_data.uuid));
nfc_data.static_lock = encoded_data.static_lock;
nfc_data.compability_container = encoded_data.compability_container;
nfc_data.user_memory.unfixed_hash = encoded_data.unfixed_hash;
nfc_data.user_memory.hmac_data = encoded_data.hmac_data;
nfc_data.user_memory.constant_value = encoded_data.constant_value;
nfc_data.user_memory.write_counter = encoded_data.write_counter;
nfc_data.user_memory.settings = encoded_data.settings;
@ -114,7 +114,7 @@ EncryptedNTAG215File EncodedDataToNfcData(const NTAG215File& encoded_data) {
nfc_data.user_memory.unknown = encoded_data.unknown;
nfc_data.user_memory.hash = encoded_data.hash;
nfc_data.user_memory.application_area = encoded_data.application_area;
nfc_data.user_memory.locked_hash = encoded_data.locked_hash;
nfc_data.user_memory.hmac_tag = encoded_data.hmac_tag;
nfc_data.user_memory.model_info = encoded_data.model_info;
nfc_data.user_memory.keygen_salt = encoded_data.keygen_salt;
nfc_data.dynamic_lock = encoded_data.dynamic_lock;
@ -136,60 +136,53 @@ u32 GetTagPassword(const TagUuid& uuid) {
HashSeed GetSeed(const NTAG215File& data) {
HashSeed seed{
.data =
{
.magic = data.write_counter,
.padding = {},
.uuid1 = {},
.uuid2 = {},
.keygen_salt = data.keygen_salt,
},
};
// Copy the first 8 bytes of uuid
memcpy(seed.data.uuid1.data(), data.uuid.data(), sizeof(seed.data.uuid1));
memcpy(seed.data.uuid2.data(), data.uuid.data(), sizeof(seed.data.uuid2));
memcpy(seed.uuid1.data(), data.uuid.data(), sizeof(seed.uuid1));
memcpy(seed.uuid2.data(), data.uuid.data(), sizeof(seed.uuid2));
return seed;
}
void PreGenerateKey(const InternalKey& key, const HashSeed& seed, u8* output,
std::size_t& outputLen) {
std::size_t index = 0;
std::vector<u8> GenerateInternalKey(const InternalKey& key, const HashSeed& seed) {
const std::size_t seedPart1Len = sizeof(key.magic_bytes) - key.magic_length;
const std::size_t string_size = key.type_string.size();
std::vector<u8> output(string_size + seedPart1Len);
// Copy whole type string
memccpy(output + index, key.type_string.data(), '\0', key.type_string.size());
index += key.type_string.size();
memccpy(output.data(), key.type_string.data(), '\0', string_size);
// Append (16 - magic_length) from the input seed
std::size_t seedPart1Len = 16 - key.magic_length;
memcpy(output + index, &seed, seedPart1Len);
index += seedPart1Len;
memcpy(output.data() + string_size, &seed, seedPart1Len);
// Append all bytes from magicBytes
memcpy(output + index, &key.magic_bytes, key.magic_length);
index += key.magic_length;
output.insert(output.end(), key.magic_bytes.begin(),
key.magic_bytes.begin() + key.magic_length);
// Seed 16 bytes at +0x10
memcpy(output + index, &seed.raw[0x10], 16);
index += 16;
output.insert(output.end(), seed.uuid1.begin(), seed.uuid1.end());
output.insert(output.end(), seed.uuid2.begin(), seed.uuid2.end());
// 32 bytes at +0x20 from input seed xored with xor pad
for (std::size_t i = 0; i < 32; i++)
output[index + i] = seed.raw[i + 32] ^ key.xor_pad[i];
index += 32;
for (std::size_t i = 0; i < sizeof(seed.keygen_salt); i++) {
output.emplace_back(static_cast<u8>(seed.keygen_salt[i] ^ key.xor_pad[i]));
}
outputLen = index;
return output;
}
void CryptoInit(CryptoCtx& ctx, mbedtls_md_context_t& hmac_ctx, const HmacKey& hmac_key,
const u8* seed, std::size_t seed_size) {
const std::vector<u8>& seed) {
// Initialize context
ctx.used = false;
ctx.counter = 0;
ctx.buffer_size = sizeof(ctx.counter) + seed_size;
memcpy(ctx.buffer.data() + sizeof(u16), seed, seed_size);
ctx.buffer_size = sizeof(ctx.counter) + seed.size();
