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Introduce ctr_decrypt_boffset() function

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This commit is contained in:
d0k3 2016-11-21 22:50:47 +01:00
parent b70761e6aa
commit 4bd787ace9
3 changed files with 50 additions and 42 deletions
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42
source/nand/aes.c
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@ -85,7 +85,7 @@ void add_ctr(void* ctr, uint32_t carry)
uint32_t sum;
int32_t i;
for(i = 0; i < 4; i++) {
for(i=0; i < 4; i++) {
counter[i] = ((uint32_t)outctr[i*4+0]<<24) | ((uint32_t)outctr[i*4+1]<<16) | ((uint32_t)outctr[i*4+2]<<8) | ((uint32_t)outctr[i*4+3]<<0);
}
@ -110,6 +110,46 @@ void add_ctr(void* ctr, uint32_t carry)
}
}
void ctr_decrypt_boffset(void *inbuf, void *outbuf, size_t size, size_t off, uint32_t mode, uint8_t *ctr)
{
size_t bytes_left = size;
size_t off_fix = off % AES_BLOCK_SIZE;
uint8_t temp[AES_BLOCK_SIZE];
uint8_t ctr_local[16];
uint8_t *in = inbuf;
uint8_t *out = outbuf;
uint32_t i;
for (i=0; i<16; i++) // setup local ctr
ctr_local[i] = ctr[i];
add_ctr(ctr_local, off / AES_BLOCK_SIZE);
if (off_fix) // handle misaligned offset (at beginning)
{
for (i=off_fix; i<AES_BLOCK_SIZE; i++)
temp[i] = *(in++);
ctr_decrypt(temp, temp, 1, mode, ctr_local);
for (i=off_fix; i<AES_BLOCK_SIZE; i++)
*(out++) = temp[i];
bytes_left -= AES_BLOCK_SIZE - off_fix;
}
ctr_decrypt(in, out, bytes_left / AES_BLOCK_SIZE, mode, ctr_local);
in += AES_BLOCK_SIZE * (uint32_t) (bytes_left / AES_BLOCK_SIZE);
out += AES_BLOCK_SIZE * (uint32_t) (bytes_left / AES_BLOCK_SIZE);
bytes_left -= AES_BLOCK_SIZE * (uint32_t) (bytes_left / AES_BLOCK_SIZE);
if (bytes_left) // handle misaligned offset (at end)
{
for (i=0; i<bytes_left; i++)
temp[i] = *(in++);
ctr_decrypt(temp, temp, 1, mode, ctr_local);
for (i=0; i<bytes_left; i++)
*(out++) = temp[i];
bytes_left = 0;
}
}
void ctr_decrypt(void *inbuf, void *outbuf, size_t size, uint32_t mode, uint8_t *ctr)
{
size_t blocks_left = size;

1
source/nand/aes.h
View File

@ -54,6 +54,7 @@ void set_ctr(void* iv);
void add_ctr(void* ctr, uint32_t carry);
void aes_decrypt(void* inbuf, void* outbuf, size_t size, uint32_t mode);
void ctr_decrypt(void* inbuf, void* outbuf, size_t size, uint32_t mode, uint8_t *ctr);
void ctr_decrypt_boffset(void *inbuf, void *outbuf, size_t size, size_t off, uint32_t mode, uint8_t *ctr);
void aes_cmac(void* inbuf, void* outbuf, size_t size);
void aes_fifos(void* inbuf, void* outbuf, size_t blocks);
void set_aeswrfifo(uint32_t value);

49
source/virtual/sddata.c
View File

@ -52,44 +52,6 @@ FilCryptInfo* fx_find_cryptinfo(FIL* fptr) {
return info;
}
void fx_crypt(FilCryptInfo* info, void* buff, FSIZE_t off, UINT bt) {
u32 mode = AES_CNT_CTRNAND_MODE;
u8 ctr[16] __attribute__((aligned(32)));
u8 buff16[16];
u8* buffer = buff;
// copy CTR and increment it
memcpy(ctr, info->ctr, 16);
add_ctr(ctr, off / 16);
// setup the key
setup_aeskeyY(0x34, info->keyy);
use_aeskey(0x34);
// handle misaligned offset (at beginning)
if (off % 16) {
memcpy(buff16 + (off % 16), buffer, 16 - (off % 16));
ctr_decrypt(buff16, buff16, 1, mode, ctr);
memcpy(buffer, buff16 + (off % 16), 16 - (off % 16));
buffer += 16 - (off % 16);
bt -= 16 - (off % 16);
}
// de/encrypt the data
ctr_decrypt(buffer, buffer, bt / 16, mode, ctr);
buffer += 16 * (UINT) (bt / 16);
bt -= 16 * (UINT) (bt / 16);
// handle misaligned offset (at end)
if (bt) {
memcpy(buff16, buffer, bt);
ctr_decrypt(buff16, buff16, 1, mode, ctr);
memcpy(buffer, buff16, bt);
buffer += bt;
bt = 0;
}
}
FRESULT fx_open (FIL* fp, const TCHAR* path, BYTE mode) {
int num = alias_num(path);
FilCryptInfo* info = fx_find_cryptinfo(fp);
@ -122,8 +84,11 @@ FRESULT fx_read (FIL* fp, void* buff, UINT btr, UINT* br) {
FilCryptInfo* info = fx_find_cryptinfo(fp);
FSIZE_t off = f_tell(fp);
FRESULT res = f_read(fp, buff, btr, br);
if (info && info->fptr)
fx_crypt(info, buff, off, btr);
if (info && info->fptr) {
setup_aeskeyY(0x34, info->keyy);
use_aeskey(0x34);
ctr_decrypt_boffset(buff, buff, btr, off, AES_CNT_CTRNAND_MODE, info->ctr);
}
return res;
}
@ -132,12 +97,14 @@ FRESULT fx_write (FIL* fp, const void* buff, UINT btw, UINT* bw) {
FSIZE_t off = f_tell(fp);
FRESULT res = FR_OK;
if (info && info->fptr) {
setup_aeskeyY(0x34, info->keyy);
use_aeskey(0x34);
*bw = 0;
for (UINT p = 0; (p < btw) && (res == FR_OK); p += SDCRYPT_BUFFER_SIZE) {
UINT pcount = min(SDCRYPT_BUFFER_SIZE, (btw - p));
UINT bwl = 0;
memcpy(SDCRYPT_BUFFER, (u8*) buff + p, pcount);
fx_crypt(info, SDCRYPT_BUFFER, off + p, pcount);
ctr_decrypt_boffset(SDCRYPT_BUFFER, SDCRYPT_BUFFER, pcount, off + p, AES_CNT_CTRNAND_MODE, info->ctr);
res = f_write(fp, (const void*) SDCRYPT_BUFFER, pcount, &bwl);
*bw += bwl;
}