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Code Issues Releases Activity

Fix minor build issues in gcm.c, etc.

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This commit is contained in:
TuxSH 2018-02-20 19:29:44 +01:00
parent 25e6317272
commit 81b874cc14
2 changed files with 36 additions and 43 deletions
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75
exosphere/gcm.c
View file

@ -7,14 +7,14 @@
#include "se.h"
/* Shifts right a little endian 128-bit value. */
void shr_128(uint64_t *val) {
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. */
void shl_128(uint64_t *val) {
static void shl_128(uint64_t *val) {
val[1] <<= 1;
val[1] |= (val[0] & (1ULL << 63)) >> 63;
val[0] <<= 1;
@ -22,11 +22,11 @@ void shl_128(uint64_t *val) {
/* Multiplies two 128-bit numbers X,Y in the GF(128) Galois Field. */
void gf128_mul(uint8_t *dst, const uint8_t *x, const uint8_t *y) {
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]);
@ -37,17 +37,17 @@ void gf128_mul(uint8_t *dst, const uint8_t *x, const uint8_t *y) {
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 xor = 0xE1 * (x_work[0] & 1);
uint8_t xval = 0xE1 * (x_work[0] & 1);
shr_128(p_x);
x_work[0xF] ^= xor;
x_work[0xF] ^= xval;
}
for (unsigned int i = 0; i < 0x10; i++) {
dst[i] = dst_work[0xF-i];
}
@ -56,50 +56,48 @@ void gf128_mul(uint8_t *dst, const uint8_t *x, const uint8_t *y) {
/* Performs an AES-GCM GHASH operation over the data into dst. */
void ghash(void *dst, const void *data, size_t data_size, const void *j_block, int encrypt) {
static void ghash(void *dst, const void *data, size_t data_size, const void *j_block, int encrypt) {
uint8_t x[0x10];
uint8_t h[0x10];
uint64_t *p_x = (uint64_t *)(&x[0]);
uint64_t *p_data = (uint64_t *)data;
for (unsigned int i = 0; i < 0x10; i++) {
x[i] = 0;
}
memset(x, 0, 0x10);
/* H = aes_ecb_encrypt(zeroes) */
se_aes_ecb_encrypt_block(KEYSLOT_SWITCH_TEMPKEY, h, 0x10, x, 0x10);
size_t total_size = data_size;
while (data_size >= 0x10) {
/* X = (X ^ current_block) * H */
p_x[0] ^= p_data[0];
p_x[1] ^= p_data[1];
gf128_mul(x, x, h)
gf128_mul(x, x, h);
/* Increment p_data by 0x10 bytes. */
p_data += 2;
data_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 (data_size & 0xF) {
gf128_mul(x, x, h)
gf128_mul(x, x, h);
}
/* Due to a Nintendo bug, the wrong QWORD gets XOR'd in the "final output block" case. */
if (encrypt) {
p_x[1] ^= (uint64_t)(total_size << 3);
} else {
p_x[0] ^= (uint64_t)(total_size << 3);
}
gf128_mul(x, x, h)
gf128_mul(x, x, h);
/* If final output block, XOR with encrypted J block. */
if (encrypt) {
se_aes_ecb_encrypt_block(KEYSLOT_SWITCH_TEMPKEY, h, 0x10, j_block, 0x10);
@ -107,19 +105,14 @@ void ghash(void *dst, const void *data, size_t data_size, const void *j_block, i
x[i] ^= h[i];
}
}
/* Copy output. */
for (unsigned int i = 0; i < 0x10; i++) {
((uint8_t *)dst)[i] = x[i];
}
memcpy(dst, x, 0x10);
}
/* This function is a doozy. It decrypts and validates a (non-standard) AES-GCM wrapped keypair. */
int gcm_decrypt_key(unsigned int keyslot, void *dst, size_t dst_size, const void *src, size_t src_size, const void *sealed_kek, size_t kek_size, const void *wrapped_key, size_t key_size, unsigned int usecase, int is_personalized) {
size_t gcm_decrypt_key(unsigned int keyslot, void *dst, size_t dst_size, const void *src, size_t src_size, const void *sealed_kek, size_t kek_size, const void *wrapped_key, size_t key_size, unsigned int usecase, int is_personalized) {
if (is_personalized == 0) {
/* Devkit keys use a different keyformat without a MAC/Device ID. */
if (src_size <= 0x10 || src_size - 0x10 > dst_size) {
@ -130,30 +123,30 @@ int gcm_decrypt_key(unsigned int keyslot, void *dst, size_t dst_size, const void
panic();
}
}
/* Unwrap the key */
unseal_key(KEYSLOT_SWITCH_TEMPKEY, sealed_kek, kek_size, usecase);
decrypt_data_into_keyslot(KEYSLOT_SWITCH_TEMPKEY, KEYSLOT_SWITCH_TEMPKEY, wrapped_key, key_size);
/* Decrypt the GCM keypair, AES-CTR with CTR = blob[:0x10]. */
se_aes_ctr_crypt(KEYSLOT_SWITCH_TEMPKEY, dst, dst_size, src + 0x10, src_size - 0x10, src, 0x10);
if (is_personalized == 0) {
/* Devkit non-personalized keys have no further authentication. */
return src_size - 0x10;
}
/* J = GHASH(CTR); */
uint8_t j_block[0x10];
ghash(j_block, src, 0x10, NULL, 0);
/* MAC = GHASH(PLAINTEXT) ^ ENCRYPT(J) */
/* Note: That MAC is calculated over plaintext is non-standard. */
/* It is supposed to be over the ciphertext. */
uint8_t calc_mac[0x10];
ghash(calc_mac, dst, src_size - 0x20, j_block, 1);
/* Const-time memcmp. */
int different = 0;
for (unsigned int i = 0; i < 0x10; i++) {
@ -162,8 +155,8 @@ int gcm_decrypt_key(unsigned int keyslot, void *dst, size_t dst_size, const void
if (different) {
return 0;
}
/* TODO: Validate Device ID matches in blob data from fuses. */
return src_size - 0x30;
}
}

4
exosphere/gcm.h
View file

@ -3,6 +3,6 @@
#include <stdint.h>
int gcm_decrypt_key(unsigned int keyslot, void *dst, size_t dst_size, const void *src, size_t src_size, const void *sealed_kek, size_t kek_size, const void *wrapped_key, size_t key_size, unsigned int usecase, int is_personalized);
size_t gcm_decrypt_key(unsigned int keyslot, void *dst, size_t dst_size, const void *src, size_t src_size, const void *sealed_kek, size_t kek_size, const void *wrapped_key, size_t key_size, unsigned int usecase, int is_personalized);
#endif
#endif