memcpy(ctx.buffer.data() + sizeof(u16), seed.data(), seed.size());
// Initialize HMAC context
mbedtls_md_init(&hmac_ctx);
@ -217,18 +210,15 @@ void CryptoStep(CryptoCtx& ctx, mbedtls_md_context_t& hmac_ctx, DrgbOutput& outp
}
DerivedKeys GenerateKey(const InternalKey& key, const NTAG215File& data) {
constexpr std::size_t OUTPUT_SIZE = 512;
const auto seed = GetSeed(data);
// Generate internal seed
u8 internal_key[OUTPUT_SIZE];
std::size_t internal_key_lenght = 0;
PreGenerateKey(key, seed, internal_key, internal_key_lenght);
const std::vector<u8> internal_key = GenerateInternalKey(key, seed);
// Initialize context
CryptoCtx ctx{};
mbedtls_md_context_t hmac_ctx;
CryptoInit(ctx, hmac_ctx, key.hmac_key, internal_key, internal_key_lenght);
CryptoInit(ctx, hmac_ctx, key.hmac_key, internal_key);
// Generate derived keys
DerivedKeys derived_keys{};
@ -246,27 +236,34 @@ DerivedKeys GenerateKey(const InternalKey& key, const NTAG215File& data) {
void Cipher(const DerivedKeys& keys, const NTAG215File& in_data, NTAG215File& out_data) {
mbedtls_aes_context aes;
std::size_t nc_off = 0;
std::array<u8, 0x10> nonce_counter{};
std::array<u8, 0x10> stream_block{};
std::array<u8, sizeof(keys.aes_iv)> nonce_counter{};
std::array<u8, sizeof(keys.aes_iv)> stream_block{};
mbedtls_aes_setkey_enc(&aes, keys.aes_key.data(), 128);
memcpy(nonce_counter.data(), keys.aes_iv.data(), sizeof(nonce_counter));
const auto aes_key_size = static_cast<u32>(keys.aes_key.size() * 8);
mbedtls_aes_setkey_enc(&aes, keys.aes_key.data(), aes_key_size);
memcpy(nonce_counter.data(), keys.aes_iv.data(), sizeof(keys.aes_iv));
std::array<u8, sizeof(NTAG215File)> in_data_byes{};
std::array<u8, sizeof(NTAG215File)> out_data_bytes{};
memcpy(in_data_byes.data(), &in_data, sizeof(NTAG215File));
memcpy(out_data_bytes.data(), &out_data, sizeof(NTAG215File));
constexpr std::size_t encrypted_data_size = HMAC_TAG_START - SETTINGS_START;
mbedtls_aes_crypt_ctr(&aes, encrypted_data_size, &nc_off, nonce_counter.data(),
stream_block.data(),
reinterpret_cast<const unsigned char*>(&in_data.settings),
reinterpret_cast<unsigned char*>(&out_data.settings));
mbedtls_aes_crypt_ctr(&aes, 0x188, &nc_off, nonce_counter.data(), stream_block.data(),
in_data_byes.data() + 0x2c, out_data_bytes.data() + 0x2c);
// Copy the rest of the data directly
out_data.uuid2 = in_data.uuid2;
out_data.static_lock = in_data.static_lock;
out_data.compability_container = in_data.compability_container;
memcpy(out_data_bytes.data(), in_data_byes.data(), 0x008);
// Data signature NOT copied
memcpy(out_data_bytes.data() + 0x028, in_data_byes.data() + 0x028, 0x004);
// Tag signature NOT copied
memcpy(out_data_bytes.data() + 0x1D4, in_data_byes.data() + 0x1D4, 0x048);
out_data.constant_value = in_data.constant_value;
out_data.write_counter = in_data.write_counter;
memcpy(&out_data, out_data_bytes.data(), sizeof(NTAG215File));
out_data.uuid = in_data.uuid;
out_data.model_info = in_data.model_info;
out_data.keygen_salt = in_data.keygen_salt;
out_data.dynamic_lock = in_data.dynamic_lock;
out_data.CFG0 = in_data.CFG0;
out_data.CFG1 = in_data.CFG1;
out_data.password = in_data.password;
}
bool LoadKeys(InternalKey& locked_secret, InternalKey& unfixed_info) {
@ -309,26 +306,26 @@ bool DecodeAmiibo(const EncryptedNTAG215File& encrypted_tag_data, NTAG215File& t
// Decrypt
Cipher(data_keys, encoded_data, tag_data);
std::array<u8, sizeof(NTAG215File)> out{};
memcpy(out.data(), &tag_data, sizeof(NTAG215File));
// Regenerate tag HMAC. Note: order matters, data HMAC depends on tag HMAC!
