FFmpeg: libavformat/asfcrypt.c File Reference

FFmpeg

libavformat

asfcrypt.c File Reference

#include <stddef.h>
#include "libavutil/bswap.h"
#include "libavutil/des.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/mem.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 More...

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

read keys from keybuf into keys More...

static void multiswap_invert_keys (uint32_t keys[12])

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

static uint32_t multiswap_step (const uint32_t keys[6], uint32_t v)

static uint32_t multiswap_inv_step (const uint32_t keys[6], uint32_t v)

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

"MultiSwap" encryption More...

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

"MultiSwap" decryption More...

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

Function Documentation

◆ inverse()

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 36 of file asfcrypt.c.

Referenced by multiswap_invert_keys().

◆ multiswap_init()

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 55 of file asfcrypt.c.

Referenced by ff_asfcrypt_dec().

◆ multiswap_invert_keys()

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 67 of file asfcrypt.c.

Referenced by ff_asfcrypt_dec().

◆ multiswap_step()

static uint32_t multiswap_step ( const uint32_t keys[6],

uint32_t v

)

static

Definition at line 76 of file asfcrypt.c.

Referenced by multiswap_enc().

◆ multiswap_inv_step()

static uint32_t multiswap_inv_step ( const uint32_t keys[6],

uint32_t v

)

static

Definition at line 88 of file asfcrypt.c.

Referenced by multiswap_dec().

◆ multiswap_enc()

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 108 of file asfcrypt.c.

Referenced by ff_asfcrypt_dec().

◆ multiswap_dec()

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 132 of file asfcrypt.c.

Referenced by ff_asfcrypt_dec().

◆ ff_asfcrypt_dec()

void ff_asfcrypt_dec ( const uint8_t key[20],

uint8_t * data,

int len

)

Definition at line 148 of file asfcrypt.c.

Referenced by asf_parse_packet(), asf_read_multiple_payload(), and asf_read_single_payload().

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