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Extract RC4 code to separate file

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This commit is contained in:
Benedikt Reinartz 2021-05-17 07:21:44 +02:00
parent 373b7ff4c4
commit 873c6a027e
4 changed files with 79 additions and 69 deletions
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3
include/mdbtools.h
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@ -648,6 +648,9 @@ void mdb_iconv_init(MdbHandle *mdb);
void mdb_iconv_close(MdbHandle *mdb);
const char* mdb_target_charset(MdbHandle *mdb);
/* rc4.c */
void mdb_rc4(unsigned char *key, guint32 key_len, unsigned char *buf, guint32 buf_len);
/** @}*/
#ifdef __cplusplus

2
src/libmdb/Makefile.am
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@ -1,5 +1,5 @@
lib_LTLIBRARIES = libmdb.la
libmdb_la_SOURCES= catalog.c file.c table.c data.c dump.c backend.c money.c sargs.c index.c like.c write.c stats.c map.c props.c worktable.c options.c iconv.c version.c
libmdb_la_SOURCES= catalog.c file.c table.c data.c dump.c backend.c money.c sargs.c index.c like.c write.c stats.c map.c props.c worktable.c options.c iconv.c version.c rc4.c
libmdb_la_LDFLAGS = -version-info $(VERSION_INFO)
if FAKE_GLIB
libmdb_la_SOURCES += fakeglib.c

76
src/libmdb/file.c
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@ -66,69 +66,8 @@ MdbFormatConstants MdbJet3Constants = {
.tab_row_col_num_offset = 5
};
typedef struct _RC4_KEY
{
unsigned char state[256];
unsigned char x;
unsigned char y;
} RC4_KEY;
#define swap_byte(x,y) t = *(x); *(x) = *(y); *(y) = t
static ssize_t _mdb_read_pg(MdbHandle *mdb, void *pg_buf, unsigned long pg);
static void RC4_set_key(RC4_KEY *key, int key_data_len, unsigned char *key_data_ptr)
{
unsigned char t;
unsigned char index1;
unsigned char index2;
unsigned char* state;
short counter;
state = &key->state[0];
for(counter = 0; counter < 256; counter++)
state[counter] = counter;
key->x = 0;
key->y = 0;
index1 = 0;
index2 = 0;
for(counter = 0; counter < 256; counter++) {
index2 = (key_data_ptr[index1] + state[counter] + index2) % 256;
swap_byte(&state[counter], &state[index2]);
index1 = (index1 + 1) % key_data_len;
}
}
/*
* this algorithm does 'encrypt in place' instead of inbuff/outbuff
* note also: encryption and decryption use same routine
* implementation supplied by (Adam Back) at <adam at cypherspace dot org>
*/
static void RC4(RC4_KEY *key, int buffer_len, unsigned char * buff)
{
unsigned char t;
unsigned char x;
unsigned char y;
unsigned char* state;
unsigned char xorIndex;
short counter;
x = key->x;
y = key->y;
state = &key->state[0];
for(counter = 0; counter < buffer_len; counter++) {
x = (x + 1) % 256;
y = (state[x] + y) % 256;
swap_byte(&state[x], &state[y]);
xorIndex = (state[x] + state[y]) % 256;
buff[counter] ^= state[xorIndex];
}
key->x = x;
key->y = y;
}
/**
* mdb_find_file:
* @filename: path to MDB (database) file
@ -232,10 +171,13 @@ static MdbHandle *mdb_handle_from_stream(FILE *stream, MdbFileFlags flags) {
return NULL;
}
RC4_KEY rc4_key;
unsigned int tmp_key = 0x6b39dac7;
RC4_set_key(&rc4_key, 4, (unsigned char *)&tmp_key);
RC4(&rc4_key, mdb->f->jet_version == MDB_VER_JET3 ? 126 : 128, mdb->pg_buf + 0x18);
guint32 tmp_key = 0x6b39dac7;
mdb_rc4(
(unsigned char *)&tmp_key,
4,
mdb->pg_buf + 0x18,
mdb->f->jet_version == MDB_VER_JET3 ? 126 : 128
);
if (mdb->f->jet_version == MDB_VER_JET3) {
mdb->f->lang_id = mdb_get_int16(mdb->pg_buf, 0x3a);
@ -436,10 +378,8 @@ static ssize_t _mdb_read_pg(MdbHandle *mdb, void *pg_buf, unsigned long pg)
*/
if (pg != 0 && mdb->f->db_key != 0)
{
RC4_KEY rc4_key;
unsigned int tmp_key = mdb->f->db_key ^ pg;
RC4_set_key(&rc4_key, 4, (unsigned char *)&tmp_key);
RC4(&rc4_key, mdb->fmt->pg_size, pg_buf);
mdb_rc4((unsigned char*)&tmp_key, 4, pg_buf, mdb->fmt->pg_size);
}
return mdb->fmt->pg_size;

67
src/libmdb/rc4.c Normal file
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@ -0,0 +1,67 @@
#include "mdbtools.h"
typedef struct _RC4_KEY
{
unsigned char state[256];
unsigned char x;
unsigned char y;
} RC4_KEY;
#define swap_byte(x,y) t = *(x); *(x) = *(y); *(y) = t
static void RC4_set_key(RC4_KEY *key, int key_data_len, unsigned char *key_data_ptr)
{
unsigned char t;
unsigned char index1;
unsigned char index2;
unsigned char* state;
short counter;
state = &key->state[0];
for(counter = 0; counter < 256; counter++)
state[counter] = counter;
key->x = 0;
key->y = 0;
index1 = 0;
index2 = 0;
for(counter = 0; counter < 256; counter++) {
index2 = (key_data_ptr[index1] + state[counter] + index2) % 256;
swap_byte(&state[counter], &state[index2]);
index1 = (index1 + 1) % key_data_len;
}
}
/*
* this algorithm does 'encrypt in place' instead of inbuff/outbuff
* note also: encryption and decryption use same routine
* implementation supplied by (Adam Back) at <adam at cypherspace dot org>
*/
static void RC4(RC4_KEY *key, int buffer_len, unsigned char * buff)
{
unsigned char t;
unsigned char x;
unsigned char y;
unsigned char* state;
unsigned char xorIndex;
short counter;
x = key->x;
y = key->y;
state = &key->state[0];
for(counter = 0; counter < buffer_len; counter++) {
x = (x + 1) % 256;
y = (state[x] + y) % 256;
swap_byte(&state[x], &state[y]);
xorIndex = (state[x] + state[y]) % 256;
buff[counter] ^= state[xorIndex];
}
key->x = x;
key->y = y;
}
void mdb_rc4(unsigned char *key, guint32 key_len, unsigned char *buf, guint32 buf_len) {
RC4_KEY rc4_key;
RC4_set_key(&rc4_key, key_len, key);
RC4(&rc4_key, buf_len, buf);
}