constexpr std::size_t input_length = DYNAMIC_LOCK_START - UUID_START;
mbedtls_md_hmac(mbedtls_md_info_from_type(MBEDTLS_MD_SHA256), tag_keys.hmac_key.data(),
sizeof(HmacKey), out.data() + 0x1D4, 0x34, out.data() + HMAC_POS_TAG);
sizeof(HmacKey), reinterpret_cast<const unsigned char*>(&tag_data.uuid),
input_length, reinterpret_cast<unsigned char*>(&tag_data.hmac_tag));
// Regenerate data HMAC
constexpr std::size_t input_length2 = DYNAMIC_LOCK_START - WRITE_COUNTER_START;
mbedtls_md_hmac(mbedtls_md_info_from_type(MBEDTLS_MD_SHA256), data_keys.hmac_key.data(),
sizeof(HmacKey), out.data() + 0x29, 0x1DF, out.data() + HMAC_POS_DATA);
sizeof(HmacKey),
reinterpret_cast<const unsigned char*>(&tag_data.write_counter), input_length2,
reinterpret_cast<unsigned char*>(&tag_data.hmac_data));
memcpy(&tag_data, out.data(), sizeof(NTAG215File));
if (memcmp(tag_data.unfixed_hash.data(), encrypted_tag_data.user_memory.unfixed_hash.data(),
32) != 0) {
if (tag_data.hmac_data != encrypted_tag_data.user_memory.hmac_data) {
LOG_ERROR(Service_NFP, "hmac_data doesn't match");
return false;
}
if (memcmp(tag_data.locked_hash.data(), encrypted_tag_data.user_memory.locked_hash.data(),
32) != 0) {
if (tag_data.hmac_tag != encrypted_tag_data.user_memory.hmac_tag) {
LOG_ERROR(Service_NFP, "hmac_tag doesn't match");
return false;
}
@ -347,13 +344,14 @@ bool EncodeAmiibo(const NTAG215File& tag_data, EncryptedNTAG215File& encrypted_t
const auto data_keys = GenerateKey(unfixed_info, tag_data);
const auto tag_keys = GenerateKey(locked_secret, tag_data);
std::array<u8, sizeof(NTAG215File)> plain{};
std::array<u8, sizeof(NTAG215File)> cipher{};
memcpy(plain.data(), &tag_data, sizeof(NTAG215File));
NTAG215File encoded_tag_data{};
// Generate tag HMAC
constexpr std::size_t input_length = DYNAMIC_LOCK_START - UUID_START;
constexpr std::size_t input_length2 = HMAC_TAG_START - WRITE_COUNTER_START;
mbedtls_md_hmac(mbedtls_md_info_from_type(MBEDTLS_MD_SHA256), tag_keys.hmac_key.data(),
sizeof(HmacKey), plain.data() + 0x1D4, 0x34, cipher.data() + HMAC_POS_TAG);
sizeof(HmacKey), reinterpret_cast<const unsigned char*>(&tag_data.uuid),
input_length, reinterpret_cast<unsigned char*>(&encoded_tag_data.hmac_tag));
// Init mbedtls HMAC context
mbedtls_md_context_t ctx;
@ -362,17 +360,18 @@ bool EncodeAmiibo(const NTAG215File& tag_data, EncryptedNTAG215File& encrypted_t
// Generate data HMAC
mbedtls_md_hmac_starts(&ctx, data_keys.hmac_key.data(), sizeof(HmacKey));
mbedtls_md_hmac_update(&ctx, plain.data() + 0x029, 0x18B); // Data
mbedtls_md_hmac_update(&ctx, cipher.data() + HMAC_POS_TAG, 0x20); // Tag HMAC
mbedtls_md_hmac_update(&ctx, plain.data() + 0x1D4, 0x34);
mbedtls_md_hmac_finish(&ctx, cipher.data() + HMAC_POS_DATA);
mbedtls_md_hmac_update(&ctx, reinterpret_cast<const unsigned char*>(&tag_data.write_counter),
input_length2); // Data
mbedtls_md_hmac_update(&ctx, reinterpret_cast<unsigned char*>(&encoded_tag_data.hmac_tag),
sizeof(HashData)); // Tag HMAC
mbedtls_md_hmac_update(&ctx, reinterpret_cast<const unsigned char*>(&tag_data.uuid),
input_length);
mbedtls_md_hmac_finish(&ctx, reinterpret_cast<unsigned char*>(&encoded_tag_data.hmac_data));
