libavformat/asfcrypt.c File Reference

#include "libavutil/common.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/bswap.h"
#include "libavutil/des.h"
#include "libavutil/rc4.h"
#include "asfcrypt.h"

Go to the source code of this file.

Functions

static uint32_t inverse (uint32_t v)
 find multiplicative inverse modulo 2 ^ 32
static void multiswap_init (const uint8_t keybuf[48], uint32_t keys[12])
 read keys from keybuf into keys
static void multiswap_invert_keys (uint32_t keys[12])
 invert the keys so that encryption become decryption keys and the other way round.
static uint32_t multiswap_step (const uint32_t keys[12], uint32_t v)
static uint32_t multiswap_inv_step (const uint32_t keys[12], uint32_t v)
static uint64_t multiswap_enc (const uint32_t keys[12], uint64_t key, uint64_t data)
 "MultiSwap" encryption
static uint64_t multiswap_dec (const uint32_t keys[12], uint64_t key, uint64_t data)
 "MultiSwap" decryption
void ff_asfcrypt_dec (const uint8_t key[20], uint8_t *data, int len)


Function Documentation

void ff_asfcrypt_dec ( const uint8_t  key[20],
uint8_t data,
int  len 
)

Definition at line 138 of file asfcrypt.c.

Referenced by ff_asf_parse_packet().

static uint32_t inverse ( uint32_t  v  )  [static]

find multiplicative inverse modulo 2 ^ 32

Parameters:
v number to invert, must be odd!
Returns:
number so that result * v = 1 (mod 2^32)

Definition at line 35 of file asfcrypt.c.

Referenced by multiswap_invert_keys().

static uint64_t multiswap_dec ( const uint32_t  keys[12],
uint64_t  key,
uint64_t  data 
) [static]

"MultiSwap" decryption

Parameters:
keys 32 bit numbers in machine endianness, 0-4 and 6-10 must be inverted from encryption
key another key, this one must be the same as for the encryption
data data to decrypt
Returns:
decrypted data

Definition at line 124 of file asfcrypt.c.

Referenced by ff_asfcrypt_dec().

static uint64_t multiswap_enc ( const uint32_t  keys[12],
uint64_t  key,
uint64_t  data 
) [static]

"MultiSwap" encryption

Parameters:
keys 32 bit numbers in machine endianness, 0-4 and 6-10 must be inverted from decryption
key another key, this one must be the same for the decryption
data data to encrypt
Returns:
encrypted data

Definition at line 102 of file asfcrypt.c.

Referenced by ff_asfcrypt_dec().

static void multiswap_init ( const uint8_t  keybuf[48],
uint32_t  keys[12] 
) [static]

read keys from keybuf into keys

Parameters:
keybuf buffer containing the keys
keys output key array containing the keys for encryption in native endianness

Definition at line 53 of file asfcrypt.c.

Referenced by ff_asfcrypt_dec().

static uint32_t multiswap_inv_step ( const uint32_t  keys[12],
uint32_t  v 
) [static]

Definition at line 83 of file asfcrypt.c.

Referenced by multiswap_dec().

static void multiswap_invert_keys ( uint32_t  keys[12]  )  [static]

invert the keys so that encryption become decryption keys and the other way round.

Parameters:
keys key array of ints to invert

Definition at line 64 of file asfcrypt.c.

Referenced by ff_asfcrypt_dec().

static uint32_t multiswap_step ( const uint32_t  keys[12],
uint32_t  v 
) [static]

Definition at line 72 of file asfcrypt.c.

Referenced by multiswap_enc().


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