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)

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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().