// HMAC cleanup
mbedtls_md_free(&ctx);
// Encrypt
NTAG215File encoded_tag_data{};
memcpy(&encoded_tag_data, cipher.data(), sizeof(NTAG215File));
Cipher(data_keys, tag_data, encoded_tag_data);
// Convert back to hardware

19
src/core/hle/service/nfp/amiibo_crypto.h
View File

@ -10,23 +10,23 @@
struct mbedtls_md_context_t;
namespace Service::NFP::AmiiboCrypto {
constexpr std::size_t HMAC_POS_DATA = 0x8;
constexpr std::size_t HMAC_POS_TAG = 0x1B4;
// Byte locations in Service::NFP::NTAG215File
constexpr std::size_t HMAC_DATA_START = 0x8;
constexpr std::size_t SETTINGS_START = 0x2c;
constexpr std::size_t WRITE_COUNTER_START = 0x29;
constexpr std::size_t HMAC_TAG_START = 0x1B4;
constexpr std::size_t UUID_START = 0x1D4;
constexpr std::size_t DYNAMIC_LOCK_START = 0x208;
using HmacKey = std::array<u8, 0x10>;
using DrgbOutput = std::array<u8, 0x20>;
struct HashSeed {
union {
std::array<u8, 0x40> raw;
struct {
u16 magic;
std::array<u8, 0xE> padding;
std::array<u8, 0x8> uuid1;
std::array<u8, 0x8> uuid2;
std::array<u8, 0x20> keygen_salt;
} data;
};
};
static_assert(sizeof(HashSeed) == 0x40, "HashSeed is an invalid size");
@ -71,12 +71,11 @@ u32 GetTagPassword(const TagUuid& uuid);
HashSeed GetSeed(const NTAG215File& data);
// Middle step on the generation of derived keys
void PreGenerateKey(const InternalKey& key, const HashSeed& seed, u8* output,
std::size_t& outputLen);
std::vector<u8> GenerateInternalKey(const InternalKey& key, const HashSeed& seed);
// Initializes mbedtls context
void CryptoInit(CryptoCtx& ctx, mbedtls_md_context_t& hmac_ctx, const HmacKey& hmac_key,
const u8* seed, std::size_t seed_size);
const std::vector<u8>& seed);
// Feeds data to mbedtls context to generate the derived key
void CryptoStep(CryptoCtx& ctx, mbedtls_md_context_t& hmac_ctx, DrgbOutput& output);

8
src/core/hle/service/nfp/amiibo_types.h
View File

@ -137,10 +137,10 @@ struct EncryptedAmiiboFile {
u16 write_counter; // Number of times the amiibo has been written?
INSERT_PADDING_BYTES(0x1); // Unknown 1
AmiiboSettings settings; // Encrypted amiibo settings
HashData locked_hash; // Hash
HashData hmac_tag; // Hash
AmiiboModelInfo model_info; // Encrypted amiibo model info
HashData keygen_salt; // Salt
HashData unfixed_hash; // Hash
HashData hmac_data; // Hash
Service::Mii::Ver3StoreData owner_mii; // Encrypted Mii data
u64_be title_id; // Encrypted Game id
u16_be applicaton_write_counter; // Encrypted Counter
@ -155,7 +155,7 @@ struct NTAG215File {
std::array<u8, 0x2> uuid2;
u16 static_lock; // Set defined pages as read only
u32 compability_container; // Defines available memory
HashData unfixed_hash; // Hash
HashData hmac_data; // Hash
u8 constant_value; // Must be A5
u16 write_counter; // Number of times the amiibo has been written?
INSERT_PADDING_BYTES(0x1); // Unknown 1
@ -167,7 +167,7 @@ struct NTAG215File {
std::array<u8, 0x2> unknown;
HashData hash; // Probably a SHA256-HMAC hash?
ApplicationArea application_area; // Encrypted Game data
HashData locked_hash; // Hash
HashData hmac_tag; // Hash
std::array<u8, 0x8> uuid;
AmiiboModelInfo model_info;
HashData keygen_salt; // Salt