1
0
Fork 0
mirror of https://github.com/s1204IT/Lockpick_RCM.git synced 2024-11-09 20:11:49 +00:00
Lockpick_RCM/source/keys/gmac.c
2022-10-31 21:46:38 -07:00

130 lines
3.8 KiB
C

/*
* Copyright (c) 2018-2020 Atmosphère-NX
* Copyright (c) 2019-2022 shchmue
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "gmac.h"
#include <sec/se.h>
#include <sec/se_t210.h>
#include <stdint.h>
#include <string.h>
/* Shifts right a little endian 128-bit value. */
static void _shr_128(uint64_t *val) {
val[0] >>= 1;
val[0] |= (val[1] & 1) << 63;
val[1] >>= 1;
}
/* Shifts left a little endian 128-bit value. */
static void _shl_128(uint64_t *val) {
val[1] <<= 1;
val[1] |= (val[0] & (1ull << 63)) >> 63;
val[0] <<= 1;
}
/* Multiplies two 128-bit numbers X,Y in the GF(128) Galois Field. */
static void _gf128_mul(uint8_t *dst, const uint8_t *x, const uint8_t *y) {
uint8_t x_work[0x10];
uint8_t y_work[0x10];
uint8_t dst_work[0x10];
uint64_t *p_x = (uint64_t *)(&x_work[0]);
uint64_t *p_y = (uint64_t *)(&y_work[0]);
uint64_t *p_dst = (uint64_t *)(&dst_work[0]);
/* Initialize buffers. */
for (unsigned int i = 0; i < 0x10; i++) {
x_work[i] = x[0xF-i];
y_work[i] = y[0xF-i];
dst_work[i] = 0;
}
/* Perform operation for each bit in y. */
for (unsigned int round = 0; round < 0x80; round++) {
p_dst[0] ^= p_x[0] * ((y_work[0xF] & 0x80) >> 7);
p_dst[1] ^= p_x[1] * ((y_work[0xF] & 0x80) >> 7);
_shl_128(p_y);
uint8_t xval = 0xE1 * (x_work[0] & 1);
_shr_128(p_x);
x_work[0xF] ^= xval;
}
for (unsigned int i = 0; i < 0x10; i++) {
dst[i] = dst_work[0xF-i];
}
}
static void _ghash(u32 ks, void *dst, const void *src, u32 src_size, const void *j_block, bool encrypt) {
uint8_t x[0x10] = {0};
uint8_t h[0x10];
uint64_t *p_x = (uint64_t *)(&x[0]);
uint64_t *p_data = (uint64_t *)src;
/* H = aes_ecb_encrypt(zeroes) */
se_aes_crypt_block_ecb(ks, ENCRYPT, h, x);
u64 total_size = src_size;
while (src_size >= 0x10) {
/* X = (X ^ current_block) * H */
p_x[0] ^= p_data[0];
p_x[1] ^= p_data[1];
_gf128_mul(x, x, h);
/* Increment p_data by 0x10 bytes. */
p_data += 2;
src_size -= 0x10;
}
/* Nintendo's code *discards all data in the last block* if unaligned. */
/* And treats that block as though it were all-zero. */
/* This is a bug, they just forget to XOR with the copy of the last block they save. */
if (src_size & 0xF) {
_gf128_mul(x, x, h);
}
uint64_t xor_size = total_size << 3;
xor_size = __builtin_bswap64(xor_size);
/* Due to a Nintendo bug, the wrong QWORD gets XOR'd in the "final output block" case. */
if (encrypt) {
p_x[0] ^= xor_size;
} else {
p_x[1] ^= xor_size;
}
_gf128_mul(x, x, h);
/* If final output block, XOR with encrypted J block. */
if (encrypt) {
se_aes_crypt_block_ecb(ks, ENCRYPT, h, j_block);
for (unsigned int i = 0; i < 0x10; i++) {
x[i] ^= h[i];
}
}
/* Copy output. */
memcpy(dst, x, 0x10);
}
void calc_gmac(u32 ks, void *out_gmac, const void *data, u32 size, const void *key, const void *iv) {
u32 j_block[4] = {0};
se_aes_key_set(ks, key, 0x10);
_ghash(ks, j_block, iv, 0x10, NULL, false);
_ghash(ks, out_gmac, data, size, j_block, true);
}