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Reinstated even/odd AES keys

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spdfrk1 2014-07-10 18:24:40 +02:00 • committed by Jaroslav Kysela
parent 66f6a3b99b
commit a558c9e228
1 changed files with 12 additions and 13 deletions
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25
src/descrambler/libaesdec/libaesdec.c
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@ -16,34 +16,28 @@
struct aes_keys_t {
AES_KEY even;
AES_KEY odd; // Reserved for future use
AES_KEY odd;
};
unsigned char * keybuffer;
// Even and Odd cw represent one full 128-bit AES key
void aes_set_even_control_word(void *keys, const unsigned char *pk) {
memcpy(keybuffer, pk, 8);
AES_set_decrypt_key(keybuffer, 128, &((struct aes_keys_t *) keys)->even);
AES_set_decrypt_key(pk, 128, &((struct aes_keys_t *) keys)->even);
}
void aes_set_odd_control_word(void *keys, const unsigned char *pk) {
memcpy(keybuffer + 8, pk, 8);
AES_set_decrypt_key(keybuffer, 128, &((struct aes_keys_t *) keys)->even);
AES_set_decrypt_key(pk, 128, &((struct aes_keys_t *) keys)->odd);
}
//-----set control words
void aes_set_control_words(void *keys, const unsigned char *ev,
const unsigned char *od) {
memcpy(keybuffer, ev, 8);
memcpy(keybuffer + 8, od, 8);
AES_set_decrypt_key(keybuffer, 128, &((struct aes_keys_t *) keys)->even);
AES_set_decrypt_key(ev, 128, &((struct aes_keys_t *) keys)->even);
AES_set_decrypt_key(od, 128, &((struct aes_keys_t *) keys)->odd);
}
//-----key structure
void *aes_get_key_struct(void) {
keybuffer = calloc(16, 1);
struct aes_keys_t *keys = (struct aes_keys_t *) malloc(
sizeof(struct aes_keys_t));
if (keys) {
@ -54,7 +48,6 @@ void *aes_get_key_struct(void) {
}
void aes_free_key_struct(void *keys) {
free(keybuffer);
return free(keys);
}
@ -62,6 +55,7 @@ void aes_free_key_struct(void *keys) {
void aes_decrypt_packet(void *keys, unsigned char *packet) {
unsigned char *pkt;
unsigned char ev_od = 0;
int xc0, len, offset, n;
pkt = packet;
@ -78,6 +72,7 @@ void aes_decrypt_packet(void *keys, unsigned char *packet) {
}
if (xc0 == 0x80 || xc0 == 0xc0) { // encrypted
ev_od = (xc0 & 0x40) >> 6; // 0 even, 1 odd
pkt[3] &= 0x3f; // consider it decrypted now
if (pkt[3] & 0x20) { // incomplete packet
offset = 4 + pkt[4] + 1;
@ -95,7 +90,11 @@ void aes_decrypt_packet(void *keys, unsigned char *packet) {
return;
}
k = ((struct aes_keys_t *) keys)->even;
if (ev_od == 0) {
k = ((struct aes_keys_t *) keys)->even;
} else {
k = ((struct aes_keys_t *) keys)->odd;
}
// TODO room for improvement?
int i;